# Did I wire my outlet backwards? Does it even matter?



## Code05 (May 24, 2009)

Not to be mean, but you really need someone to teach you the basics before you hurt yourself or someone else.


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## Mathlete (Nov 3, 2011)

Not mean at all. I agree. 
But, how about an answer to the above?
Socket works fine, and I replaced it exactly as it was.
Does it matter if the wires are flipped, in terms of which side they are attached to?
I don't see that it matters. The wires form an open circuit, and the electrical plug closes it.
Does it matter which "side" the hot is coming from? No, b/c I can plug something in upside down, and it still works.


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## Code05 (May 24, 2009)

Start here.

http://www.allaboutcircuits.com/


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## joed (Mar 13, 2005)

First of all you can't replace two prong receptacles with three prong when no ground is present.
Proper wiring of a receptacle is the black(hot) wire on the gold screw. I don't know if that is left or right. It depends on how you hold the receptacle.
White wire goes on the silver screw.
Ground wire goes on the green screw.


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## Billy_Bob (Sep 11, 2008)

Things are usually the way the are for a reason...

Electrical outlets have a larger opening on the neutral (white wire) side and a smaller opening on the hot (black wire) side.

That is for a reason.

If you touch the hot side, you will get shocked.

Some appliances and table lamps have a "polarized plug", that has a larger prong on the neutral side. You can only plug that in one way. In the case of a lamp, this connects the ring of the socket to the neutral and the center connection to the hot.

You can accidentally touch the metal ring of a light bulb when changing it. If it is connected to the hot, you may be electrocuted and could die.

Or someone else in your family changing the light bulb could be electrocuted.

Or someone who buys your house 50 years from now.


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## Speedy Petey (Feb 1, 2004)

Mathlete said:


> Not mean at all. I agree.
> But, how about an answer to the above?
> Socket works fine, and I replaced it exactly as it was.
> Does it matter if the wires are flipped, in terms of which side they are attached to?
> ...


YES, it matters. Many things are polarized and having the hot and neutral in the right place keeps things safe. As in the illustration above. 

Also, a multi-meter is NOT a safe or effective way to check to see if your wiring is grounded. You can very easily get a false positive with some kinds of cable. Just because you get continuity to ground does NOT mean the wiring has a safe effective means of equipment ground.


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## Mathlete (Nov 3, 2011)

BillyBob, thanks for that specific scenario of why the order may matter.
I will fix my outlets, but in theory, the current can work either way. It's just a safety issue. Cool to know!

GOLD screws are labelled HOT
SILVER screws are labelled WHITE

How do I safely determine which wire is the HOT? (Black vs. yellow)
Once I do that, I can rewire them to the correct side.

There is no ground wire 
(Yea, I am either going to ground via socket housing, or install GFCI)


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## Mathlete (Nov 3, 2011)

Code05 said:


> Start here.
> 
> http://www.allaboutcircuits.com/


There must be 1000 pages in there. Def. out of scope for a simple grounding project. I'm not looking to change careers or get certified. I''d love to read this encyclopedia when I'm retired.


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## AllanJ (Nov 24, 2007)

Always turn off the breaker for the circuit being tested before using the ohms or continuity function of a multimeter.

The following test can be done to tell you which wire (black or yellow) is hot. Get a long length of 14 gauge wire, enough to run from the breaker panel neutral bus bar (terminal strip) up the stairs and across the floor to the outlet box where you are working. Measure the voltage between the yellow wire and the end of the loose wire you strung. Measure the voltage between the black wire and the end of the loose wire. One meausrement should be about zero and that is the neutral. The other measurement should be about 120 and that is the hot wire.

If the loose wire isn't long enough go down to the basement then you can try attaching the far end to a water pipe or radiator in which case the test results will be an educated guess (not foolproof) as to which wire is hot.

Do not touch the end of the loose wire to other wires in outlet boxes; use the loose end only for multimeter measurements.


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## Billy_Bob (Sep 11, 2008)

The black wire should be the hot wire and the white wire should be the neutral wire. (If the wiring was properly installed.)

