# Will reverse polarity trip breaker??



## Duane 70 (Sep 16, 2008)

Our kids just bought us a new LCD HD TV. We plugged it into the same switched receptacle used by the old TV for 6 yrs. with no problems. Started to connect the TV cable and got shocked - thought what the f---!!! Unplugged it and hooked up the cable. Plugged it in, turned it on and the breaker (15 amp) tripped after about 4-5 seconds. Took TV back to store and got another one (same model). Tried hooking up again - no shock this time but still tripped breaker. Took TV back to store and went to another store and bought a different brand/model. Hooked up, turned on, still tripped breaker - what the f---??? Brother-in-Law said sounds like the polarity may be reversed. Get multimeter and check other outlets for correct polarity. Other circuts tested correct. Run extension cord from correctly wired outlet to TV, turned on, works good. So I reversed the wiring on the TV receptacle, disconnected the switch and tried the TV again - works good. Tested the other outlets on the same circut and they all test correct polarity. What is going on? Did builder/electrician somehow get the wiring reversed somewhere on the switched outlet? All wires I can see seem to be connected correctly. Do the new TVs require correct polarity to work? Why would the breaker trip? Wouldn't the TV have to be pulling more than 15 amps? Would reverse polarity cause that - somehow a dead short??? Thanks for any suggestions/ideas.


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## J. V. (Jun 1, 2007)

How did you check polarity with a multimeter and 120 volt ac circuit. You can determine the hot from the neutral though. Is the white (neutral) on the silver colored screws on the receptacle? Check the white to ground and the hot to ground to check correct connection of the receptacle. You say the recept is switched? If so the switch leg wire may be white. Do not use the switched side of the recept for the TV. Use the continous hot (usually the top).
Can you plug something else into this recept. and see if it is working correctly? Since the old set worked fine on this recept, it is something of a mistery to me. I am not sure that polarity is the issue, but it could be. What is the current rating of the TV? Is this a big screen TV?


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## Ultrarunner2017 (Oct 1, 2008)

It wouldn't just happen that the 15A breaker your TV is connected to is a GFCI, is it?
If so, the TV will trip the breaker when the polarity is wrong, because there is leakage through capacitance to ground. It is a normal thing for TV to have this.
That said, if the breaker is not GFCI, there is a problem. I cannot imagine for an instant that UL would approve any appliance that would, when plugged into an improperly wired receptacle allow the user to get a shock for any reason.
Connecting the cable or antenna to a TV should never give someone a shock!
That said, did you experience a "full" 115V shock, or was it less than that?
Also, was there a big spark when you touched the CATV line to the TV?
If there were enough current to trip a 15A breaker (even after a few minutes), you would see a large spark.

When I lived in my apartment, I was getting a small amount of current through me when I was hooking up the cable TV to the television. This happened because the STB (set top box) had surge suppressors in it, and there was a small amount of current (far from what would have hurt me) flowing through the CATV shield to ground.
This would most likely have tripped a GFCI, but none was installed.

If I were you, I would disconnect the CATV/Sat line from the TV, and measure the potential between it and the ground (not neutral) of a known-good receptacle.
There should never be 110V there. You may get a reading of between 25V and 40V, but that's as much as I would ever tolerate being on that line.


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## Yoyizit (Jul 11, 2008)

Duane 70 said:


> the breaker (15 amp)
> tripped after about 4-5 seconds.
> *So ~45A flowed. *
> *Probably your coax cable shield and cable insulation is damaged.*


I assume the TVs have ground pins in their plugs.


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## rgsgww (Jul 5, 2008)

How old is the wiring in this house?

Can you post pics of the culprit outlet?


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## Duane 70 (Sep 16, 2008)

Thanks for the replies. First, the outlet/circut is not on GFCI. The wires were connected originally black wire to gold screw/white wire to silver screw. I know everything is connected correctly in the breaker panel because we just an electrician put in a new panel and breakers last year to replace an old Zinsco setup. I watched everything he did and all blacks (120v lines) are connected to the breakers and all whites to the neutral bar w/all grounds to the ground bar. Yes, on the first set, there was a good shock and spark - like 120v type. I switched the wire on the outlet to white on gold and black on silver and the TV works OK. I actualy replaced the receptacle with a new one and removed the wire from the switch so the outlet is no longer switched, just straight wired with the rest of the circut. Strangely, the rest of the outlets on this circut are wired correctly. I tested this with a multimeter set on 200 volts and tested between hot an neutral (118 v), between hot and ground (118 v) and between neutral and ground (0 v) on the all the outlets. The house is 30 years old and all circuts except one show ground connected. The outlet that was switched for the TV did not show a ground even though it has a ground wire connected to it. Not sure where it goes but it seems if the rest of the outlets on this circut have ground then the switched outlet should also have had ground but appeared not to. I guess my terminology is wrong. When I say I checked the polarity, I mean I checked the correct positioning of the hot and neutral wires. Does anyone know if that would cause a TV (40" LCD HD) to not work or trip the breaker if the wiring is reversed? Sounds odd to me. Haven't encountered any problems since I switched the wires around. Any more ideas on this???


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## jbfan (Jul 1, 2004)

If you have the black wire on the silver screw, then you have the receptacle wired incorrectly.
You need to trace this circuit out and find where the mix up is located and fix it.


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## Ultrarunner2017 (Oct 1, 2008)

jbfan said:


> If you have the black wire on the silver screw, then you have the receptacle wired incorrectly.
> You need to trace this circuit out and find where the mix up is located and fix it.


Exactly! One of the upstream receptacles has it's downstream wiring connected incorrectly.
Perhaps at the now removed switch?


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## Duane 70 (Sep 16, 2008)

That's what I don't understand. The rest of the outlets on this circut are wired correctly, black to gold, white to silver. The switched outlet was also black to gold and white to silver when it was tripping the breaker. Had to change that outlet to black to silver and white to gold to get the TV to work. I'm thinking it has to be with the switch somewhere - except the switch is now disconnected and the TV still works with black to silver and white to gold. Also, why would the breaker trip with reversed wiring? Wouldn't it have to be pulling more than 15 amps? What would cause this with just the wiring reversed and why would the original TV work without any problems for 6 years??


