# Unfused connectors MELTED House wires WHAT TO DO???



## jamiedolan (Sep 2, 2008)

HI;

**I could really use some help from the experianced folks on this one, as the liceansed electrician was just lost in terms of knowing what wires are safe** Thanks in advance.

This is a true story about what happened to my dad and his house last night when working in his panel. This shows just how dangerous working around unfused service conductors is, even with your panel off. My dad is very lucky that there was no arc flash of any size. No one was injured, luckly, but it could have easily been a very different story.

My dad was trying to trace some circuits in his panel, with the main pulled. I don't know exactly how it happened, I wasn't in the basement at the time. Thank god he was using one of my klien insulated tools. He someone had a #4 awg bare wire that was connected to the water meter contact a unfused service conductor. This energized every metal part in the house. It melted through the clamp on the water meter cutting a hole in the pipe, flooding the basement. 

I suspect that the circuits on other leg of the panel, not the one he made contact with became energized with 240V +/- any resistance from items on these lines.

As soon as I realized he had energized everything metal in the house, and wires were smoking and melting, I demanded he get away from the house and I would not even let him pull the meter because everything was energized. Calls to 911 and to the power co for an emergency dc at the pole were made.

It took the power co almost an house to dc at the pole and remove the meter. The entire time wires were melting and smoking. A number of the romex wires in the basement had the insulation melt and drip off the wires. 

After the power co came and the fire dept cleared the house as safe, and the water got shut off at the streetWith power off at the pole ; I tested contunity between the neutral and hots. 4 or 5 of the circuits had continuity. 

A liceansed electrican was called and came out. He grounded the system, to a old rod (one that was never connected to the electrical system) and rebonded to what was left of the water pipe. He did not replace the SE cable or anything else. He then had the power co restore power. I have all the breakers off, except for 2, where I put new wire in for the furnace and a utitilty outlet at the panel.

I asked the electrician, about how we can know if any of the wires in the house are safe or useable. I asked him about meggering he knew what it was but didn't have access to the equiptment to do it. 

I know much is going to have to be rewired. This is a house from around 1917, very hard to fish wire in. 

My question here is, If some of the branch circuits appear to look good physically, and I test the continuity on the wires with a sensetive meter, would that tell us the wire is safe to use? My concern is that the insulation may still be partially melted through, and there is a arcing hazard later on when there is a load on the branch circuit. Would Meggering actually tell us if they were safe to use? 

The liceansed electrican just didn't know, and he was going to just turn on all of the branch ciruits that were not dead shorting. I was not comfortable with that at all, and I turn off everything, but the 2 circuits I did with fresh wire.

Do you think there is any chance of using any of the old wire safely? Do you think that the wires that were on the leg of the panel that got grounded out would be more likely to be ok, since they were not fed 240?

What would you guys do in this situation. It is a large 3,000sqft old house, very difficult to fish wires in. I bet this is going to be 10,000-20,000$ if the whole house needs a rewire due to the complexity of the wire fishing.

Any thoughts are greatly appriciated. 

*AGAIN FOR THE RECORD, AS I KEEP TELLING PEOPLE; UNFUSED SERVICE CONDUCTORS ARE VERY DANGEROUS, STAY AWAY FROM THEM IF YOU DON'T FULLY UNDERSTAND WHAT YOUR DOING!!!*

Thanks guys,

Jamie


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## joed (Mar 13, 2005)

I not replacing all the wires then meggering is the only test I would trust.
I would count on rewiring the entire house.
If you choose to go that way, your insurance will probably cover this repair.


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## Yoyizit (Jul 11, 2008)

Only the wires with crispy insulation carried heavy current. If the current was that heavy, smaller wires that carried heavy current would already read as an open circuit.

I think that during the short, the voltage applied to the rest of your house was less than 1v.

The fusing current, and power, for a copper pipe containing water must be enormous. Maybe people on a physics website could calculate this. I think your panel can deliver 240kA so it would be some current less than this value.
#6 copper melts at 700A.

I would imagine that insulation heated this hot would read higher megohms than normal.


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## jamiedolan (Sep 2, 2008)

Yoyizit said:


> Only the wires with crispy insulation carried heavy current. If the current was that heavy, smaller wires that carried heavy current would already read as an open circuit.
> 
> I think that during the short, the voltage applied to the rest of your house was less than 1v.
> 
> ...


Thanks for responding.

So what would have determined which circuits took a hit and didn't? Would it have been a matter of what devices where on the circuit and there resistance?

Thanks
Jamie


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## AllanJ (Nov 24, 2007)

What you had was a short circuit from the unfused terminal in the panel down the #4 wire to the clamp and pipe. From the latter location some current will go to ground where the pipe exits the house but if there is another path, back to the panel ground, current will also take that.

Are (ground) wires clamped to pipes anywhere else in the house? If so, those circuits would need more investigation in case large short circuit current used the plumbing system and then used their ground wires to get back to the panel.

Are the melted wires just at the panel (physical as opposed to electrical heat damage) or does the damage extend several feet?

Meanwhile simply making the neutral or ground wires hot with 240 volts because a hot wire touched the panel grounding bar it is not going to fry the branch circuits. There must be a flow of current from one place to another for example the wire in question was grounded in one place and energized in another place.

The pipe got melted at the pipe clamp because there was not all that good a connection where the #4 wire was clamped on. Good enough for maybe 20 amps of current from a short from a breaker protected branch circuit but not for what may have been 1000 amps (limited only by the pole transformer fuse) from the unfused contact in your panel.

When testing for continuity to prove the existence of a short in a branch circuit, don't forget to unplug everything from that circuit. An incandescent light bulb will test only a few ohms since the resistance of the filament is very small when the filament is not hot.


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## jamiedolan (Sep 2, 2008)

AllanJ said:


> What you had was a short circuit from the unfused terminal in the panel down the #4 wire to the clamp and pipe. From the latter location some current will go to ground but if there is another path back to the panel current will also take that.
> 
> Are (ground) wires clamped to pipes anywhere else in the house? If so, those circuits would need more investigation in case current used their ground wires to get back to the panel.
> 
> ...


