I have a friend who just moved into her mother's house (her mother passed away earlier this year). The home was built back in the 1940's and is a bit lacking in terms of electrical for today's world. I swapped out some old broken two prong plugs for newer three prongs so she could plug some of her newer appliances in, which prompted me to wonder about swapping some GFCI's in on the circuits for the kitchen and two bathrooms to add a bit more protection.

So here's my question. The house is only wired with a hot (black) and common (white) wire (i.e. no ground). Are there any issues or tricks installing GFCI's in this environment?

I think you could install a GFI breaker for those circuits.

The outlets that were installed already need to be swapped for GFIs. In the box there will be a sticker that says no ground present, and that should be applied to the outlets. Alternatively as was posted above a GFI breaker could be used as well.

There is nothing special for hooking up with out a ground. The ground is not needed for a GFI to function. The GFI reads power on hot and neutral and trips if that difference is ever not zero.

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Originally posted by bigdeal:
I swapped out some old broken two prong plugs for newer three prongs so she could plug some of her newer appliances in, ...

The house is only wired with a hot (black) and common (white) wire (i.e. no ground).

Unless you confirmed the boxes in which those outlets you installed are grounded, you violated code and, more importantly, created electrocution hazards everywhere you did that.

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Originally posted by Skins2881:
The outlets that were installed already need to be swapped for GFIs.

Clarification: By this he means the outlets you switched to three-prong already.

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Originally posted by Skins2881:
Alternatively as was posted above a GFI breaker could be used as well.

The outlets still need to be labelled "No ground present," no?

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Originally posted by ensigmatic:

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Originally posted by Skins2881:
Alternatively as was posted above a GFI breaker could be used as well.

The outlets still need to be labelled "No ground present," no?

Anytime a three prong outlet is installed with no ground it is to be labeled 'no ground present' no matter if you are using device or breaker type GFI.

If the house was built in the 40's, I assume it's wired using metal-case BX wire?
Doesn't the metal covering act as the ground, and you just attach the green ground wire to the metal electrical box?
I'm obviously not an electrician, but that's what I was told.

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There is nothing special for hooking up with out a ground. The ground is not needed for a GFI to function. The GFI reads power on hot and neutral and trips if that difference is ever not zero.

Close . The spec for tripping is 4-6 milliamps of current difference between hot and neutral . This is supposed to be below the threshold for causing cardiac issues .

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Originally posted by selogic:

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There is nothing special for hooking up with out a ground. The ground is not needed for a GFI to function. The GFI reads power on hot and neutral and trips if that difference is ever not zero.

Close . The spec for tripping is 4-6 milliamps of current difference between hot and neutral . This is supposed to be below the threshold for causing cardiac issues .

No need for that kind of detail for this discussion, but close. Depending on the year of manufacture will determine the milliamp rating of the GFI.

It is considered perfectly acceptable to convert two-prong receptacles to GFCI and is actually a good idea to do so.

Simply replacing a two-prong receptacle with a three-prong receptacle when there is only a neutral and hot wire and no ground wire is NOT ACCEPTABLE and against code and is a dangerous practice.

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Originally posted by Skins2881:

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Originally posted by ensigmatic:

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Originally posted by Skins2881:
Alternatively as was posted above a GFI breaker could be used as well.

The outlets still need to be labelled "No ground present," no?

Anytime a three prong outlet is installed with no ground it is to be labeled 'no ground present' no matter if you are using device or breaker type GFI.

Question. By installing a few three prong outlets in the existing wiring setup (i.e. without a ground wire), did I create a risk that didn't already exist with the two prong outlets? I'm starting to think GFCI breakers installed in the main box might be a better idea to trying to cover all the outlets in the house as opposed to me installing a few GFCI outlets (assuming of course I can find some breakers that will work in that old box).

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Originally posted by bigdeal:
By installing a few three prong outlets in the existing wiring setup (i.e. without a ground wire), did I create a risk that didn't already exist with the two prong outlets?

Yes you did. Any appliance with a three prong plug will have a cabinet ground. Anything with a motor and a two prong plug will be double insulated. Therefore, you have allowed a three-prong appliance to be placed in service without a proper ground.

Have you tested for a ground? The boxes may be grounded.

I am over time changing over to the circuit Breaker style.