And good to see you are learning quickly! Ask plenty of questions and you will learn a lot. I used to go watch electricians at construction sites when I was a kid (and still do as and adult*  ). I learned quite a bit that way...

*Now I mostly just watch major projects. Like replacing an electrical pole or whatever.


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## Billy_Bob (Sep 11, 2008)

Here is a bit more on polarized plugs...
(Power switches in appliances may only disconnect one wire...)

"Polarized plugs and sockets are those designed to connect only in one orientation, so the live and neutral conductors of the outlet are connected (respectively) to the live and neutral poles of the appliance. Polarization is maintained by the shape, size, or position of plug pins and socket holes to ensure that a plug fits only one way into a socket. The switch of the appliance is then connected in series with the live wire. If the neutral wire were interrupted instead, the device would be deactivated but its internal wiring would still remain live. This is a shock hazard; if the energized parts are touched, current travels to earth through the body. Devices that especially present this hazard include toasters and other appliances with exposed heating elements, which with reversed polarity can remain live even when they are cool to the touch."

Above from...
http://en.wikipedia.org/wiki/AC_power_plugs_and_sockets


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## jimmy21 (Jul 2, 2008)

Mathlete said:


> BillyBob, thanks for that specific scenario of why the order may matter.
> I will fix my outlets, but in theory, the current can work either way. It's just a safety issue. Cool to know!


Its not just a safety issue. I would go as far as to say that MOST things will work fine with backwards polarity. Lightbulbs, hair dryer, toaster, etc. Most things will probably be fine, but are you willing to plug your bran new 60 hd tv in there, because i sure as hell wouldn't. Its a gamble every time you plug something in.


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## AllanJ (Nov 24, 2007)

Actually all electronic and electrical equipment will work with a 2 prong plug inserted backwards into the receptacle. In the case of radios and television sets there may be a slight increase in interference from stray electrical fields (you could say phantom voltage radiating into the air) if the plug is inserted backwards.

In modern equipment neither the "hot" nor the "neutral" may be connected to the chassis. Difficulty would be had only if there was a defect inside causing the neutral and the chassis to become bonded and also someone touched an exposed metal part bonded to the chassis or the piece of equipment was connected (say via a coaxial cable) to another piece of equipment whose chassis was grounded.


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## oh'mike (Sep 18, 2009)

Doesn't any body own and electrical tester?

A simple $3.00 tester will tell you a lot----please buy one.


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## brgmgb (Aug 25, 2011)

For a few dollars, you can buy a tester that has three lights. You plug it into the outlet, and the combination of lights will let you know if there is a problem. On the one in the picture below, reversed hot/neutral will light the left two lights.


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## oh'mike (Sep 18, 2009)

I never assume that black is hot and white is neutral---always check with a tester--always.

This is especially important with Romex wiring systems--often the power is carried on the white in a switch leg----

If you don't own a tester--don't mess with the wiring---Grumpy old man!!! (mike)


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## AllanJ (Nov 24, 2007)

In the OP's case, he wired up a 3 prong receptacle unit to a 2 wire system. The impropriety of doing that is a separate topic and has already been touched upon above. The plug in tester with a few tiny lights inside would not give useful results with nothing connected to the green screw of the receptacle and the quality of bonding of the outlet box (if metal) back to the panel ground unknown.


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## Code05 (May 24, 2009)

oh'mike said:


> Doesn't any body own and electrical tester?
> 
> A simple $3.00 tester will tell you a lot----please buy one.


Nope, but I got a Fluke T-2, T-26, T5-600, T-179, and a T-1607. Throw in a Vol-con selenoid tester for phamtom voltage elimination.

Will any of those work?:jester:


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## oh'mike (Sep 18, 2009)

Code05 said:


> Nope, but I got a Fluke T-2, T-26, T5-600, T-179, and a T-1607. Throw in a Vol-con selenoid tester for phamtom voltage elimination.
> 
> Will any of those work?:jester:


Yep! 

Those are so much better than licking two fingers and grabbing the wires!!