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## Duane 70 (Sep 16, 2008)

I guess my main question is why the outlet/circuit worked fine with my old TV (37" tube set) for so many years, but tripped the breaker with the new LCD 40" set? The only difference that I can see is that the old set did not have a ground wire in the cord, where the new set has a ground wire/plug prong in the cord. Are the new TVs electronics so sensitive that reversed wiring in an outlet would trip a 15 amp breaker? I'm not so sure that reversed wiring is the problem. The wires were correct when I pulled the outlet (black to gold, white to silver) as well as all of the other outlets on the some circuit. After reversing the wires on the TV outlet, the TV works OK. I'm wondering if by removing the wire the on the outlet from the switch, making the outlet non-switched, was actually the thing that corrected the problem? If it was a switch to outlet wiring problem, wouldn't that already have caused the breaker to trip with the old TV?? I haven't tried putting the wires on the outlet back in their correct locations because I hate to take a chance on screwing something up in the TV if it trips the breaker again by doing that since it works OK now as is. Just can't figure out why reversed wiring would cause the breaker to trip. Any takers on this puzzle??


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## rgsgww (Jul 5, 2008)

Duane 70 said:


> I guess my main question is why the outlet/circuit worked fine with my old TV (37" tube set) for so many years, but tripped the breaker with the new LCD 40" set? The only difference that I can see is that the old set did not have a ground wire in the cord, where the new set has a ground wire/plug prong in the cord. Are the new TVs electronics so sensitive that reversed wiring in an outlet would trip a 15 amp breaker? I'm not so sure that reversed wiring is the problem. The wires were correct when I pulled the outlet (black to gold, white to silver) as well as all of the other outlets on the some circuit. After reversing the wires on the TV outlet, the TV works OK. I'm wondering if by removing the wire the on the outlet from the switch, making the outlet non-switched, was actually the thing that corrected the problem? If it was a switch to outlet wiring problem, wouldn't that already have caused the breaker to trip with the old TV?? I haven't tried putting the wires on the outlet back in their correct locations because I hate to take a chance on screwing something up in the TV if it trips the breaker again by doing that since it works OK now as is. Just can't figure out why reversed wiring would cause the breaker to trip. Any takers on this puzzle??


Hmmm...Something isn't wired right. I wouldn't leave it like it is because this is a hazard.

Check any junctions. Find the cable going to that outlet, disconnect it, test resistance between ground and neutral, hot and neutral and hot and ground.


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## Stubbie (Jan 7, 2007)

Duane

Please check the tv coax ground shield for voltage...you got shocked to the tune of 120 volts you said. This didn't magically go away by reversing the wires on the receptacle. When you unplugged the new tv with grounded cord you were able to connect the tv coax to the tv. Then when you plugged it back in it tripped the breaker.


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## rgsgww (Jul 5, 2008)

Check the coaxial shield...forgot about that. Im thinking the voltage may be present on the coax.


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## Duane 70 (Sep 16, 2008)

Obviously I am not an electrician, nor I play one on the internet, but why wouldn't the problem expose itself with the old TV that was plugged into that same outlet and the same cable for 6 years (we just bought the house six years ago) and have had other things (vac. sweeper, Christmas tree lights, etc) plugged into it with no problems. Could it possibly be that a ground was connected incorrectly somehow, somewhere with that switched outlet setup since the other previous things plugged into it didn't have a ground wire in the cord plug?? Just seems totally strange occurrance to me.


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## rgsgww (Jul 5, 2008)

Duane 70 said:


> Obviously I am not an electrician, nor I play one on the internet, but why wouldn't the problem expose itself with the old TV that was plugged into that same outlet and the same cable for 6 years (we just bought the house six years ago) and have had other things (vac. sweeper, Christmas tree lights, etc) plugged into it with no problems. Could it possibly be that a ground was connected incorrectly somehow, somewhere with that switched outlet setup since the other previous things plugged into it didn't have a ground wire in the cord plug?? Just seems totally strange occurrance to me.



Seems like a ground may be installed incorrectly. Eliminate all junction points until you find the problem.


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## theatretch85 (May 17, 2008)

Sounds to me like current leakage to the coax sheild somewhere along the line, and now the new TV is more sensitive to this and is causing the breaker to trip. I would say as a TEST, wire the outlet back to normal (black to brass [to save your a**] and white to silver) use a 2 prong to 3 prong converter and plug the tv in with that. It effectively "lifts" the ground on the tv; your old tv didn't have a ground in the cord. I suspect that if it works this way, you have an issue with the coax cable. Could be as simple as a bad or no ground at the grounding block on the outside of your house. 

To check for a difference in potential between the Coax ground and your electrical ground, use a known good grounded extension cord to a know good grounded outlet (check the outlet ground with a meter) then reference the coax ground to the outlet ground and see what you get. If you get a high reading, go track down that ground block outside your house and see if its got a good ground wire attached to it.


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## Duane 70 (Sep 16, 2008)

A bad, insufficent or improperly wired ground is what I am thinking also, just didn't think about it maybe being in the TV cable. I will try the 3-2 prong adapter test on the TV. Actually I had thought about doing that the other day but already had the heavy as..ed TV cabinet pushed back in place. I will check the cable ground, or maybe even add a new one just to be sure. Thanks so far for all of your suggestions/ideas on this. It's been a real head scratcher. As I get more test information or I find out what the problem is, I will report back here for everyone's future reference.


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## BobearQSI (Dec 3, 2008)

Yes, reverse polarity can both trip the breaker and cause electrical shock. This is much more common with newer equipment as well. Here's why:

In the newer equipment, the connectors are often wired to the neutral wire. In fact, its probably the case that all metal parts on your new TV are directly connected to the neutral wire. I'm not too familiar with TVs, but this is how amplifiers, DVD players, etc are wired. You can easily check this with your multimeter: With the TV unpluged and no where near a socket, and your multimeter on ohms or continuity, connect the multimeter to the big prong of the TV's plug (the neutral). Now try touching metal parts on the outside of the TV. If the metal is painted, you may have to find spots like screws or holes without paint. See if they're connected. The metal might be connected to ground instead.

