GFCI Breaker Install

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Old 04-12-18, 12:02 PM
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GFCI Breaker Install

On one of our new rentals, they previously put 3 prong outlets in. But it tests ungrounded--and there's only 2 wires in the box.

So I thought I understood, that one of the methods to remedy this was to put a GFCI breaker in. The installation instructions however reads: "install gfci breakers only on grounded power circuits."

So now it seems I can't do it. Can someone elaborate? Is this something new? I prefer the GFCI breaker over other methods.
 
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Old 04-12-18, 01:56 PM
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I'm not sure why that instruction would be included -- certainly it applies for new installs, but in retrofit you absolutely can put GFCI breakers or receptacles on ungrounded circuits. It is one of the methods that the code allows for remediation of the safety hazard presented by ungrounded circuits. I assume the manufacturer's instructions are for new installations.

You also are supposed to put "GFCI Protected Outlet" and "No Equipment Ground" stickers on the three-prong receptacle face plates. The breaker usually comes with a sheet of labels for that purpose.
 
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Old 04-12-18, 08:53 PM
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OK so then it being a retrrofit, is there really any problem proceeding with a GFCI breaker?
 
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Old 04-13-18, 03:49 AM
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As mentioned installing a GFCI receptacle or breaker on an un-grounded circuit is an accepted method.

Installing a GFCI will only protect from personal injury. It is quite possible that they are attempting to take responsibility/liability away if you have electronics connected to this circuit that is GFCI protected as there will not be a ground; thus placing a sticker stating "No Equipment Ground".

Also note that although using a GFCI receptacle or breaker on this circuit is acceptable using a "tester" to trip the GFCI receptacle or breaker will not work. This does not mean that the GFCI is not functioning correctly. The tester will only trip if the circuit is grounded. To test a GFCI circuit that is not grounded you must use the "test" button on the receptacle or breaker and then press the "reset" after testing it.
 

Last edited by AFJES; 04-13-18 at 03:53 AM. Reason: Add "tester" explanation
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Old 04-13-18, 04:11 AM
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I also want to point out here that just because you have 2 wires in an outlet doesnt mean there is no ground in that circuit. There are two scenarios that I have seen frequently:

- There could be a ground wire (bare copper) and the ground screw could be on top of the outlet box which you cannot see unless you cut the wall out completely.
- The two wires could be running inside a BX metal armored jacket/conduit which acts as a ground which also grounds the box.

These two scenarios were common in my house built in a time period where there were no 3 prong outlets yet the box was grounded. You need to use a multi meter and check the voltage between a hot source (any source is fine, I tend to use an extension cord’s hot prong) and the metal box in question.

Every single one of my electrical boxes in my house, over 30 of them in total, were grounded like this. I have never ran into a metal box that wasnt grounded.
 
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Old 04-13-18, 05:17 AM
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the two wires could be running inside a BX metal armored jacket/conduit which acts as a ground which also grounds the box
But if old style BX with no bonding strip it may not be an adequate ground.

There could be a ground wire (bare copper) and the ground screw could be on top of the outlet box which you cannot see unless you cut the wall out completely.
But can be seen in the breaker box as a bunch of bare #16 copper wires. Also a check with a multimeter is required to verify they are connected.
 
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Old 04-13-18, 11:08 AM
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Originally Posted by ray2047 View Post
But if old style BX with no bonding strip it may not be an adequate ground.

But can be seen in the breaker box as a bunch of bare #16 copper wires. Also a check with a multimeter is required to verify they are connected.
Yes you are right. In my case, hot to ground (metal box) always measured 118.9-119.9V which I think is ok.
 
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Old 04-13-18, 12:28 PM
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The following is my opinion only. I would test under load not just a meter. To test under load I would use a pigtail lamp holder with a 100 watt incandescent light bulb. Touch the leads to hot and the box. If the bulb lights at full brightness I'd be more confident it might act as a low resistance ground.
 
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Old 04-13-18, 03:47 PM
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Originally Posted by ray2047 View Post
The following is my opinion only. I would test under load not just a meter. To test under load I would use a pigtail lamp holder with a 100 watt incandescent light bulb. Touch the leads to hot and the box. If the bulb lights at full brightness I'd be more confident it might act as a low resistance ground.
I like that idea. Do they sell those in that form or do you have to DIY them? If latter, whats the ideal components to use?
 
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Old 04-13-18, 05:12 PM
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They come that way from the factory. Example: https://www.homedepot.com/p/LEVITON-...-000/100356874
 
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Old 04-13-18, 06:32 PM
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Originally Posted by ray2047 View Post
They come that way from the factory. Example: https://www.homedepot.com/p/LEVITON-...-000/100356874
Thanks Ray, I will get one of these
 
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Old 04-13-18, 08:27 PM
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Well as it turns out we got one GFCI breaker installed on one circuit. For the second circuit needing GFCI protecting--couldn't do it because that circuit was sharing a neutral with another circuit. Can someone explain why the install won't work in that case?

So we solved it by just installing GFCI outlets
 
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Old 04-14-18, 05:36 AM
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A GFCI tests for imbalance on the neutral. If the difference between the amperage going out on the hot and returning back on the neutral is more than 4 to 6 miliamps the GFCI says "nope, not happening" and trips. If a GFCI breaker is placed on a circuit that has a shared neutral there will be an imbalance of in and out therefore it will trip the GFCI breakers.

Sharing a neutral from another circuit is not a good practice and actually should never be done even if not using a GFCI. It is very possible to overload a neutral and that is something you don't want to do.
 
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Old 04-14-18, 06:03 AM
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Properly done a multiwire branch circuit is safe and used everyday without incident. The service to your house is a multiwire circuit . The neutral will not be overloaded. Multiwire circuits save time and materials.

The afci requirements will cut down on the use of multiwire circuits due to the shared neutral issue and the lack of two pole afci breakers.
 
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Old 04-14-18, 08:00 AM
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OK great...one more question. If theoretically I needed 2 circuits GFCI protected--neither with shared neutrals--is there a way to use a 2 pole GFCI breaker to accommodate them both?
 
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Old 04-14-18, 09:16 AM
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The 2 pole breaker would only have a terminal for one neutral . You need 2 single pole breakers or just use gfi devices.
 
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Old 04-14-18, 08:16 PM
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Interesting thanks! Which leads to more things to understand...such as--if the 2 pole breaker has only one neutral terminal, again theoretically why can't you just wire nut the 2 sp neutrals to one lead and put it on that terminal?

What are 2 pole GFCI breakers generally used for?
 
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Old 04-14-18, 08:39 PM
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A 2 pole gfi breaker is typically used for a 120/240 or straight 240 volt circuit. A hot tub would be one application .
 
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Old 04-14-18, 08:40 PM
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What are 2 pole GFCI breakers generally used for?
240 volt applications such as a Spa.
 
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