I was concerned that something could arc and start a fire without opening a breaker, I thought that might be even a greater concern with the knob and tube. Since the house wiring is old most is not grounded. So if it was shorting to say a metal box due to melted insulation, then the breaker would not open if that box is not grounded. Thats my concern.

There is atleast 15-20 feet of nm/ romex going across the room that is just melted, it had no direct contact with the fault in the panel, other than being connected to the neutral bar. 

I am going to pull some more suff apart this afternoon and physically how far from the panel stuff has melted.


If I connect the hot and neutral on a circuit at the far end, and test from the panel, I should see a very very small ohm reading, even with a somewhat long run, correct? Would I just estimate the distance of the run and multiply it by 0.000078 per foot? and see if I get close to that reading on a ohm meter? How accurate of a test would that be? 

I may have to buy a Fluke 1587 or similar.

Thanks
Jamie


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## micromind (Mar 9, 2008)

The only way I know of to judge the integrity of any cable is to megger it. 

This test applies a high DC voltage (for house wiring, I'd use 1000 volts), and measures the current on the return. A couple of milliamps would be acceptable. The idea here is that if a circuit can stand 1000 volts and not leak more than a few milliamps, it'll stand 120 volts with much less leakage. Usually, we megger at twice the insulation rating.

I would first unplug everything in the house, remove all light bulbs, turn on all switches, and megger each circuit at the panel. Anything that loads a circuit must be disconnected. Smoke alarms, etc. First test the circuit with a basic ohm meter, if it shows open then megger it. If it doesn't read open with an ohm meter, it certainly won't pass a megger test. Megger from hot to neutral, hot to ground, and neutral to ground. Grounds do not need to be disconnected. 

Any circuit that reads less than a few milliamps is considered safe, it's pretty common to read less than 1 microamp.

Rob

P.S. The only circuits that should have been affected are ones that connected to things that were grounded by other than the electrical system. If the furnace is gas and its wire is cooked, check the gas piping carefully; it carried substantial current.


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## InPhase277 (Feb 9, 2008)

I'm sorry to hear about your troubles Jamie. At least now you have a real world example of what we have been telling in theory.

As others have said, megger, megger, megger! As far as the K&T circuits, it is unlikely they took any damage, because they are ungrounded and the current that did the damage was flowing on ground wires, otherwise the water pipe ground would not have caused any damage except at the water clamp. 

Your old man was quite lucky he didn't get his face burned off!


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## micromind (Mar 9, 2008)

The actual current flow here is likely a lot less than you think. 

As an example, lets assume the POCO transformer is 50 KVA. That's actually pretty good sized for a house, but somewhat normal for a bunch of houses fed from one transformer. The typical impedance for such a transformer would be around 4%. At 240 volts, 50 KVA = 208 amps. 208 amps divided by 4% = 5200 amps. This would be the current that the transformer could produce if the 240 volt side were shorted out at the terminals and the the high voltage side were maintained at rated voltage. 

This 5200 amp figure is at the transformer, and doesn't account for current losses in the line from the transformer to the house. 

In reality, most houses that are fed overhead, and not far from the POCO transformer will come out between 1000 and 4000 amps of short-circuit current. If the feed is underground, and the transformer is close to the house, figure 2000-5000 amps. It's extremely rare to have a single-phase service that can produce more than 10,000 amps.

It's amazing what a few thousand amps of current out of control can do though. Imagine what can happen in an industrial building with a 480 volt service capable of 30,000 amps!

Rob


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## InPhase277 (Feb 9, 2008)

micromind said:


> It's amazing what a few thousand amps of current out of control can do though. Imagine what can happen in an industrial building with a 480 volt service capable of 30,000 amps!
> 
> Rob


Oh, brother! I wish I had some pics of some of the burn downs I've seen. The one that sticks in my mind in particular was when a couple of maintenance guys ran a lift up into a 12,470 V bus. It just showered molten metal what seemed like forever. The guys weren't hurt very badly because they were getting the hell out almost the time they realized what they had done! They had some pretty good burns but the lift was toast.


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## joed (Mar 13, 2005)

> If I connect the hot and neutral on a circuit at the far end, and test from the panel, I should see a very very small ohm reading, even with a somewhat long run, correct? Would I just estimate the distance of the run and multiply it by 0.000078 per foot? and see if I get close to that reading on a ohm meter? How accurate of a test would that be?


The main problem here is not the open wires. They will be easy to find. The problem is the cables with wire intact but insulation damage that arc or short in the future. That is what a megger test should find. It is a test with each wire disconnected. High voltage is applied between the wires testing for arcing and current flow.


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## jamiedolan (Sep 2, 2008)

InPhase277 said:


> I'm sorry to hear about your troubles Jamie. At least now you have a real world example of what we have been telling in theory.
> 
> As others have said, megger, megger, megger! As far as the K&T circuits, it is unlikely they took any damage, because they are ungrounded and the current that did the damage was flowing on ground wires, otherwise the water pipe ground would not have caused any damage except at the water clamp.
> 
> Your old man was quite lucky he didn't get his face burned off!


Well, I have an update. I went over and did further investigation into what happened. The wiring in his house is sure a jumbled mess. I found that there is actually only one piece of romex that in all twirled around in the ceiling that melted. I also checked the old 4awg grounding cable that was removed and replaced to the water meter. The 4awg cable had almost 0 resistance, and it appears to be intact (it is in a mc type jacket). 

After talking to my dad, and looking at where clamps were and such. I finally figured out what happened. 

That 4awg wire shorted to leg of the panel, but the bond to the water meter stayed in tact, and was the path of least resistance to ground for the current (I assume it was the least, because the other choice would be to flow through the house wires, which are mainly ungrounded).

Upon closer examination once things were cleaned out, the water pipe was not actually severed as I first thought happened, It appears that the leak is not where the grounding clamp was, it was where the copper pipe jointed the lead pipe. So the current flowed through the copper 4awg to the copper pipe to the lead pipe -- lead pipe had more resistance, pipe heated up, and the joint loosened?? or caused pressure to build in the pipe and broke the connection? Possible?