However, the ground of the connectors are almost for sure hooked up to neutral. Try the same test, with the multimeter connected to the big prong on the TVs cord, and then put the other end on the outside of any connector, like the cable TV input you got shocked from, or the outside of the RCA audio/video connectors. It should show that there is 0 resistance.

Now, the cable company has the outside of their cable connected to earth seperate from the wiring of your house. So with the cable itself connected to ground, when you plug the TV into the wall and plug the cable into the TV, you are connecting neutral with earth, which is okay. Now, if your outlet is reversed, you are making a direct connection from hot to earth through the cable TV connector. Thus, the circuit will be thrown.

Also, when you are going to hook the cable up, if you touch the cable connector on the cable and on the TV at the same time with your hand, the TV is hot and the cable is earth, just like sticking your fingers in the socket - you will get shocked.

So essentially, with a reversed outlet, when you plug that TV in you are making all the metal on the TV (or just all the connectors, depending on the TV) hot. They are just waiting to find any connection to ground, through you touching it through your body, or through a connection like the cable line. Another example is if you have something connected to another outlet that is wired correct. Say, for example, your DVD player is plugged into a different outlet that is wired correct. The audio/video connectors on the DVD player are now correctly tied to neutral. Your TV audio/video connector's outsides are hot because of the reversed outlet. Hook an audio wire between the two, and bingo, a direct connection from hot to neutral. Or, instead of a wire, touch the TV metal and DVD player metal at the same time, and discover a shock.

Older TVs often were not wired this way (and were also less safe when connected to a properly wired outlet).

Lastly, there are many circumstances that can cause a single outlet to be reversed on the whole circuit, some of which were touched upon here. Remember, every outlet (except for the last one) is going to have 4 connections, not just 2. 2 are the connection coming in from the circuit box/previous outlet, and the other 2 are the connections going to the next outlet. If the incoming connections are wired wrong, that outlet will be reversed. If the outgoing connections are wrong, the NEXT outlet will be reversed even though when you look at that outlet, it appears to be wired correct. Also, unless you rip apart the walls, it can be very difficult to see where every single wire goes and it can be easy to miss an outlet on the circuit. Also, you don't know if there's any junction boxes completely inside the walls where the wires are wrong. Even having a schematic of the house doesn't mean the installing electrician didn't screw up, or some previous owner changing things didn't screw things up. Keep looking and examine all 4 connections of every outlet. You also need to know what order they are in, which is difficult as well.


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## Stubbie (Jan 7, 2007)

Look at it this way... the things you mentioned do not have a ground in their power cords and they are not hooked up to an unwanted energized tv coax ground. This means that when the old tv was plugged in it did not have equipment ground in the power cord and there was not a means for the voltage on the coax to seek a ground path and thereby allowing a current flow that trips the breaker. However you did have an energized chassis...you just didn't know it. You never new because you can't come in contact with it. Now with the new tv you have a connection with the metal chassis of the tv and a connection to the ground of the coax. Their is a potential on the coax which now has a direct connection to the grounded conductor through the chassis of the new tv to the equipment ground of the new power cord. If the coax is energized from the branch circuit serving the tv somewhere this becomes a ground fault that is no longer hidden and the circuit breaker will now trip out once you plug the new tv in to the grounded outlet.
The continued mystery is why changing the wires hot to neutral and neutral to hot or vice versa seems to have hidden this ground fault once the new tv has been plugged in. There seems to be a different things going on either you have a floating ground on the coax that is allowing a potential difference to occur and as soon as you connect it there is current flow or you have an energized ground in the coax . What I'm trying to do is to begin a process to eliminate possible causes that may lead us to the solution.
One thing is certain it is not the new tv but an issue with the premise wiring. If it wasn't then the new tv would not have been tripping breakers you would simply plug it in and go on your merry way.....


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## Duane 70 (Sep 16, 2008)

BoBear and Stubbie:
Thanks for the great input. This is maybe starting to make tracking things down a little easier. Just so I understand, if it is a problem with an ungrounded or improperly grounded coax, if I install a proper ground wire, will that solve the issue? If I use a 3 prong to 2 prong adapter for the TV with the wiring put back to the correct locations on the outlet as Theatretech85 suggested, what does tell if anything about a ground problem? Stubbie - what is a "floating ground"?


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## BobearQSI (Dec 3, 2008)

"Floating ground" simply means ground is not connected to anything. You have all the ground wires in your TV, etc, but they are not actually connected to the earth.

The purpose of the ground wire is almost always protection against a malfunctioning product. The chasis of the TV will be connected to the ground wire (or possibly the neutral instead, as indicated in my previous post). Under a normal operating TV, this means nothing. If for some reason your TV malfunctions and shorts out so that it connects the hot to your TVs chasis, then this is where the ground completes the connection causing the circuit breaker to shut off, thus protecting you from the dangers of a hot chasis as I detailed in my last post.

If everything is wired correctly, and you simply don't have a ground wire on that outlet, then it should not make a difference at all. The only difference it would make is if the TV malfunctioned and shorted out.

The suggestion to use the adaptor and therefore 'float' (disconnect) ground is if for some reason the ground has a voltage on it, or is somehow wired weird into the rest of the system.

Do you have a outlet tester? These are cheap (usually < $10) little devices at the hardware store that you plug into your outlet. Here's an example:
http://www.amazon.com/Gardner-GRT-5...ref=sr_1_4?ie=UTF8&s=hi&qid=1228338878&sr=1-4
This device can quickly tell you if an outlet is wired correctly without having to remember which hole means what and how to stick a multimeter in the socket. I'd suggest getting one of these and walk through your whole house sticking it in every socket, and see what problems arise.

