GFI Missing Ground Wire
by Tom Thumb
Hey Joe, I've got a quick electrical question for you.
How can I change my old kitchen sockets to GFI protected ones, when they don't already have a ground?
Answer by Joe Trometer
A quick note for everyone: GFI stands for Ground Fault Interrupter on a plug receptacle that is designed to trip and turn off the power to that outlet to protect against electrical shock hazards used near water and exterior locations.
Right, the GFI won't work correctly without the ground wire... Before tearing out the walls and re-wiring the circuit there are 2 things I would check for.
1) Does the existing wiring contain a ground wire that isn't connected or cut off inside the box? Can that wire be loosened inside the box and gently pulled to access that existing but hidden ground wire?
Just this week with a house I'm remodeling that was built in 1953, there were ground wires twisted in the back of the outlet-box that were not connected to the plugs or switches. There's an easy fix for that...
...Turn off the electrical breaker to that plug, gently pull the wires out of the electrical box to access the bare copper ground wires, add an eight inch #12 or #14 bare copper to the existing ground wire with a wire nut, then neatly push the wires back into the handy-box leaving the new ground wire exposed to connect to the GFI grounding screw.
In the case of older homes built in the 1920's that I'm used to rehabbing, there is definitely no ground wire with the old style knob and tube wiring.
2) Is there access to add a single ground wire?
Adding a single ground wire is not the easy choice if there is insulation inside the wall you are working on. If there is no insulation in that wall and you have access to that top or bottom wall plate (stud), here's what I would try...
...Again, turn off the power to that wire while working on it. Drill a hole next to the existing wire where it enters the wall cavity at the basement or attic locations.
Use an electrical Fish Tape or in many cases I use a very small looped chain about eight feet long that will drop into the hole and land where I can grab it with a piece of wire or coat-hanger with a small hook bent at the end.
Inside the electrical receptacle box, open one of the unused knock-outs, feed the small chain to the bottom plate, and try to hook it with that coat-hanger hook. Same with the attic location; drop the chain and try to hook it from inside the handy-box.
One more thing before tearing out the wall...
Cut out a small piece of drywall or plaster at the top or bottom of the wall no larger than your hand to reach inside the wall cavity to make access easier; the small hole is easier and faster to repair than knocking out the entire length of the drywall or plaster.
Add the Number 12 or 14 Grounding Wire
If you were able to get the chain or Fish-Tape from the electrical handy box to the basement or attic, connect and pull a #12 or #14 bare wire into to box.
Connecting the Ground Wire
In the basement, the grounding wire can be connected to the copper or galvanized water pipe for grounding. Be sure to check the water pipe at the water meter for a #6 wire jumper across the water meter for grounding.
PVC or the new PEX water lines cannot be used as a grounding path. If the water lines are plastic, the new grounding wire will have to be run to the electrical panel and anchored to the grounding bar.
If access for the new ground wire was made from the attic, and there is no metal ground to connect to in the attic, a grounding wire could be run through the attic to the exterior and hidden behind the trim of the siding to the electrical service panel or by adding an eight foot grounding rod into the ground.
Note: Exterior Grounding Wire should be #6 bare copper.
After all that, in my opinion, for me, it's probably faster and easier to run a new 12-2 romex cable...
Kill the power to the receptacle, cut out the old handy-box with a reciprocating saw, cut out an access hole at the top or bottom of that wall in line with the receptacle, remove the existing wire to access the original hole in the wall plate (stud), run the new #12 romex wiring, use an old work handy box to replace the old box you cut out, and install the new GFI.
Caution: Due to the hazardous nature of electrical work, I must recommend hiring a licensed electrician for your safety.
The cost of one circuit could be less than $200.00 and save you an entire day’s work if you haven't done this type of work before.
Hope this helps you some,
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