As to the romex NM that was all burnt, I figured out that that cable much have been in direct contact with the ground wire to the water meter, which, must have become very very hot, which melted the romex outher sheathing, then caused a short in the cable.

Upon inspecting the box more, I highly suspect that the wires in the box are damaged from the heat that was produced by the fault.

In other areas of the house, I can find no evidance of any damage to the wires, other than in the panel and the one 20' piece of romex that is torched that was physically touching the 4awg ground wire. 

I installed a utility outlet next to the panel and pluged in some extension cords. All appliances and computers tested thus far and just fine. 

So, at this point, I suspect that he only damaged the cabled where they come into the panel and that one piece of romex

Do you think this sound right? Don't you think I would have found some evidance of damage elsewhere in the house or blown electronics if any amount of the current ended up flowing back into the branch circuits?

Thaks very much
Jamie


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## 220/221 (Oct 9, 2007)

Homeowners should NOT be messing around in their panels.

I am glad that Dad is OK but...... what a dumbass.:jester:

I don't want to say that you encouraged him because of your new interest and experience with electrical but....:whistling2: 

Again, I'm glad he's OK. Just have him call/pay someone to take care of his electrical. It aint rocket science but you NEED to know what you are dealing with.

I think that your assesment of the damage was probably correct. Tell Dad to do whatever it is that he does so he can be here to enjoy his grandkids.


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## Yoyizit (Jul 11, 2008)

micromind said:


> The typical impedance for such a transformer would be around 4%. At 240 volts, 50 KVA = 208 amps. 208 amps divided by 4% = 5200 amps.


A book by Ray C. Mullin on resi. wiring puts the impedance at the panel at 1 milliohm. Maybe this was a typo. 
I guess I'll measure it sometime.

If you have an AM radio in the middle of the house tuned between stations with the volume turned up, you have a whole-house arc detector. You could test it by slowly pulling out the plug of an incand. lamp that is on. Do this just once.


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## rgsgww (Jul 5, 2008)

Those nasty service conductors...always watch what your doing!


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## joed (Mar 13, 2005)

Those findings make sense to me. I was trying to understand why a ground cable short to ground would burn up branch circuit wiring. I makes sense that a cable run beside the ground cable would burn up along with the ground.
The water pipe probably heated enough to melt the solder and let the water pressure blow the line apart.
Any chance you could post some pictures of this?


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## rgsgww (Jul 5, 2008)

Pictures would be nice.

Maybe this happened. Sorry for poor drawing.


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## frenchelectrican (Apr 12, 2006)

Jamie.,

I send you a PM to let you know that I am still in Paris France right now until end of this month.,


Now let get to the situation you have there .,

WOW.,, your papa is lucky he did not have the house burn down yet.

If I was still in Wisconsin., For sure I can zoom over and help ya.

that was pretty strong short current that make the copper solidering melt and BTW the soilder it will melt about 600~750°F depending on the " tin " itself.

Most POCO transformer can able crank out about 4 to 12 Kamps depending on size of transformer on resdentail area however in commercal the SCA { short circuit amps } it will be much higher it can have much as 30K or more depending on the size.

speaking for rest of wires IMO the best way is megger it. 

I know not all electricians will carry this tester with them.
One thing I know with most homeowner insurance I am sure they have something to cover the damage but how much that part I don't know it pretty much up to them what they written in their policy but I am pretty sure they will cover most of the repair as need to.

I will start at the panel and work it way out after you check all the conductors to make sure they are not damaged at all or any burnt mark on them.

If you have any gas fired devices like furance , waterheater dryer etc etc check the gas system very carefully to see any burnt mark as well especally with SSCT { stainless steel corrated tubing }.

Merci,Marc


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## jamiedolan (Sep 2, 2008)

Homeowners should NOT be messing around in their panels.

I have to say that I really have a new perspective now that I didn't have before and I have to kind of agree with you. Even my old Pushmatic panel wasn't bad at all compared to my dad's mess and I've seen photos of worse. You have to be carefull enough in a good clean panel, but if there is stuff out there like my dads panel wow, you have to have some serious attention to detail to work in a live panel like that. 

 I am glad that Dad is OK but...... what a dumbass.:jester:
I don't want to say that you encouraged him because of your new interest and experience with electrical but....:whistling2: 

Your right, he would not have been messing around in there if I hadn't pointed out that his ground wires in the house were ENERGIZED and that's why my mom was getting that little tingle when she touched the switch. So yes, I am responsiable for it in the sence and do feel bad that I was the one who pointed this stuff out. On the other hand one if one day my mom was walking in bare feet and the floor was wet when she touched a switch... It could have easily been much worse than what happened.

I am so lucky that he was using my pair of Klien insulated pliers or he very likely would have been electrocuted.

Again, I'm glad he's OK. Just have him call/pay someone to take care of his electrical. It aint rocket science but you NEED to know what you are dealing with.

I think that your assesment of the damage was probably correct. Tell Dad to do whatever it is that he does so he can be here to enjoy his grandkids.

That's kind of the problem with my dad, he has been a handyman his whole life and has always felt like he could do things like electrical himself. (he spent a lot of his life in construction, but is really too old to keep up with any larger construction jobs anymore). His work is normally very high quality, but He is very impatient and gets easily frustrated. I am on the other hand obsessive about the details, check everything atleast 3 times, and if I don't know how to do it, I ask / check on it.

I don't think I mentioned this before, this whole thing just scared the $*%# out of me. When this happened, (with the main out), I had a tone generator clipped onto the neutral bar in his panel, the other lead was clipped onto a branch circuit. I was in a upstairs office, At the exact moment this happened, I had just stuck the end of my metal probe on my tone generator into the hot side of a outlet, with the speaker on high. Man did that freak me out, I almost droped dead on the spot, (I thought how the is there this horriable loud booming voltage hum when I have the main pulled, I thought, my dad knew very clearly not to put the main back in, what the $%* ) it was one horrible humming buzzing noise. I am really lucky that the wires that he burned through and shorted out in the panel were not the wires I had the probe on or I could have been electrocuted with my probe... Yet another good lesson, always tag and lock out your work if your counting on it being de-energized. I knew he was not going to put the main back in, he knew I was testing.