How is your outlet currently connected? Remember, the big slot is neutral, the small slot is hot, and the round bottom hole is ground. When the TV works, what is the voltage from neutral to hot, hot to ground, and neutral to ground? (these correspond with the 3 lights on the tester)


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## Duane 70 (Sep 16, 2008)

Update - When I got home tonight I decided to do some checking on this. I took the switch to the TV outlet out to examine the wiring in the box. Found loose connections under the hot wire nut that opened the circuit when wiggled. Twisted those tight and re-nutted. Also did the same with the white wires. All blacks were hooked together, all whites hooked together and ground wires cut off (geesh!!). Completely unhooked the switch and capped the wire. Re-wired the TV outlet correctly (black to brass "to cover my ass"!!!) Tested with multimeter and outlet tester. Both showed correct wiring but open ground on that outlet. Checked the ground with an extension cord plugged into a known grounded and correctly wired outlet on another circuit. Put a 3-2 prong plug adapter on the TV cord and plugged it in. Happy to report that the TV works OK and does not trip the breaker. That apprears to be telling me that something was/is screwy with the switch setup or ground setup or the catv cable. It was dark when I got home so wasn't able to check for proper ground on the TV cable box outside. Also haven't checked continuity, etc. on cable itself inside the house. Any guesses at this time on what the problem was/is??


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## BobearQSI (Dec 3, 2008)

Just to confirm - you used to extension cord to test the polarity, right?

It's not possible to check polarity via this manner with an open ground.

Also, if you have open ground, then the 3-2 prong adapter doesn't really do anything. (FYI, open ground = floating ground).

You should try without the adapter again. If that causes things go bad, then this ground isn't really open (and that's just scary).


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## Duane 70 (Sep 16, 2008)

Yes I used an extension cord to check for proper connections and ground. With the multimeter in the outlet (without extension cord use) the hot to neutral reads 118 v, the hot to ground reads 0 v and the neutral to ground reads 0 v. Using the extension cord from a known correctly wired and grounded outlet I get: hot on outlet to ground on ext. cord = 118 v, neutral on oulet to ground on ext. cord = 0 v. I will have to try the TV cord without the 3-2 adapter. I thought about that - after I aleady pushed the heavy mother back in place. I also used the little circuit tester on the TV outlet and it shows floating ground.


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## rgsgww (Jul 5, 2008)

Duane 70 said:


> Yes I used an extension cord to check for proper connections and ground. With the multimeter in the outlet (without extension cord use) the hot to neutral reads 118 v, the hot to ground reads 0 v and the neutral to ground reads 0 v. Using the extension cord from a known correctly wired and grounded outlet I get: hot on outlet to ground on ext. cord = 118 v, neutral on oulet to ground on ext. cord = 0 v. I will have to try the TV cord without the 3-2 adapter. I thought about that - after I aleady pushed the heavy mother back in place. I also used the little circuit tester on the TV outlet and it shows floating ground.



How about ground to ground on extension cord?

Test voltage and resistance.


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## Duane 70 (Sep 16, 2008)

Removed the 3-2 prong adapter and plugged TV cord directly into outlet. TV works OK and does not trip breaker (thank you God!!) Does this lead you guys to any conclusions now?? I will still check ground on the catv cable when I get some daylight and time. I don't think I checked the ground on the outlet to the ground on the ext. cord. Will do that also.


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## BobearQSI (Dec 3, 2008)

rgsgww said:


> Test voltage and resistance.


Of course, make sure you test voltage first. If voltage is 0, then you can test resistance. If you get a voltage, don't test resistance.


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## Duane 70 (Sep 16, 2008)

What should the resistance be?


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## Stubbie (Jan 7, 2007)

I'll give you my best guess. You say you had an open ground at the outlet or maybe you still have I'm not sure if you corrected that or not. You had a ground fault in that outlet box to the metal box (if it was metal) or metal yoke of the receptacle. It could not clear because of the open ground. Your old tv had no ground wire so the fault could not travel to the tv chassis and ultimately to the tv coax where it then would follow the grounding path to the utility transformer to clear the fault. When you changed to the new tv with a ground wire in the power cord this path was completed to the chassis of the new tv. But it still would not trip the breaker as the fault path back to the source still wasn't completed. When you connected the tv coax the fault path was then completed and the fault current used the coax to return to the source tripping the breaker.
Somewhere in your work you corrected the ground fault and now things are fine.
Thats the best I can do without seeing the situation .


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## rgsgww (Jul 5, 2008)

Duane 70 said:


> What should the resistance be?


Depends...should normally be about 0-1 ohms.


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## BobearQSI (Dec 3, 2008)

Duane 70 said:


> What should the resistance be?


With a normally wired outlet, voltage should be 0 and resistance should be very low, and most multimeters will actually be off a little at this low value, but 0-3 ohms is in the target range, depending on the length of the wire to ground and the accuracy of your meter.

However, if your outlet is truly just an open ground, voltage should be zero and resistance should be infinite (ie, no connection).


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## BobearQSI (Dec 3, 2008)

Stubbie said:


> Somewhere in your work you corrected the ground fault and now things are fine.
> Thats the best I can do without seeing the situation .


I agree. From the description of your problem, it sounds like reversed polarity. However, you said that now you put everything back and just tightened some loose (but not exposed) hot wires. So my best guess is the same, that somewhere along the line you inadvertently fixed the problem.



Duane 70 said:


> I'm wondering if by removing the wire the on the outlet from the switch, making the outlet non-switched, was actually the thing that corrected the problem?


It sounds like you did some re-wiring to bypass the switch . . . maybe during part of this you corrected it? Also, if the wires were reversed upstream in the line somewhere, everything downstream could be the right color wires and screws and still be reversed polarity, so you could have missed something along the way because of that.


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## Duane 70 (Sep 16, 2008)

Yes, it seems somewhere I corrected the problem. The outlet still shows a floating ground. All other outlets on that circuit show good ground - both with the little circuit tester and the multimeter. Everything is wired correctly, black to gold, etc. The outlet box is plastic and the switch box is metal. I guessing it was somewhere with the switch box or switch wiring. I completely disconnected the switch out of the circuit. Now everything is direct wired to the outlet(s). One issue could have been that instead of running proper wires (insulated) from the switch to the outlet for the switched half of the outlet, they used 14/2 NM cable and just wrapped elec. tape around the ends of the ground wire in the NM cable and used that ground wire for the hot wire from the switch to the switched half of the TV outlet!!!! I have disconnected that wire from the circuit. Of course they also nice enough to cut off the ground wires in the switch box so I can't reconnect the ground to the TV outlet. Thanks everyone for your time and help with this problem. I would probably still be scratching my head if weren't for you folks knowledge and help.


