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Anonymous Poster #1

Standard Color Codes for Single Phase 220VAC

01/28/2012 3:14 PM

I'd like to know two things:

1. I'd like to know what the correct colors are for wiring 220VAC appliances in the USA.

2. I'd like to know how to differentiate between Neutral and Ground using a multimeter.

Thanks

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#1

Re: Standard Color Codes for Single Phase 220VAC

01/28/2012 3:42 PM

Black for the two ungrounded conductors, white for the neutral, and green (or bare) for the ground.

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#2

Re: Standard Color Codes for Single Phase 220VAC

01/29/2012 1:25 AM

Greetings.

Actually we have 240vac in the United States. 120vac 1st phase L1 in a breaker panel and 120vac L2 in a breaker panel 180 degrees out of phase with L1. This gives you 240vac between L1 and L2 and 120vac from L1 or L2 to Neutral or Ground.

In a 4 conductor cord of an electric range Black is L1 to black on the back,

Red is L2 to red on the back, White is the Neutral to white on the back,

Green is to the green screw below the Neutral.

In a 3 conductor electric range cord the middle wire is the Neutral and the 2 outside wires are L1 and L2.

For 120 vac appliances the White is the Neutral, the Black is L1 120vac (whether attached to the L1 or L2 bar in the breaker panel) and the green is the case or frame ground.

When wiring a Gas Stove it is important to hook up the frame or case ground because the spark box sends the igniting spark for the surface burners through the surface burner electrodes to frame or case ground to complete the circuit.

The Neutral and the Ground are both grounds. In the breaker panel one goes to the Neutral bar and one goes to the Ground bar.

Hope this helps you.

Have a Great day,

Oly

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#10
In reply to #2

Re: Standard Color Codes for Single Phase 220VAC

01/30/2012 2:35 PM

You know... I sat at my desk debating if I was going to go down this road yet again. Been down it a few times, but, it is so important, that I guess I must.

You said...

Actually we have 240vac in the United States. 120vac 1st phase L1 in a breaker panel and 120vac L2 in a breaker panel 180 degrees out of phase with L1. This gives you 240vac between L1 and L2 and 120vac from L1 or L2 to Neutral or Ground.

This is the great misconception of the standard 120/240 volt consumer service that is in use in North America. The nature of the system being talked about here is as follows...

We have two 120 volt windings that are in phase with each other and that have been connected in series. The center connection between the two windings have come to be known as a "neutral" in North America (though it is not a neutral of any sort and the older name of a "common" is better in my opinion) and as a rule of thumb we ground that connection point though we could just as well ground either end of the series connection and achieve the same thing (though the voltages would be a little off from what we are used to).

The perception of a 180 deg phase shift is only there when we use the neutral as our reference point.

Do the vector math... add one source that is 180 deg out from another source of the same magnitude and the resulting voltage across both sources is 0 volts.

For more reading on this, for anyone interested...

http://www.faqs.org/docs/electric/AC/AC_2.html

This subject needs to be brought up to the educators teaching our trades people as this misconception is very very common. Please do not think this is a "slam" at you in any way or form.

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#3

Re: Standard Color Codes for Single Phase 220VAC

01/29/2012 7:07 AM

2. I'd like to know how to differentiate between Neutral and Ground using a multimeter

Do you want to do that on your appliance (load) wiring or on the supply side?

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#5
In reply to #3

Re: Standard Color Codes for Single Phase 220VAC

01/29/2012 8:58 AM

"Do you want to do that on your appliance (load) wiring or on the supply side"

What's the difference?

But at least your addressing the 2nd question...

As I see it, using a multimeter, can not differentiate between them...

But why do you want to do this?

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#6
In reply to #3

Re: Standard Color Codes for Single Phase 220VAC

01/29/2012 10:25 AM

I was taught that ground should never carry current unless something goes wrong. That tying neutral and ground together creates that possibility if something happens to your neutral.

From a technical standpoint, I know it will work but recall being cautioned that it is a bad practice and has the possibility of electrocution under certain circumstances.

I'd like to identify neutral without having to get into the main box and receptacle and identify it visually.

The previous owner of my house did a lot of wiring himself without benefit of an inspector or common sense. One example of this was finding the clothes dryer grounded to a PVC pipe!

For peace of mind, I want to differentiate neutral from ground on the supply side.

Thanks

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#8
In reply to #6

Re: Standard Color Codes for Single Phase 220VAC

01/29/2012 11:16 PM

You can differentiate between neutral and ground by measuring the voltage between live and each of them.

In practice there is a voltage difference between ground and neutral of less than 10VACrms. Typically around 1 to 4 Volts.

If the reticulation was properly installed then a bonding link (MEN link) would have been installed between G and N at your main box and theoretically the difference should be zero. It seems unlikely that this was done at your premises, given the history, but there may be a (good) legacy predating the previous owner.

You might find that the difference is zero according to your meter. This is unlikely, but if so, connect a lamp across live and each of the other two, in succession, and measure the voltage across the lamp in each instance. There is slightly higher resistance in the earth path than the neutral path and the current being drawn by the lamp will show that by presenting a measured voltage drop.

Summary:

VL-N > VG-N.

If they measure equal load it up with a lamp and measure again.

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#4

Re: Standard Color Codes for Single Phase 220VAC

01/29/2012 8:27 AM

I find this centers on the Code as it is presented to the electrician in many states the 'Neutral and the ground on a 230 Volt circuit are connected to the same lug making the 'white' and the 'green' ground the same electrical connection and the neutral a earth grounded Neutral. In other states it is required that the earth grounded 'green' is separated for safety reasons to ground the equipment base for operator protection. I find this in domestic dryers which have two types of cords and in feeder Boxes where the two are separated, The 230 volt dryer has included a 120 volt motor which will not operate on earth ground. Trailer houses built in the northern part of the U.S. is a good example..

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#7

Re: Standard Color Codes for Single Phase 220VAC

01/29/2012 10:34 AM
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#9

Re: Standard Color Codes for Single Phase 220VAC

01/30/2012 3:38 AM

A2: the neutral will be carrying the imbalance current continuously; the ground/earth will be carrying the fault current only during the fault event before the circuit protection device disconnects it.

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#11

Re: Standard Color Codes for Single Phase 220VAC

01/30/2012 3:56 PM

I've enough information to complete the project I'm working on: a programmable, solid state controller which will manage temperature and soak cycles for a 2500 degree F electric kiln. I'll be firing large glass and ceramic components.

In the interests of sleeping soundly, I will remove the plate from the service entrance and visually inspect the tangle of wires for the CB's with particular emphasis on the supply of power to the paired CB's for the 220VAC outlets.

Then I'll open up the 220 VAC receptacles themselves and see that there is continuity.

You have been a generous group. I appreciate the support.

Thanks. I'm signing off.

Laughing Jaguar.

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#12
In reply to #11

Re: Standard Color Codes for Single Phase 220VAC

01/31/2012 9:23 AM

As you remove the plate, the fun has just begun. If the aparatus has the four wires needed to operate the Green wire must go to earth ground for your safety. regardless of the CB's. For the Circuit coming from the receptical of which you are pluging the wires into or if you are running direct a red and black wire must go to the CB and the white to the neutral lug and the green must go to by its lonesome to an earth ground on it's own. Then you may sleep...

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