Over time the outlets seem to go bad.

I am guessing the contractor grade the builder put in are crap.

I have not had any problem with breaker style

Here's the ugly truth - the house needs to be completely rewired.

Hating commence.

I've remodeled a early 30's bungalow and had that done as a college electrical class project, I don't recommend that route. And it wasn't inspected by the teacher who wasn't even present some days. There were few issues but I had to completely redo the entrance to power company specs.

I'm currently (!!) working on my (potentially) last home with smaller projects and updating. Ran a new pool circuit in conduit with external GFCI's, bathroom etc. The outside one attracts ants which blow them, I'm getting 20 months life out of them and replaced 6 already. That circuit will go breaker next. Bath was an addon to an existing and it's been fine for 5 years.

The previous home, the 30's bungalow, was originally a 10 fuze box, likely an upgrade for the stick fuzes used with knob and tubing still in use. No ground, fabric covering, runs thru joists with ceramics. Push button light switches and a screw in receptacle in the LR. Oh yeah!

Just no. Unlike upholstering basement dens, a rewire will pay on resale as the new owners won't be forced to do it, and the house approaching code that exists for the last twenty years is considered a much better buy. She may likely have a 60 amp supply when a house now in the same footage would start with a 200. She's not likley loading it up - anyone reading this who moved in would be extremely frustrated with the antique power system.

Imagine having one outlet in your garage. I do. My fantasy garage will likely have a box as big as the house. It's just more realistic and code. I watched a TOH chicken coop build and they had more power in it than my 30's house.

Changing out receptacles is a "nice to do" thing for mom, a complete renovation of the wiring is a mandatory thing that will happen sooner or later. If you plan to rent after she's gone - I'm 68, the '30s house was surrounded by seniors passing way - and half became rentals. Ours was - that renter will stress your electrical. And as my son in city .Gov has confirmed, most older homes 50 years or more are the source of most of the fire calls.

You don't want to contribute to that with a substandard dwelling that adds to the insurance load in your community when it goes poof.

If you can DIY start with a complete new entrance and then do the major appliance wiring, kitchen, bath, and others in descending load order. Or, have it bid and ouch. Mom, you, the neighborhood, and the city all benefit. One less fire call is a thing.

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I've remodeled a early 30's bungalow and had that done as a college electrical class project, I don't recommend that route.

No shit. I mean, I wouldn't trust the students at the barber college to give me a haircut... And a bad haircut won't result in my house burning down.

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So here's my question. The house is only wired with a hot (black) and common (white) wire (i.e. no ground). Are there any issues or tricks installing GFCI's in this environment?

This old house covers changing over plugs/receptacles/GFCI, nice write up on how to do it.

El Linkamundo

Can You Install a Three-Prong Outlet Without Ground Wires?
Old-fashioned two-prong receptacles, also known as outlets, connected to two-wire cables don't have the ground wires that protect people and electrical devices in case of a fault. Yet it is possible to retrofit a new three-prong or GFCI receptacle into the same outlet box without any rewiring, as long as the box itself is grounded.

Luckily, metal boxes attached to armored, or BX, cable—a type of wiring commonly found in old houses—generally are grounded; the cable's flexible metal jacket serves the same purpose as a dedicated ground wire.

Outlet Versus Receptacle: What’s the Difference?
Outlet—Anything that has a power current taken out and utilized. For example, appliance outlets, smoke detector outlets, and lighting outlets.
Receptacle—Is an outlet. A contact device is installed at the outlet for the attachment of an attachment plug.
Why Install GFCI?
Even if an outlet box isn’t grounded, installing a GFCI in it will still protect you (and your tools and appliances) from ground faults.

But an ungrounded GFCI can’t safeguard sensitive electronics, such as a computer or phone, from the interference caused by stray currents. The National Electrical Code requires you to stick a label on the receptacle that reads, “No equipment ground.” These labels come in the box with a new GFCI.

How to Replace Two-Prong Outlets to Three:
Follow the steps below to learn how to ground an outlet.