He has an insurance adjustor comming out tommrow, and they are hopefully going to pay for someone to come and clean up this whole mess for him.

Jamie


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## jamiedolan (Sep 2, 2008)

rgsgww said:


> Those nasty service conductors...always watch what your doing!


I do watch what I am doing very carefully and can't imagine I would have made a mistake like this. 

If they would only require fused Disconnects at the meter this kind of thing would NEVER happen.

Jamie


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## jamiedolan (Sep 2, 2008)

joed said:


> Those findings make sense to me. I was trying to understand why a ground cable short to ground would burn up branch circuit wiring. I makes sense that a cable run beside the ground cable would burn up along with the ground.
> Tthe water pipe probably heated enough to melt the solder and let the water pressure blow the line apart.
> Any chance you could post some pictures of this?


I am sure it would have all clicked for me much sooner if I had not been so freaked out by the whole event. As you can see in post #19, I explained in more detail where I was when this happened, and how it was a rather close call for me. 

I did shoot some photos with my dad's camera last night, but left it over there, and there is no internet access or computer up and running yet. They are just using extension cords off of the utility outlet I installed late last night for them. (The licensed electrician was just going to leave all the branch circuits on that didn't have direct shorts on them - that scared me).

But will swipe his camera or memory card so I can get some posted in the next day.

Jamie


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## rgsgww (Jul 5, 2008)

jamiedolan said:


> I do watch what I am doing very carefully and can't imagine I would have made a mistake like this.
> 
> If they would only require fused Disconnects at the meter this kind of thing would NEVER happen.
> 
> Jamie


Don't take it wrong, it wasn't directed at you, or anyone. It was just advice for the next reader.


Jamie, I don't think you would ever make a mistake like this.

Scary stuff, you guys are lucky.


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## jamiedolan (Sep 2, 2008)

rgsgww said:


> Pictures would be nice.
> 
> Maybe this happened. Sorry for poor drawing.


That does look like a accurate diagram of what happened. I will get some photos posted. 

Thanks for the drawing.
Jamie


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## mikey48 (Dec 6, 2007)

We all make mistakes including the pros. Don't be to hard on your dad, I am sure he was pretty upset at what happened. Your Dad is Ok, the house did not burn down and you are OK. Many DIY's work on their panel and know what they are doing including myself.


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## jamiedolan (Sep 2, 2008)

Hi Marc;
I send you a PM to let you know that I am still in Paris France right now until end of this month.,
Thanks for sending me the message.

that was pretty strong short current that make the copper solidering melt and BTW the soilder it will melt about 600~750°F depending on the " tin " itself.

Never have I seen a meter spin so fast. It ran like that for a hour. I wonder what the power bill is going to be!!! since it was unfused, I suppose it could have been well over 200 being used. ouch!

Most POCO transformer can able crank out about 4 to 12 Kamps depending on size of transformer on resdentail area however in commercal the SCA { short circuit amps } it will be much higher it can have much as 30K or more depending on the size.

He is over off Wisconsin, In neenah, just a block from down town. So I am not sure what size transformer he would have. 

speaking for rest of wires IMO the best way is megger it. 

I know not all electricians will carry this tester with them.
One thing I know with most homeowner insurance I am sure they have something to cover the damage but how much that part I don't know it pretty much up to them what they written in their policy but I am pretty sure they will cover most of the repair as need to.

He is talking to the insurance in the AM. If they decide it is covered, he has up to 240,000 to cover damages.

I suspect that someone will come in and megger for him due to the situation. However, I'd like to get myself a megger. I posted a message about a couple models I am looking at. 

Do you have a megger you use? 
 
I will start at the panel and work it way out after you check all the conductors to make sure they are not damaged at all or any burnt mark on them.

If you have any gas fired devices like furance , waterheater dryer etc etc check the gas system very carefully to see any burnt mark as well especally with SSCT { stainless steel corrated tubing }.

Merci,Marc

All black iron, no signs of damage there. (one whip upstairs on stove, i'll double check that one for safety) HVAC guy was out and went over it, it had stopped working. Turn out the only problem was that when my dad wired the furnace to the extension cord for a temp hook up, he reversed the polarity on the connections. For some reason this a problem for the furnace and will not allow it to start. But the HVAC guy went over all the furnace stuff and connections and I inspected the rest of the gas pipe.

I wanted to get in there more today and pull more stuff apart and look at more things, but my dad needs to wait till tommrow to see what decisions the insurance adjustor makes about the damage and what they are willing to pay for.

Thanks Marc.

Jamie


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## AllanJ (Nov 24, 2007)

Yoyizit said:


> A book by Ray C. Mullin on resi. wiring puts the impedance at the panel at 1 milliohm. Maybe this was a typo.
> I guess I'll measure it sometime.


We would need the whole paragraph mentioning this impedance to understand the significance. For example if we are talking about voltage drop imposed by the panel, an impedance of one milliohm from the hot service feed for the main breaker through to the hot lead out of a branch circuit breaker would mean unmeasurable voltage drop.

There may be some concern about deterioration of the service pipe from the house to the water main. Considerable current from this short circuit will have gone to ground that way returning to the pole transformer secondary via the ground system and ground wires on the poles . A process called electrolysis, which literally makes the metal (pipe) dissolve, occurs when electricity flows through pipes and into surrounding moist earth. In addition, there may be better conduction to the earth at a few points along the pipe and increased current flow and arcing and melting of the pipe could have occurred underground. Not much you can do about something like this now but don't be surprised if in a few years you have a leak up into the front yard.

Meanwhile back in the house, objects not in contact with both electricity and plumbing should not have suffered damage. For example dryers and non-electric (clockless) gas stoves. Grounded conductors (ground wire in Romex cables, BX cable sheaths, etc.) between any association with plumbing and the main panel are the vulnerable items. You may want to make a sketch of the plumbing to get a better idea of the higher priority places to look.


