Help me understand GFCI placement..


Old 04-03-17, 11:43 PM
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Help me understand GFCI placement..

I have an older house, with older wiring in the main section of the house. It's older 2 conductor tinned copper wire.

At some point one of the previous owners replaced most of the 2 prong receptacles, with 3 prong outlets, with no equipment ground hooked up.

There is also an exterior outlet which is a standard 3 prong outlet, that has no equipment ground, but is covered by a silver weatherproof receptacle cover, with one door over each outlet.

So I don't fully understand the correct way to install a GFCI. I've heard if you install a GFCI in one location it can protect the other outlets.

In the pictures below, there is only one cable going to each receptacle. In one picture you have a wire going up to a receptacle in the kitchen, and in the second picture you have the newer white wiring going to the exterior receptacle.

Can I replace these receptacles with GFCI's, and if there is only one wire going directly to the outlet, I don't think it will protect any other receptacles?

The way I understand it, is that if the receptacles are chained together, like in the 3rd picture from a different part of the house, then a GFCI in that location would protect the other 2 receptacles that are downstream from that receptacle.

You can click the pictures below for larger images

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Old 04-04-17, 04:07 AM
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You will need to identify the first receptacle in the run and replace it with a GFCI. Knowing which cable is hot is necessary as it will be placed under the LINE clamps. The cable leaving the box to the other receptacles will be connected under the LOAD clamps. This will give you GFCI protection, but not grounding. It will make the use of the 3 pronged receptacles acceptable. In the GFCI box, there will be two sets of stickers. One will say GFCI protected outlet, and the other will say No Equipment Ground. You will adhere these stickers to the downline receptacle cover plates.

As far as the outside receptacle, if it is not on the same run with the other receptacles, it should be a GFCI receptacle and you must use an "in use" bubble cover, not the metal flap type covers.

1-Gang Extra Duty Non-Metallic While-In-Use Weatherproof Horizontal/Vertical Receptacle Cover with Wasp Guard - Clear-CKPM - The Home Depot
Old 04-04-17, 06:45 AM
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You are correct. Any receptacle at the end of the run cannot provide gfi protection upstream. It would be point of use only.

At other locations with multiple cables you can have point of use or downstream protection .
Old 04-06-17, 08:25 AM
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You may want to "think ahead"... to if a GFCI is installed and protects "downstream outlets"... And you or someone else is using one of those downstream outlets and the GFCI trips off.

Say this is 10 years from now. How will you know where that GFCI is? (So you can reset it.)

That is the problem with using one outlet to protect other downstream outlets. It makes it VERY DIFFICULT to track down and reset the GFCI outlet. Where is it?

Better planning ahead is to use a GFCI breaker. Or install a separate GFCI outlet for every outlet. It costs a bit of money for the latter, but makes it much simpler to reset the tripped GFCI as it is the outlet you are using!
Old 04-06-17, 02:52 PM
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Having GFCI receptacles protecting down stream receptacles on the same circuit is a good practice. It doesn't take a PhD to look at the GFCI in that room to see if it is tripped. You don't have to go all around the house and crawl under it to find the GFCI. "Thinking ahead" would be to localize the GFCI receptacles and save a little money at the same time. GFCI breakers are often more inconvenient as panels are located on different floors, or in garages, so they aren't readily accessible, either.
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