Step 1: Check for ground
Insert one prong of a circuit tester into the receptacle's hot slot (the shorter one), and touch the other to a screw that secures the cover plate.
The tester should light up. If it does not, the box is not ­grounded. You can install a GFCI (see steps below), or call an electrician to fix the wiring.
Step 2: Remove the old receptacle
Turn off the power at the ­breaker panel or fuse box.
Unscrew the old receptacle from the box and detach the wires.
Step 3: Connect the new receptacle
Attach the black (hot) wire to the brass terminal and the white (neutral) wire to the silver. On a GFCI, use the terminals in line with the "line" label on the back of the receptacle. (If your box is not grounded, skip to Step 6.)
Step 4: Fasten the ground screw
This green screw, sold in hardware stores, fits in a threaded hole in the back of the box.
Hook one end of an 8-inch green grounding wire or pigtail (also available at hardware stores) to the screw and tighten it.
Step 5: Ground the receptacle
Secure the other end of the 8-inch grounding pigtail to the green grounding terminal on the three-prong or GFCI receptacle.
Insert the new receptacle into the box.
Step 6: Turn on the power
Use a circuit tester to make sure the circuit is working.
Steps for Installing a GFCI Outlet
Turn off the power to the receptacle. Use a voltage tester to confirm.
Remove the cover plate with a screwdriver.
Disconnect the receptacle from the electrical box using a screwdriver.
Loosen the wires on the hot and neutral sides of the outlet. If the power isn’t shut off, the screws are where you’ll be shocked.
Remove the outlet.
Before installing the GFCI, make sure there is enough room in the old outlet box. If the GFCI is too big, you’ll need to purchase and install a larger box.
Repeat the process in reverse with the GFCI receptacle.
Resources
A room will have to be rewired if there isn’t a ground present. However, if you want to have a grounded, three-prong receptacle without rewiring, you can also use a ground fault circuit interrupter (GFCI) found at any home center.

Shopping List
GFCI outlet
Cover plate

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Originally posted by Skins2881:

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Originally posted by selogic:

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There is nothing special for hooking up with out a ground. The ground is not needed for a GFI to function. The GFI reads power on hot and neutral and trips if that difference is ever not zero.

Close . The spec for tripping is 4-6 milliamps of current difference between hot and neutral . This is supposed to be below the threshold for causing cardiac issues .

No need for that kind of detail for this discussion, but close. Depending on the year of manufacture will determine the milliamp rating of the GFI.

Can you tell me where you found that information ? It's been 4-6 Ma for years .

It appears I was wrong, couldn't find anything with a quick Google search. I thought my electrical school teacher said that older GFIs were 20ma, but it appears I was wrong or confusing it with old pool light GFIs or one's not designed for 15/20a 120v circuits.

Either way this is a little think in the woods for this discussion.

Sometimes, and more times in older homes, the outlet box is too small to accommodate the larger GFCI receptacle. It just won't fit. You can remove the old box and install a new one or you can adapt to a surface mount box that the device will fit into.

If you install the GFCI receptacle as the first one in the daisy-chained-fed receptacle circuit, you may leave or even install the normal 3-prong grounded receptacles in the rest that follow the GFCI protected one. Be sure to connect the incoming feed to the "line" marked terminals and the outgoing wires to the "load" marked terminals.
You will still need to use the "no ground present" stickers on the receptacles too.

A GFCI circuit breaker in the panel can do the same as the above paragraph and you won't need a GFCI receptacle at all because the breaker will provide the GFCI protection that the GFCI receptacle would have otherwise provided.

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Originally posted by yanici:
Sometimes, and more times in older homes, the outlet box is too small to accommodate the larger GFCI receptacle. It just won't fit.

Yep, that is usually the case. However, HD sells a shallow mount Leviton GFCI that gets good reviews.

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A GFCI circuit breaker in the panel can do the same as the above paragraph and you won't need a GFCI receptacle at all because the breaker will provide the GFCI protection that the GFCI receptacle would have otherwise provided.

That's what I'm thinking is the better solution, again, assuming I can find breakers that will work in her old box.

To those suggesting a complete re-wire, though that might be the 'best' solution, she who owns the house doesn't have anywhere close to the coin currently to contract that job. I'm simply trying to help her out where I can.

There's another issue - GFCI is going away for Arc Fault.

As usual, they are slightly higher. https://ask-the-electrician.co...0-12-afci-arc-fault/

The long term issue is that meeting code is a moving target, and the longer a home owner waits, the more extensive the rewire and costs.