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## jamiedolan (Sep 2, 2008)

*Update*

Update: The insurance will pay for damages, however, they don't want to pay to bring stuff up to current code. i.e. rewire circuits with a ground. What an expensive mess this is going to be. I hope that if anyone reads this they will think twice about working around unfused service if they are not absolutely certain they know what they are doing and the risks of that kind of work. 

He found an electrician that will megger the wires, and should be coming out tomorrow. Then we will find out for sure how extensive the damages where.

I have my camera and the car and will snap some more photos when I go over and post them later on.

Thanks again guys.

Jamie


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## jamiedolan (Sep 2, 2008)

AllanJ said:


> We would need the whole paragraph mentioning this impedance to understand the significance. For example if we are talking about voltage drop imposed by the panel, an impedance of one milliohm from the hot service feed for the main breaker through to the hot lead out of a branch circuit breaker would mean unmeasurable voltage drop.
> 
> There may be some concern about deterioration of the service pipe from the house to the water main. Considerable current from this short circuit will have gone to ground that way returning to the pole transformer secondary via the ground system and ground wires on the poles . A process called electrolysis, which literally makes the metal (pipe) dissolve, occurs when electricity flows through pipes and into surrounding moist earth. In addition, there may be better conduction to the earth at a few points along the pipe and increased current flow and arcing and melting of the pipe could have occurred underground. Not much you can do about something like this now but don't be surprised if in a few years you have a leak up into the front yard.
> 
> Meanwhile back in the house, objects not in contact with both electricity and plumbing should not have suffered damage. For example dryers and non-electric (clockless) gas stoves. Grounded conductors (ground wire in Romex cables, BX cable sheaths, etc.) between any association with plumbing and the main panel are the vulnerable items. You may want to make a sketch of the plumbing to get a better idea of the higher priority places to look.


Allan, 
A plumber came out today to make the repair. It appeared that the failure point was in the coupler that goes from the copper to the lead pipe. I am not positive, now was the plumber if the failure was a solder joint on that coupler or where it met up with the lead. Water has been on for a couple hours with no signs of leaks. Visual inspection has not revealed any other damage to the water pipes. Hopefully he is in the clear with the water pipe system, but I have warned him about the possibility of hidden damage that may cause a leak at some point in the future. 

I also did pass along your information about double checking the gas pipe and any flex whips (to the oven). I believe that the oven would have been the only gas appliance with a csst whip. Only other gas is the h20 heater and the furnace, which are both plumbed with black iron. 

The electrical service was not directly bonded to the gas pipes, but I am sure it could have easily made the connection via other electrical systems once things had become energized. 

It would be very interesting to see how electricity flowed in a situation like this, and what was energize and with how much voltage. Of course it would have to be done in a lab for obvious safety reasons.

Thanks again
Jamie


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## jogr (Jul 24, 2007)

jamiedolan said:


> Update: The insurance will pay for damages, however, they don't want to pay to bring stuff up to current code. i.e. rewire circuits with a ground.


Since it is impossible to repair without meeting code I suspect they are actually financially responsible for whatever expenses are required to repair the damage including anything required to meet your local codes that are in force for the type of repair work being done. 

For example, if your local code allows 2 wire romex to be used for repair of existing 2 wire circuits then the insurance company could limit their financial responsibility to that (I doubt your code allows that). But if your code requires that all circuits being repaired be upgraded to current codes then I think the insurance company is responsible for that entire cost.

You might want to push back at the insurance company.


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## AllanJ (Nov 24, 2007)

>>> ... why a ground cable short to ground would burn up branch circuit wiring.

One example:

Let's say the water heater has an electronic ignition or an electric vent damper. It is served by a branch circuit with ground wire connected to its chassis. Then fault current flows through the water pipes, reaches the water heater, and uses that #14 gauge or so ground wire to get back to the panel ground. That part of the branch circuit in question back to the panel is now fried by the overloaded and therefore overheated ground wire.

Current is not going to flow through all the pipes, just those between the energizing point (the clamp) and where there is existing metal to metal connection to a ground such as described above. But a voltage "potential" does exist throughout the plumbing system. A person touching any water pipe, faucet handle, etc. and whose other hand or feet, etc. are grounded can be electrocuted.

Since a pipe joint melted open, that is evidence a lot of current went "thataway".

By the way, the voltage involved was 120. Only one of the unfused terminals of the 120/240 volt service was touched by the #4 wire.


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## Yoyizit (Jul 11, 2008)

AllanJ said:


> We would need the whole paragraph mentioning this impedance to understand the significance. For example if we are talking about voltage drop imposed by the panel, an impedance of one milliohm from the hot service feed for the main breaker through to the hot lead out of a branch circuit breaker would mean unmeasurable voltage drop.


In the same chapter he talks about the percent impedance method for determining short circuit current and mentions 20,800A, which would put the impedance at closer to 10 milliohms.

My dryer nameplate says 24A but I can check the 240v current draw with a clamp-on ammeter. I can use another unused 240v line to measure voltage drop at the panel without taking the cover off while having my wife switch the dryer on and off until I get some idea of the drop.

1 milliohm would give me a 24 mV drop, the other would give 240 mV. My meter may be able to resolve a change this small, otherwise I'll have to make a circuit that cancels out most of the 240v, kind of an expanded-scale meter.
If I can get off my butt I'll invest 15 minutes and check it for my house. Other houses drawing current from the same xformer will reduce this Thevenin equivalent impedance.


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## Gigs (Oct 26, 2008)

Yoyizit said:


> In the same chapter he talks about the percent impedance method for determining short circuit current and mentions 20,800A, which would put the impedance at closer to 10 milliohms.


That sounds unrealistic to me, why would we all use 10KA breakers if your home service could short 20KA?

2/0 copper is 0.08 milliohms per foot. 4/0 Al is about the same.

If your service drop is only 20 feet long, that's 40 feet of wire. So you got 3.2 milliohms just in the wire on a short service drop.