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## rgsgww (Jul 5, 2008)

Duane 70 said:


> Yes, it seems somewhere I corrected the problem. The outlet still shows a floating ground. All other outlets on that circuit show good ground - both with the little circuit tester and the multimeter. Everything is wired correctly, black to gold, etc. The outlet box is plastic and the switch box is metal. I guessing it was somewhere with the switch box or switch wiring. I completely disconnected the switch out of the circuit. Now everything is direct wired to the outlet(s). One issue could have been that instead of running proper wires (insulated) from the switch to the outlet for the switched half of the outlet, they used 14/2 NM cable and just wrapped elec. tape around the ends of the ground wire in the NM cable and used that ground wire for the hot wire from the switch to the switched half of the TV outlet!!!! I have disconnected that wire from the circuit. Of course they also nice enough to cut off the ground wires in the switch box so I can't reconnect the ground to the TV outlet. Thanks everyone for your time and help with this problem. I would probably still be scratching my head if weren't for you folks knowledge and help.



Thats exactly what I thought they did!

Makes more sense, the coaxial sheild is bonded with the ground in the tv, the 120 is going into the ground of the tv, finds its way through the coaxial.

Well, you need to install a ground somehow...do you have an attic above this space?

If you leave it like it is, you need to swap the 3 prong with a 2 prong outlet or install a gfci.


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## Ultrarunner2017 (Oct 1, 2008)

What you said about using the bare ground wire as a hot is really scary, but I can believe it!
Some people who do wiring in their homes shouldn't be touching the stuff. That's why we have professionals and inspectors!

After reading in your posts about "hot chassis", I did some testing of my equipment. I get no connection between neutral and any of the external jacks on my stereo receiver, DVD player, or TV.

As I recall, "hot chassis" TV sets came into existence when manufacturers stopped using heavy transformers. They literally used line voltage for the "low voltage" circuits, since there wasn't anything as low as we use today with microprocessor controls, etc.
The chassis was connected to the neutral prong on the plug (and a polarized plug was used)

Those TV's had to use plastic components on the outside, as well as plastic shafts on all the controls to insure the user would not be shocked if the TV were plugged in incorrectly, creating a true hot chassis condition.

These old sets never had any line input or output, just an earphone connector, which was isolated using a small transformer to protect against having line voltage on the headphone cord, so there weren't any issues with connecting grounded cables to the TV and possibly causing a short.

I do not know the construction of LCD TV, so I don't know whether they are using transformers again, or still live chassis with zener diodes and transistor regulating circuits to get the desired low voltages used in these sets.

If your new TV set has a ground prong on it's plug, I would assume that it is connected to the chassis of the set. Anything else would be foolish.

The rest of you have already covered all of the possible scenario, so I won't go back there.
I will say though, that if this were my bran-new expensive LCD set, I would not plug it into a malfunctioning receptacle.
The set has a grounded cord and plug for a reason. By plugging it into an ungrounded receptacle, you are compromising both your safety and that of the TV set.

I would be using surge protection for such an expensive TV set. I use them on all my computer and audio/video components.
Without a properly grounded receptacle, you cannot get adequate surge protection.

You really need to have an electrician in to fix this situation, or if you are competant and comfortable with electricity, do it yourself.
In the mean time, run a heavy guage (Air cond type) extension cord from a known good receptacle, and plug the TV into it.
While I do not recommend the use of an extension cord as a permanent fix, I would use it temporarily as long as it's the heavy duty type with a ground, and it is run in a completely exposed area (not under carpeting, etc) and not near any heat generating devices, or in an area that it could be tripped over, or damaged in any way.


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## BobearQSI (Dec 3, 2008)

KE2KB said:


> I do not know the construction of LCD TV, so I don't know whether they are using transformers again, or still live chassis with zener diodes and transistor regulating circuits to get the desired low voltages used in these sets.


Any modern digital (like LCD) TV is going to have a transformer right at the power input connected to a switching power supply that probably has a couple different voltage rails coming off of it.



KE2KB said:


> I did some testing of my equipment. I get no connection between neutral and any of the external jacks on my stereo receiver, DVD player, or TV.


Also, in newer equipment, I've always seen the shield side of the jacks connected to neutral. The reason is so that multiple pieces of equipment have the same ground reference for their signals. This is to avoid issues like ground loops (http://en.wikipedia.org/wiki/Ground_loop_(electricity)). When all pieces of equipment are plugged into the same outlet, hopefully through a surge protector, they all then have the same reference to ground.

So yes, it makes sense that older equipment would not bother to tie the connectors into neutral and go around the transformer.

On my 3-prong TV, the chasis is tied to ground and the connectors are tied to neutral.


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## Ultrarunner2017 (Oct 1, 2008)

I find it very surprising that UL would allow anything that is accessible on the outside of the unit be tied to neutral, since a fault somewhere in a neutral line could put the operator right in the middle of a current carrying wire!

The equipment I tested is at least 10yrs old. I'll have to see if I have anything around that's a lot newer and check it's continuity to neutral.
If it is true that the neutral is tied to the shield of the connectors, I would install GFCI receptacles or breakers on all circuits that have such equipment.
That way, at least you are protected from a lethal shock in case something is wrong with the equipment, wiring to or the receptacle it is plugged into.

Sanity check: Let me see if I am thinking correctly here: Will the GFCI trip if there is a problem?

Example 1): Bad connection in neutral at receptacle. Potential on neutral of equipment is higher than ground. Equipment is probably not working properly in this situation, due to the poor connection at neutral.
Operator comes in contact with a part of the equipment which is connected to it's neutral prong, and also to a good earth ground.
Depending on how poor the connection to neutral is, and what the person's skin resistance is, there may or may not be enough current flowing through this poor guy (or gal) to cause the GFCI to trip.
That's OK though, since the GFCI will limit the amount of current that can flow through the person to a non-lethal amount.
This is because when the person is contacting both the equipment's neutral connected chassis or connector and an earth ground, some current will bypass the poor connection (a resistance) in the neutral line at the receptacle.
This current will NOT travel through the receptacle's neutral, thus causing an imbalance between hot and neutral.

