Ground vs neutral (house)

[Njguy]

Hey guys, whoever wired my house was a moron (old house). The wires are not color coded. I know which wire is live, easy enough to find out with a multi-meter. However I am not sure the best way to distinguish the neutral from ground. As i understand it they are both connected in the circuit box. I was wondering if there was a way to tell with a multi-meter. Thanks again.

 

[RCinFLA]

In the U.S. the normally 'white' neutral wire is connected to an insulated bar within the breaker box. Ground wires are brought back, typically with bare copper if your house is using Romex wire or green if separate wire, to a bus bar that is grounded to the breaker box. (Black is one side of 240v and Red is other side. Neutral is center tap, yielding 120v. You may find red or black wires going to 120v hot lines)

The neutral bus bar (white wires) has a single strap connecting it to the breaker box ground (if box is at service entrance) along with the connection to the outside ground rod. This is NEC code, requiring a single point of ground at the service entrance box.

Even if you temporarily disconnect neutral to ground strap the neutral is also grounded by power company at power pole. You would also have to disconnect main neutral feed from utility entrance.

 

[MikeMl]

This would be a trivial test if you have or can borrow a clamp-on ammeter. The Neutral is a current carrying conductor, while the Ground is not. Any circuit that has a load turned on will show an equal current in the Line and Neutral.

 

[crutschow]

The easiest way is to buy a plug-in receptacle tester that will verify whether the hot, ground, and neutral go to the proper pins.

 

[voidptr]

Here one simple way if every thing is mess up ...
(at less it is easy for me, do that at your own risk !)

get a a roll of speaker wire put a 1k resistor on one lead and 10k on the other lead, shut down main breaker !!! clip the 1k on the ground, and the 10k on the neutral ( if you want you can also do similar things for each phases of 120 with something like 20k and 50k) so roll down the wires at your wall plug and test resistance of each wires it should be easy to untangle wires, mark them...

could be more easy and less dangerous than using a receptacle tester and permuting wires each time...

but use a test receptacle when you finished remounting the wall plug, and test all with live current...

Hey guys, whoever wired my house was a moron (old house). The wires are not color coded. I know which wire is live, easy enough to find out with a multi-meter. However I am not sure the best way to distinguish the neutral from ground. As i understand it they are both connected in the circuit box. I was wondering if there was a way to tell with a multi-meter. Thanks again.

 

[voidptr]

double post ...

 

[KeepItSimpleStupid]

@crutschow

I seriously doubt that the receptacle tester can tell the difference if ground and neutral is switched.

There are some testers (Ideal Sure Test) that can check for neutral bonds in the midddle of a run providing the tester is located > 20' from the real bond. This usually causes GFCI trips, so that kind of tester could help.

A decent electrician would have color coded (taped) the ends of the same colored wires. I can't remember if green can be taoed.

I would think that if te circuit was moved to a GFCI breaker or a GFCI recepacle was used for a test, you could tell if it was wired properly.

Clarification: Hook a GFCI receptacle into an unused circuit in the box. Make a cheater cord with alligator clips and plug into that recepacle. Disconnect a circuit an connect to the GFCI.
Now test,

Meaning:
1. Put a GFCI breaker/recepticle at the box temporarily
2, Put a circuit tracer on the wire and KNOW what the path is.
3, Certain tracers can find wires through the wall.
4. Map out the entire house and its circuits. At least what breaker controls what outlet.

The idea would be to:
1. Place a GFCI breaker or temprarily wire a receptacle at the box.
2. Plug a load into every outlet in that circuit. Idealy, you only need to use the last outlet. The one that doesn't daisy chain to the next.

If the GFCI trips whena load is plugged in, then the neutral or ground are crossed or incorrect somewhere.

Locating the cross, you would plug the load into outlets closer to the box.

So, to really do it right, you need a wiring map.

To guess:
1. Find out which recepacles are controlled by what breaker
2. Find the recepacle with one set of wires. Use that as the test.

You might need more sophisticated tools to find the layout.

In any event, using a temporary GFCI and plugging a load into every outlet on that circuit will tell you if things are wired correctly.

e.g If 3 outlets worked and two didn't, One of the two would be the end, onle likely will have one set of wires and te cross would be at the other one of the two.

Don't forget to include lights.

 

[crutschow]

@crutschow

I seriously doubt that the receptacle tester can tell the difference if ground and neutral is switched.

.........................................

You are correct. They check for other common wiring errors, but not switched neutral and ground.

 

[RCinFLA]

This would be a trivial test if you have or can borrow a clamp-on ammeter. The Neutral is a current carrying conductor, while the Ground is not. Any circuit that has a load turned on will show an equal current in the Line and Neutral.

Change the word Neutral "is' to "should". A Yo-Yo could connect the wide blade (neutral) at AC outlet to the ground connection at breaker box and the ground at the AC outlet to the neutral buss bar. Current carrying would show correct at AC outlet but current would be flowing through ground at box to neutral bond at box. You would also have to check every ground connection at breaker box with a load on the outlets to see if any of the ground connections are carrying current. Matching one particular branch run ground/neutral wiring pair in a wiring rats nest at the breaker box might be quite challenging. If it is using Romex the job is a bit easier.

Sounds like you may have quite a mess to straighten out.

 

[KeepItSimpleStupid]

Yep, as I see it a ground-neutral swap can occur anywhere. So, a GFCI measures the Line-N unbalance. So, you create that LINE-N unbalance with a LOAD. If the load draws the same from N and L1, then the GFCI won't trip. If L and N are switched som where, it will, but the test has to be done at the furtest point and the GFCI has to be located at the service panel.

So, with a map and a GFCI, it's an easy test.

Witout a map, at least find out what's connected to each outlet. Plug a load in each outlet. Turn on all lights associated with that circuit too.

 

[RODALCO]

To prove that the polarity is correct, use an independant Earth tester. Basically a reel of wire on a spike, which gets put in the ground, well clear of water mains and power cables. use a meter or duspol on the other end and test which wires are active and neutral.

A plug in indicator will not show reversed polarity if the Active and neutrals are transposed.