And that's not even talking about the impedance of the transformer, which is surely several times that.


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## jamiedolan (Sep 2, 2008)

Well I wonder what the insurance company does about wiring that is so sub standard it doesn't even come close to any codes now or ever. I gutted all the EMT today. I found some really scary stuff. I forgot my camera over there.

The 1/2" emt run to the AC contained 2 #12 and a insulated ground wire, all THHN. It appears at one point the THHN was damaged due to a bad pull. That must have arced and about 20' of the run melted and fused together all 3 strands of the THHN. If it wasn't in EMT the house would have most certinly been on fire if that happened.

Some of the things I have found are too scarey to describe, will have to post photos. 

The electrician that is going to megger the upstaris circuts didn't make it today, but hopefully tommrow.

If what happened in that conduit to the AC happened anywhere else in the house... Well it could have happened partially and just managed not to start a fire, but the wires could still be in very bad shape.

I found that all the Knob and tube is feed off of Romex. Atleast some of the junctions to romex are burried in the walls....:whistling2:

Don't if it I should laugh or cry. :laughing::furious:

Much of this was done by the previous owners, and has been this way for over 3 decades. 

Jamie


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## frenchelectrican (Apr 12, 2006)

Jamie.,

Thanks for letting us know up the speed with the damage ya got on your father's house.

Speaking of Megger I have Fluke Megger { yes there is serveal verison on market } and I got a simple megger which it will give me go or no go with the cables or conductors { It a Amtech but not sure if the company still in bussiness or not }

Merci,Marc


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## Gigs (Oct 26, 2008)

jamiedolan said:


> I gutted all the EMT today.


I know you are anxious, but you might be hurting your ability to make a larger insurance claim here for bringing all the damaged circuits up to code. 

Was there already a permit pulled for work at his house before the accident?

If so, the insurance company is going to be more likely to see your claim as a way to fund the work you were already planning on doing.


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## jamiedolan (Sep 2, 2008)

Gigs said:


> I know you are anxious, but you might be hurting your ability to make a larger insurance claim here for bringing all the damaged circuits up to code.
> 
> Was there already a permit pulled for work at his house before the accident?
> 
> If so, the insurance company is going to be more likely to see your claim as a way to fund the work you were already planning on doing.


NO permit was in place prior to the accident. Was just a simple repair. This all started because I discovered that a ground was energized. My mom complained, "when I touch that switch I get a little tingle". Then in the process of figuring out where that ground was being energized, I was tracing circuits to find out what goes where, with the goal being to find what is connected to the circuit that had the energize ground and to find the fault and repair it. Then my dad was in the panel and we had the accident.

Jamie


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## AllanJ (Nov 24, 2007)

Gigs said:


> That sounds unrealistic to me, why would we all use 10KA breakers if your home service could short 20KA?.


Just because the panel can short 10KA among bus bars, chassis, or whatever without melting does not mean you ever want to try it. So you want to keep the current limited using 100 amp or 200 amp breakers or whatever matches the kind of service you installed.

Ability "to short 20 KA" also needs a paragraph of explanation. Is it just theoretical given the resistance of the metal parts inside, or is it related to lightning arresting features?

When you get a tingle touching something that should be grounded, suggesting that a ground was energized, and a huge fault is not occurring, then you have an imperfect ground from that point back to the panel. Older systems including BX that rely on the cable sheath to serve as the ground are likely to have this kind of problem because the sheaths are screwed to junction boxes in the usual daisy chain from receptacle to receptacle. These screw joints oxidize.

If a properly grounded wire or object were to become energized by a branch circuit fault including from a pull-damaged wire in a conduit, that circuit's breaker will trip.

A long (single conductor 14 or smaller gauge) wire that can be stretched from room to room can come in handy. Once you suspect a "ground" is energized, you need another zero volt reference. The official zero volt reference is the panel ground/neutral bus bar. Use your voltmeter to measure from the suspected energized ground down to there*. Turn off breakers one at a time until this "ground to ground voltage" drops to zero. Now you found the circuit that is "energizing the ground".

Sometimes the continuity back to the panel ground is so imperfect that phantom voltages give you a tingling when you touch supposedly grounded equipment plugged in. Then establishing a proper ground back to the panel -- a new bare wire roughly following the route of the branch circuit will work -- will drain off the phantom voltage and not trip any breakers.

For curiosity's sake only. Downstream of the 20 foot melted together conduit wires find a metallic path between plumbing and that circuit's wiring (or the conduit itself) so as to cause the massive fault current in the pipes to choose that conduit as a route back to the panel ground.

* I will leave it as an academic exercise using the volt and ohm functions of a multimeter to find out when and where plumbing fixtures or radiators can be used as a zero volt reference so you don't need such a long wire to stretch all the way down to the panel. Or you can use a radiator anyway and jump to the conclusion you found the circuit that is energizing a suspected ground when you flipped off a breaker and the voltage between the suspected energized ground and the radiator dropped to zero. Do not touch the end of the long wire to things at random with the power on and without going through a voltmeter (not set to ohms). Turn off power before doing any ohms (resistance; impedance) measurements.


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## Gigs (Oct 26, 2008)

AllanJ said:


> Ability "to short 20 KA" also needs a paragraph of explanation. Is it just theoretical given the resistance of the metal parts inside, or is it related to lightning arresting features?


Lightning is irrelevant here. If you have 10 kiloamps of lightning, it's all over.

What we are talking about is the short circuit current of home service.


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## rgsgww (Jul 5, 2008)

Lightning is a whole other story. The strongest of lightning can be 100ka or more. It jumps anywhere it wants and does a "skin effect" of sorts on wiring.

I would not expect a tvss to even be intact after a direct lightning strike.


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## InPhase277 (Feb 9, 2008)

Gigs said:


> Lightning is irrelevant here. If you have 10 kiloamps of lightning, it's all over.
> 
> What we are talking about is the short circuit current of home service.


The series rating is what allows us to use 10 kAIC breakers. As long as the main is capable of interrupting the expected fault current, then we can use breakers downstream from that with a lower AIC. For example, if the main is 22 kAIC, then we should be able to use 10 kAIC breakers.