Example 2) Equipment is plugged into a GFCI receptacle, but this receptacle is reverse wired.
The receptacle will still function normally as long as the current between hot and neutral is the same.
Operator comes in contact with exposed part of equipment that is supposed to be connected to neutral, but is now connected to hot because of the reverse wiring at the receptacle, and also to an earth ground.
Current through hot wire increases due to the person acting as a small load. Current through neutral does not increase, because current through person travels to earth ground, bypassing neutral in receptacle.
GFCI trips.

OK. Sanity test passed. GFCI will save your life!
I can tell you right now that if I find that I have any equipment where the neutral is connected to any part of the equipment that is accessible to the user, I am going to install GFCI receptacle. If that receptacle trips, I am going to get rid of the equipment!

I've said my piece. Now you can debate me all you want, but it still won't change my thinking on this issue. Nothing should be tied to neutral except the power supply input!


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## Gigs (Oct 26, 2008)

BobearQSI said:


> Any modern digital (like LCD) TV is going to have a transformer right at the power input connected to a switching power supply that probably has a couple different voltage rails coming off of it.


I have never seen consumer electronics use a transformer before an SMPS. It's either/or.


Neutral should not be connected to signal shields in devices, that's one good way *create* ground loops, not prevent them.


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## Ultrarunner2017 (Oct 1, 2008)

Gigs said:


> I have never seen consumer electronics use a transformer before an SMPS. It's either/or.
> 
> 
> Neutral should not be connected to signal shields in devices, that's one good way *create* ground loops, not prevent them.


Right. The transformer is part of the switcher, and isolates line from equipment.


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## Ultrarunner2017 (Oct 1, 2008)

To satisfy my curiosity, and preserve my sanity, I checked all of the electronic appliances that have only 2 wire cords, and found a total of zero that have any connection between neutral and any part that is externally accessible. I also checked for capacitance on some of them, and found only nanofarads there, which would not conduct enough AC to cause an issue.

Someone, please give me an example of any piece of equipment built within the last 20 years that has it's neutral tied to anything external, whether it be the chassis or a connector.


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## rgsgww (Jul 5, 2008)

KE2KB said:


> Someone, please give me an example of any piece of equipment built within the last 20 years that has it's neutral tied to anything external, whether it be the chassis or a connector.



An electric dryer.


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## Ultrarunner2017 (Oct 1, 2008)

rgsgww said:


> An electric dryer.


Sorry (buzzz), that's not even in the same category as a TV. It's either hard wired or connected through a special plug on a dedicated line.
I'm looking for something along the lines we were discussing here.


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## Ultrarunner2017 (Oct 1, 2008)

It appears, at least to me that the OP's problem is that his ground was hot.
It may not be now, since he has been working on the circuit, but originally it seems likely that is what caused this whole mess.
Hot ground, connect CATV line (grounded) and sure enough, blow the breaker.

Now he said he's got an open ground, so that's much better than a hot one!


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## BobearQSI (Dec 3, 2008)

I haven't the time to respond fully at the moment, but just list my equipment for now.
My definition of continuity: My multimeter reads 0.3 ohms or less. (http://www.bkprecision.com/products/categories/sub_categories/models/?model=388B)
1) Onkyo TX-SR605 Amplifier/Receiver, released April 2007 - with everything unplugged, the neutral prong on the plug shows continuity between the entire chasis of the unit and the shield of every connector. The whole thing is almost entirely metal.
2) Toshiba HD-A20 DVD player, released some time in 2007 - neutral prong shows continuity between the entire chasis and all the shields.
3) Panamax M4300-PM surge protector - neutral prong shows continuity of the entire chasis. It also has a metal binding post on it called 'grounding post,' that is NOT continuous with neutral, but rather the ground pin of the power plug.

Also, because the receiver has neutral on all input/output shields, anything connected to the reciver is also going to get connected to neutral through the shield.

Tonight, I will re-test all of my equipment, 90% of which is pretty new, and report all models and their findings. I did all this testing about 4 months ago, and I'm pretty sure I remember the results, but I will double check tonight.

EDIT: THIS IS ALL WRONG, see my later post.


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## Gigs (Oct 26, 2008)

KE2KB said:


> Someone, please give me an example of any piece of equipment built within the last 20 years that has it's neutral tied to anything external, whether it be the chassis or a connector.


Modern switching power supplies have input capacitors like this:

Hot----||----Ground----||----Neutral

This will always leak a few milliamps, sometimes enough to trip a GFCI.

The capacitors are class Y which means they are rated for cases where failure can lead to a direct chassis ground fault (hot-ground), risking electric shock.

Capacitors that are line-neutral are class X, rated for hot-netural.


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## Gigs (Oct 26, 2008)

BobearQSI said:


> Tonight, I will re-test all of my equipment, 90% of which is pretty new, and report all models and their findings. I did all this testing about 4 months ago, and I'm pretty sure I remember the results, but I will double check tonight.


Are you... completely unplugging the equipment first?

You do realize that if it's plugged in (or anything connected to it is plugged in), you will get continuity from the ground bonding at your service panel, right?

The only proper way to test this is to completely disconnect all the power *and signal* cables. 

I think this is where your confusion comes from. Even if you unplug say your DVD, if it's got coax to a plugged in TV, you will see ground-neutral continuity.


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## Ultrarunner2017 (Oct 1, 2008)

Gigs said:


> Are you... completely unplugging the equipment first?
> 
> You do realize that if it's plugged in (or anything connected to it is plugged in), you will get continuity from the ground bonding at your service panel, right?
> 
> ...


I got the impression that he was checking with the device unplugged, measuring from the neutral blade of the plug to chassis.

I guess things have changed since the last time I purchased electronic equipment, as none of my equipment is less than 10 years old.
There is one exception though; A Canon multi-function printer. It doesn't even have a polarized plug, and of course there is no continuity between either blade and anything metal on the device.

With this configuration being approved for electronic equipment, I would think that a GFCI receptacle should be mandated for every receptacle in the house, since such equipment could at any time cause a lethal shock if the conditions are right (as I discussed in my previous post).