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## Snav (Aug 20, 2009)

oh'mike said:


> I never assume that black is hot and white is neutral---always check with a tester--always.
> 
> This is especially important with Romex wiring systems--often the power is carried on the white in a switch leg----
> 
> If you don't own a tester--don't mess with the wiring---Grumpy old man!!! (mike)


Yes - this.

NEVER assume - ALWAYS test!

My house is (well - was) wired officially and completely BACKWARDS. Meaning: the whites were wired 'hot' to the breaker box and so forth.

Ok - so I had to find out the hard way the importance of testing everything and never taking anything for face value.


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## joed (Mar 13, 2005)

oh'mike said:


> I never assume that black is hot and white is neutral---always check with a tester--always.
> 
> This is especially important with Romex wiring systems--often the power is carried on the white in a switch leg----
> 
> If you don't own a tester--don't mess with the wiring---Grumpy old man!!! (mike)


 The black should always go to the gold screw and the white to the silver screw. If the receptacle tests as reversed don't just hook them up backwards. Trace the circuit backwards until you find where they have been reversed.


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## brgmgb (Aug 25, 2011)

AllanJ said:


> In the OP's case, he wired up a 3 prong receptacle unit to a 2 wire system. The impropriety of doing that is a separate topic and has already been touched upon above. The plug in tester with a few tiny lights inside would not give useful results with nothing connected to the green screw of the receptacle and the quality of bonding of the outlet box (if metal) back to the panel ground unknown.


The plug-in tester would show an open ground if there is no ground. Using a similar tester in my house is how I found that two 3-prong outlets lacked a ground wire. 

I agree that a better solution is to test the wires before you hook up the outlet. But on the same vein as the quoted post, the fact that there is a bare copper wire connected to the ground screw in a metal box does not necessarily indicate that that wire connects to anything on the other end.


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## Billy_Bob (Sep 11, 2008)

brgmgb said:


> ...the fact that there is a bare copper wire connected to the ground screw in a metal box does not necessarily indicate that that wire connects to anything on the other end.


 
I once saw an entire addition to an office which had 3 prong grounded outlets and new grounded wiring...

...The only thing was they left the old electrical fuse box and never connected the grounds to anything at the panel! (So none of those grounds worked!)


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## Snav (Aug 20, 2009)

LOL @ Billy - sounds like me in the attic trying to figure out where random ground wires went to and came from.

Well gee - where from? No where! Where to: no where! There for a fashion statement I guess. :laughing:


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## jimmy21 (Jul 2, 2008)

im so glad i wired the house i live in


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## Mathlete (Nov 3, 2011)

I figured out that BLACK is HOT. (And yes, it is incorrectly wired into WHITE on the socket)
When I touch the red probe to the BLACK wire, and black probe to the housing, I get 50 volts.
When I touch the red probe to the WHITE wire, and black probe to the housing, I get nothing.
I will reverse the wires this weekend.

Can I use the housing as a ground, with only 50 volts reading?
Or should I just get a GFCI outlet?


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## Billy_Bob (Sep 11, 2008)

Mathlete said:


> Can I use the housing as a ground, with only 50 volts reading?
> Or should I just get a GFCI outlet?


No. Not a good ground.

Either 2 prong outlet or GFCI and labeled on the cover plate: "No Equipment Ground". Those labels should come with the GFCI.

Note: A GFCI or regular outlet which is not grounded will NOT protect electronic devices from electrical surges. i.e. Surge protector power strips will not work properly in an ungrounded outlet.


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## Mathlete (Nov 3, 2011)

Billy_Bob said:


> Note: A GFCI or regular outlet which is not grounded will NOT protect electronic devices from electrical surges. i.e. Surge protector power strips will not work properly in an ungrounded outlet.


So, what's the recourse for wanting to protect devices with a surge protector in an ungrounded apt? This whole thing started because of that, actually. I just bought a 4000 joule protector for $25. Should I at least try grounding to the 50volt housing, as it's better than nothing, if you're saying GFCI is useless for surge protection.


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