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## Yoyizit (Jul 11, 2008)

InPhase277 said:


> The series rating is what allows us to use 10 kAIC breakers. As long as the main is capable of interrupting the expected fault current, then we can use breakers downstream from that with a lower AIC. For example, if the main is 22 kAIC, then we should be able to use 10 kAIC breakers.


So can we say with some certainty that the max current available at a resi. panel is <22kA, which implies a xformer impedance of >240/22kA = >11 milliohms?

For a house drawing 200A with a drop of 24v would give an upper limit of ~120 milliohms.

Turns out measuring this impedance with a DVM and a 24A load may be a bit messy.

Anybody have a link for Fusing Philosophy or rationale for resi. wiring that would explain why you can use 10k and 22k?


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## jamiedolan (Sep 2, 2008)

*Electrical Horror Show Part 1*

Enjoy...


More scary "junction boxes" here...


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## jamiedolan (Sep 2, 2008)

More scary junctions. Last one is a milk slot used as a junction box. Is that UL listed??? In the sleeves are junctions between knob and tube wire and thhn. 

Other scary junction boxes shown here were photographed as found without changes.


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## jamiedolan (Sep 2, 2008)

I had to remove a couple wires that were damage... Yea, that was just about all of them.


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## jamiedolan (Sep 2, 2008)

How would you like your THHN, well done or extra crispy?

See that last photo, Yes that is a junction to knob and tube, that was made with electrical tape to romex, than someone buried that in the ceiling and ran the power to the kitchen light.


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## rgsgww (Jul 5, 2008)

I don't think you can trust any wiring in that house! A full blown rewire would sound like a good idea!

I thought I found scary stuff in my basement...

That house is just waiting to go....


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## rgsgww (Jul 5, 2008)

You should post some at electrical-photos.com they would love them there!


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## thegonagle (May 20, 2008)

Oh my! I'm not an expert, but I recognize "way below code" when I see it. That house was a mess in the first place. After that accident, I wouldn't trust one single thing left in there. 

Looks like the whole grounding system took a whole lot of current. The fact that many circuits were ungrounded, and the fact that the main was off, may have saved the house from burning down. Your folks are very lucky.


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## Ultrarunner2017 (Oct 1, 2008)

rgsgww said:


> I don't think you can trust any wiring in that house! A full blown rewire would sound like a good idea!
> 
> I thought I found scary stuff in my basement...
> 
> That house is just waiting to go....


I agree. This would be a perfect time for a total rewire. Best advice I can give here is to check all of your smoke detectors immediately, and add as many as you need to bring the whole house up to spec.
I would shut off all breakers that are not absolutely necessary, and only keep them on during the day, when you're home. Perhaps installing some AFCI would be in order.


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## Ultrarunner2017 (Oct 1, 2008)

Jamie;
I was shocked when I first started reading this thread; I recalled your thread a few days ago on the subject of Copper & Aluminum. You were discussing the situation in your dad's panel.

I am so happy for you and your dad that nobody was injured.
I am curious as to whether or not either of you had considered having POCO cut the power to your panel prior to doing this work. 
I know that if I had to work with large (grounded) cables in my panel, I would not want to work on a live panel.
I have installed/removed plenty of circuit breakers in the live panel, but the smaller wires are so much easier to manipulate, and keep out of the way of the live parts.


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## jamiedolan (Sep 2, 2008)

KE2KB said:


> I agree. This would be a perfect time for a total rewire. Best advice I can give here is to check all of your smoke detectors immediately, and add as many as you need to bring the whole house up to spec.
> I would shut off all breakers that are not absolutely necessary, and only keep them on during the day, when you're home. Perhaps installing some AFCI would be in order.


Despite the electrician saying it was fine to have the breakers on (he said the ac was ok too, that was the melted thhn shown in the photos) I turned them off. My dad and I put in some new romex and did about 10 strands of THHN. Only new stuff is running. Well there are 2 piece of romex between 3 outlets that I have energized (now on a GFCI), We were able to physically see some of the wire and the connections and there was no sign of damage. So that is the only thing that is old that is energized. Also that wiring we run somewhat recently and we knew it was not cross connected in some burried junction box or anything else weird. But other than that, everyhing else else old is deenergized. I think there are several circuits that share a neutral (and no it is not a properly setup mwbc). 

I'd like to see it all be new wiring by the time where done, and will hopefully come very close to that. 

That kitchen floor is 4 inches of concrete. With a Hilte, we were able to drill and fish right through it up into the wall, went well.


Jamie


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## jamiedolan (Sep 2, 2008)

KE2KB said:


> Jamie;
> I was shocked when I first started reading this thread; I recalled your thread a few days ago on the subject of Copper & Aluminum. You were discussing the situation in your dad's panel.
> 
> I am so happy for you and your dad that nobody was injured.
> ...


Yes, it was something I was considering. I had no idea my dad was going to try and work on that cable himself. If I were to move that live, I would have made sure that it was done in a fashion that was safe, including wearing PPE. (I had my full face welding shield and jacket in mind.)...

Jamie


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## Leah Frances (Jan 13, 2008)

School me if this is a hijack. But, I've gotten a little nervous about my theoretical knowledge after reading this thread - I too have a house full of sub-standard wiring that I am in the process of fixing.

If I turn off my Main Breaker (the big one at the top labeled 200Amps this kills power to all my other breakers, right? I assume, however, there still must be somethings in front of the Main Breaker that are still 'live'. 

Bottom line, how to I keep from making the same kind of DIYer mistake that OP's Dad made?

Leah - I check my smoke detectors weekly and I'm current on my homeowners - Frances


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## jamiedolan (Sep 2, 2008)

thegonagle said:


> Oh my! I'm not an expert, but I recognize "way below code" when I see it. That house was a mess in the first place. After that accident, I wouldn't trust one single thing left in there.
> 
> Looks like the whole grounding system took a whole lot of current. The fact that many circuits were ungrounded, and the fact that the main was off, may have saved the house from burning down. Your folks are very lucky.