Oh yea; One thing I forgot to ask; Are you living in the US? If not, then all bets are off! I know that other countries have different wiring configurations. If the power delivery system does not use a ground reference, you have no connection between either line conductor and ground, so there isn't such a risk if something gets "hot".
All of us (who understand power delivery systems even to a small degree) know that without that connection to ground on one side or the CT of the transformer, you have no issues when someone comes between either conductor and earth. Wouldn't it have been nice if our POCO's had done this from the very beginning! Of course we all know why they did use the ground as a conductor $$


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## Gigs (Oct 26, 2008)

KE2KB said:


> Oh yea; One thing I forgot to ask; Are you living in the US? If not, then all bets are off! I know that other countries have different wiring configurations.


No country would ever allow any device to directly tie current carrying neutral to the chassis ground. He's testing it incorrectly or misinterpreting the results or something.

The IEC grounding classes are international, and none of them would allow this.


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## Ultrarunner2017 (Oct 1, 2008)

Gigs said:


> No country would ever allow any device to directly tie current carrying neutral to the chassis ground. He's testing it incorrectly or misinterpreting the results or something.
> 
> The IEC grounding classes are international, and none of them would allow this.


I agree with you, yet I am intrigued by all of this.
Perhaps they are taking ohmmeter readings while the device is connected to grounded CATV or other external wiring, and measuring between chassis and the neutral slot of the receptacle.


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## Gigs (Oct 26, 2008)

KE2KB said:


> I agree with you, yet I am intrigued by all of this.
> Perhaps they are taking ohmmeter readings while the device is connected to grounded CATV or other external wiring, and measuring between chassis and the neutral slot of the receptacle.


That's what I was thinking, somehow they were seeing the neutral bonding at the panel.


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## BobearQSI (Dec 3, 2008)

Okay, so I don't know what I must have been smoking 4 months ago. Neutral is NOT tied to any of my chasis or connectors. I was trying to find the source of a ground loop problem that could only be heard when HDMI devices were plugged into my receiver/amp. I thoroughly analyzed everything. I eventually determined it was a problem with the amp, and sent it in for service and got it back fixed. All I can think of is that neutral being connected to the chasis was the problem with the amp, and they fixed it. I explicitly remember holding one end of the multimeter to the large end of a 2 ponged only plug on my amp, and the other to all the connectors. I'm pretty sure I wasn't seeing ground/neutral binding at the panel, because I was testing both hot and neutral with all sorts of parts on the equipment, and that wouldn't have gone well where other things connected through to a live outlet. Plus, the resistance from neutral to ground at the socket is about 2 ohms rather than 0.2, I'd hope I'd have noticed that.

Anyway, I re-tested everything tonight, and nothing was connected to neutral at all. All devices with 3 prong sockets had their chasis and all connectors hooked to the ground pin. All 2 prong sockets had floating ground/chasis. Sorry for the mis-information here. You all must have felt like this guy: http://xkcd.com/386/
Yes, I do live in the US, too.

Secondly,


Gigs said:


> I have never seen consumer electronics use a transformer before an SMPS. It's either/or.


I don't know of any electronics SMPS that doesn't have a transformer. They usually convert AC current to DC and/or AC current of a lower value. Maybe the confusion what how I said it, what I meant was 'a transformer is usually part of a SMPS.' An example is the first picture here: http://en.wikipedia.org/wiki/Switched-mode_power_supply where the transformer is clearly labeled.

So, back to the original issue with Duane's TV and wall socket, I think I now may know what the problem could have been: The bare hot wire was probably touching some part of a screw or other ground on the actual outlet itself. He said the box was plastic, but sometimes the metal screw connecting the outlet is long and is exposed inside the box. That would make the ground pin hot through the screws in the receptacle. And obviously no ground wire because the ground and hot could touch.

The ground was hot, thus the TV chasis was hot when connected, and then connected to CATV's seperate ground when plugged in. The problem is gone now because after re-wiring, the hot wire is no longer touching the screw or outlet other than where it should be.

Duane, I think everyone agrees here that this bare hot wire and no ground needs to be fixed permanently. If it even barely touches the screw, the same thing will happen again. You said there was tape around the wire, was that both ends (at the switch and the outlet)? Either way, its not good on many levels to have a bare hot wire running behind the wall, probably touching insulation, possibly nails, or who knows what.


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## BobearQSI (Dec 3, 2008)

KE2KB said:


> I agree with you, yet I am intrigued by all of this.
> Perhaps they are taking ohmmeter readings while the device is connected to grounded CATV or other external wiring, and measuring between chassis and the neutral slot of the receptacle.


Also, no CATV here. Just satellite and a small, self-built antenna, neither of which is grounded to earth. Unless my roof has grounded metal hiding in it. They are grounded through the surge protector, though, but like I said, my testing of hot to chasis wouldn't have gone well if stuff was plugged in.


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## Ultrarunner2017 (Oct 1, 2008)

BobearQSI said:


> Also, no CATV here. Just satellite and a small, self-built antenna, neither of which is grounded to earth. Unless my roof has grounded metal hiding in it. They are grounded through the surge protector, though, but like I said, my testing of hot to chasis wouldn't have gone well if stuff was plugged in.


I thought sat systems were always grounded to earth before the line enters the house. Are you sure yours doesn't have a ground wire running down from the dish?
IMO, it should be grounded to protect you and your equipment against lightning surges (not even a direct hit).
During storms, you can get some pretty heavy currents flowing through ground wires. In your case, the current would have to flow through the shield of the coax into your home before finding a ground. That could conceivably cause a fire.
Same reason all of my amateur antenna were (no longer have them up) grounded by rods as close to the antenna as possible.
It is also important from an RF point of view. More important for transmitting antenna than receiving though.

I recall once reading a story by Ansel Adams. He was standing on a beach in CA, photographing a storm coming over the cliffs, or maybe it was coming in over the ocean, not sure.
He thought it was time to get out when his tripod started to get warm!
The tripod was conducting a heavy current from the atmosphere due to the approaching storm.


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## Duane 70 (Sep 16, 2008)

Thanks guys. Just to clarify about the hot ground wire. What the original wirer did was use the ground wire encased in the 14/2 NM cable sheath as the hot connection from the switch to the outlet (only half of the outlet was switched). Where the ground wire exited the NM cable, they wrapped black elec. tape around it for insulation. I as far as I know, the configuration was like for the 30 years the house has been built with no problems manifesting themselves until I plugged the 3 prong cord on the new TV. I recall if anything else with a 3 prong cord was ever plugged into the outlet or not. When I decided a couple of nights ago to pull the switch to see what was inside the box, I could hear some sparking going on. When I pulled the wires from the box, there was a short section of exposed bare "ground" wire that the tape was not covering. I don't know if that exposed section of wire was contacting anything else in the box or not. Also, when I wiggled the wire nut on the black wires, I could hear sparking. I turned of the breaker and removed the wire and found the connections were loose. The switch was wired to the outlet as follows: a short jumper wire (again a piece of bare ground wire wrapped with elec. tape for insulation) from the hot wire nut connection to one terminal of the switch; from the other terminal of the switch - the ground wire in the NM 14/2 cable from the switch box to the outlet box was taped with black tape from the cable sheath to the switch for insulation (this tape was also fairly loosely wrapped). From the switch, the ground (now "hot") wire travels in the NM cable sheath to the gold screw on the top half of the TV outlet. The outlet end of the ground (now hot) wire is also wrapped with black elec. tape. So it seems somewhere, somehow, the wire from the switch to the outlet must have been making contact somewhere it shouldn't have been. I removed the short jumper wire in the switch box completely and re-twisted and re-nutted the black wires in the switch box (also re-twisted and re-nutted the white wires). I also removed the taped up "ground" wire from the outlet and re-taped it up. That wire is now not connected at anything at either end (switch box and outlet box) so I no longer have a switched outlet (just a switch in a box that is not conneted to wires). I also replaced the outlet itself with a new one because the old had the tabs between the screws removed so that only one half (the top half in this case) would be switched. Does this help clear up anything I confused folks on earlier or make things any more sensible?? Thanks again for all of your help and suggestions.


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## Gigs (Oct 26, 2008)

Duane 70 said:


> What the original wirer did was use the ground wire encased in the 14/2 NM cable sheath as the hot.



I'm glad you called him a wirer and not an electrician. Whoever that guy is, he should be sued into oblivion.

Call an actual electrician to check every box and circuit in your house. I could not sleep at night knowing that kind of wiring was in my house. It might cost a couple hundred bucks to have him check over everything, but it'll be well worth it.


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## Gigs (Oct 26, 2008)

BobearQSI said:


> Anyway, I re-tested everything tonight, and nothing was connected to neutral at all.


Yeah it could have been one faulty device confusing you.



> I don't know of any electronics SMPS that doesn't have a transformer.


That's right, they all have a transformer. It's a high frequency transformer that operates around 30 to 60 kilohertz though, it's not doing anything to the line power.



> They usually convert AC current to DC and/or AC current of a lower value.


Transformers are always AC to AC devices. Saying AC current is like saying ATM machine. Sorry I'm being pedantic. 



> Duane, I think everyone agrees here that this bare hot wire and no ground needs to be fixed permanently.


I agree there.


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## BobearQSI (Dec 3, 2008)

Gigs said:


> It's a high frequency transformer that operates around 30 to 60 kilohertz though, it's not doing anything to the line power.


Right, the point I was making when I originally brought it up was that the transformer isolates everything from DC testing (like resisitance) but still allows current of the alternating type :wink: to flow through.



Gigs said:


> BobearQSI said:
> 
> 
> > They usually convert AC current to DC and/or AC current of a lower value.
> ...


When I said 'They' I meant 'SMPSes.' Re-read as 'SMPSes usually convert AC current to DC and/or AC current of a lower value.' Although, technically, the SMPS I've seen that outputs AC and DC, the AC didn't go throught much more than a transformer, so the AC output side wasn't really going through the SMPS.


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## BobearQSI (Dec 3, 2008)

Duane,

I've replaced wire behind a wall before, although it wasn't power wire, my technique may work for you. Is the wall straight from the switch to the socket?

Here's what I did: completely disconnect the existing wire from both sides. Tie the new wire to one end of the old one. MAKE SURE YOU TIE IT GOOD. Also, you probably can't have a big knot in it. You'll have to figure out some way to connect the wires up and secure them so that when you pull on them hard, they don't come apart. Maybe something like this with each individual strand: http://www.tollesburysc.co.uk/Knots/Carrick_bend.htm and leave more space to wind the wire around itself for better holding, or figure something out, then wrap it all in electrical tape, etc. Next, pull the other end of the wire out of the wall so that you pull the old wire out of the wall and the new wire through the wall.

That's the tricky part - you don't know how small any holes the wire will go through are. Plus, you have to make sure the tied part does not come apart half way through - if it does, you're really SOL.

Once you get the new wire through (make sure it is overly long), cut off the excess and reconnect everything, now with a proper ground.

I'm assuming since you're posting on a DIY forum, that you'd rather get around hiring an electrician if possible. So this is one option that worked for me before, but you do run the risk of the wire disconnecting in the middle, and the smaller any holes inside the wall are or turns, etc, will make it more difficult. And make sure you wire the new socket correctly as well.


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## Ultrarunner2017 (Oct 1, 2008)

I agree with what Gigs said. Call a a real electrician to have your entire house checked out.
You don't know how many other circuits you have wired some crazy way that is just a fire waiting to happen.
Seeing that bare ground wire in the NM used as a hot would have caused me to immediately begin checking every receptacle, switch, light, and anything else that uses electricity in the house.

My burning question: Why in Hell did the guy who wired this use the bare wire as a hot?
It would have made at least a tiny bit of sense (but still be way off being code) if he had used the black and white as the hots, and the bare wire as neutral.
If I could find out who wired your house, I would file a lawsuit today! Then of course, the guy would vehemently deny that he did any wiring, and no one could prove he did.

One further note: Since you have no ground on the receptacle for the TV, you should probably install a GFCI just to be safe.


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## Duane 70 (Sep 16, 2008)

Thanks again guys. I have already replaced all of the outlets and switches in the house and all appreared to be wired correctly. The reason I replaced everything was because the outlets were back-stabbed and I'm sure all of youl electricians know what happens to back-stabbed connections after a few years. I had a bedroom circuit quite working because of a loose back stab connection. Then the wife decided she wanted white outlets/switches instead of almond - so everything got changed. I didn't find anything like the ground wire fiasco in the switch box for the TV outlet. Yes, probably a good idea to up a GFCI in the TV outlet box now.


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