Yes, I agree, after I saw that THHN mess I pulled from the AC conduit, I realized that there may very well be more melted wires in the walls.

The electrician that was suppose to come today called and said they have never done any meggering in a residential setting and they were not sure they could produce accurate results. 

We are now aiming more towards a complete rewire to be on the safe side. Considering the messes I have started to find, the buried junction boxes, etc. I am sure it is the best decision. My dad got so fed up today, he was saying we will just knock holes here and there and etc etc.. I am like NO I can fish it.... Give me a few minutes...

Anyone know how to plaster?:no:

Jamie


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## jamiedolan (Sep 2, 2008)

Leah Frances said:


> School me if this is a hijack. But, I've gotten a little nervous about my theoretical knowledge after reading this thread - I too have a house full of sub-standard wiring that I am in the process of fixing.
> 
> If I turn off my Main Breaker (the big one at the top labeled 200Amps this kills power to all my other breakers, right? I assume, however, there still must be somethings in front of the Main Breaker that are still 'live'.
> 
> ...


Off means your breakers are off and the buss bar after the main is de-energized. However the service entrance cable that feeds into your main breaker is still energized. This is normally unfused service and is very dangers, as you can see from the "demonstration". I've been warning people about unfused service for a while after reading of some people on here that had near-misses and they didn't have any idea how dangerous what they were doing was.

Any contact with the service entrance cables (if the insulation is worn down enough so you can contact the cables, which it often is on the old se cables) or with the main lugs that clamp down onto the service entrance cables is very dangerous. just draging wires that are bare or even the ends of insulated wires over these service entrance cables is a very bad idea.

Jamie


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## Yoyizit (Jul 11, 2008)

jamiedolan said:


> I had to remove a couple wires that were damage... Yea, that was just about all of them.


Pick your insulation material, find ignition temp., compare with that of wood.
http://www.tcforensic.com.au/docs/article10.html


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## thegonagle (May 20, 2008)

Maybe you can get that electrician who all but refused to do the megger test to work with the insurance adjuster in order for them to see that the house has "an extremely high probability of an _electrical fire loss_ in the future" and "because of this accident," every circuit in the house must be replaced. :yes: In a perfect world...

Best of luck for you and your parents,

your neighbor to the west (and a couple degrees north, not that it matters; we both live in beautiful states).


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## Leah Frances (Jan 13, 2008)

Maybe it's the insomnia talking but... why don't people shield the service entrance cables? I know that's what insulation is supposed to do, but wouldn't a simple non-conductive barrier offer some protection? 

Don't worry, I'm not going to start installing cut up soda bottles into my panel, but if this situation harbors such potential danger, shouldn't there be something we can do about it?


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## rgsgww (Jul 5, 2008)

Leah Frances said:


> Maybe it's the insomnia talking but... why don't people shield the service entrance cables? I know that's what insulation is supposed to do, but wouldn't a simple non-conductive barrier offer some protection?
> 
> Don't worry, I'm not going to start installing cut up soda bottles into my panel, but if this situation harbors such potential danger, shouldn't there be something we can do about it?



Ive seen pictures of Federal Pioneer breaker panels that do have an enclosure inside the panel for the SE. They are in Canada though.

My Square D QO main breaker has lugs with plastic barriers on the side (So I never touch the lugs), I could put a temporary piece of duct tape over the face of the lugs when I work.

Watch out when the AC is on...don't want to bump that.


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## AllanJ (Nov 24, 2007)

>>> How do I keep from making ...

Have a little paranoia. Connect the #4 wire to the panel before clamping it to the water pipe. (Or unclamp it from the water pipe before disconnecting it up in the panel.)

I now suspect that the OP's father was trying to disconnect the #4 ground wire from the panel and it slipped and touched the live service terminal nearby.

Measure the voltage between the #4 wire and the place you are going to connect it to before making the connection.


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## hastime (Feb 12, 2009)

*Megger Test*

Hello, You seem to know about megging circuits. I have an Amprobe 45 digital meggar and I have to meg a house that was hit with high voltage. a 4800 volt utility line came down and hit the messenger line to the home. Several wires burned up and of course it melted the electrical panel. I want to meg the branch circuit wiring in the home that I cant see behind the walls and ceilings. I know I have to perform the meg test but I am a little unsure on how to actually use the megger correctly.

I know I have to disconnect everything in the house and turn on light switches and remove bulbs. Do I disconnect all of the grounds and neutrals from the panel and then connect the leads to hot-neutral, than neutral-ground, then hot-ground wire. Do I then send 1000 volts setting on meggar through the wiring. I am lost at what a good ohm reading should be. Can you help me figure this out?

Thanks


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## jerryh3 (Dec 10, 2007)

hastime said:


> Hello, You seem to know about megging circuits. I have an Amprobe 45 digital meggar and I have to meg a house that was hit with high voltage. a 4800 volt utility line came down and hit the messenger line to the home. Several wires burned up and of course it melted the electrical panel. I want to meg the branch circuit wiring in the home that I cant see behind the walls and ceilings. I know I have to perform the meg test but I am a little unsure on how to actually use the megger correctly.
> 
> I know I have to disconnect everything in the house and turn on light switches and remove bulbs. Do I disconnect all of the grounds and neutrals from the panel and then connect the leads to hot-neutral, than neutral-ground, then hot-ground wire. Do I then send 1000 volts setting on meggar through the wiring. I am lost at what a good ohm reading should be. Can you help me figure this out?
> 
> Thanks


If you don't know how to use it, why would you be using in someone's house?


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## hastime (Feb 12, 2009)

*Meggar*

I know how to use it but am unsure what the readings should be, it is not in milliamps but OHMS. Everybody has a different opinion on the correct way to test the integrity of the romex. I was looking for an explanation to make sure I do it correctly.


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## Scuba_Dave (Jan 16, 2009)

WOW, glad no-one was hurt
I use a rubber pad across the main lugs when I'm in the panel
Covers them completely, I was thinking it was just being overcautious
Now I know its a good thing


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