We are making settlement on a very nice, solid, big but also VINTAGE home next week, built in 1951.

The VA wanted to see GFI's in the kitchen, bathrooms, basement and outside receptacle which I took care of along with some other things. Since this is an estate sale, I went in and did this on my own dime and time.

My question is about the 2-prong receptacles all over the house: in doing the GFI's for the kitchen I found that every receptacle box was metal and grounded with the ground wire screwed to the box and enough loose to pigtail to for the GFI's and I also went ahead and changed out the wall receptacles downstream of the one counter GFI they were wired in series to to modern 3-prong grounded type receptacles. Every receptacle changed out got a 14 gauge ground wire pigtail.

The issue is that the wiring is a very early 12-2 Romex type where the black and white wires are 12 gauge but the ground wire is maybe a 16 or 18 gauge? Is that enough ground wire to really be safe? I had planned to work my way from room to room and update the receptacles to the modern grounded 3-prong type and tie into the box ground with a pigtail but wasn't sure if I should be looking instead at fishing new wire someday and not using the existing old Romex?

I know you can put GFI's where there is no ground wire and label in "No Equipment Ground" but these boxes are very small and tight for GFI's and the cost is a factor too at $15 a pop vs $2-$3 for a decent regular old receptacle.

What size is the breaker? If these are 15 amp circuits, or you make them 15 amp circuits, the 14 awg wire is sufficient. Assuming it's in good shape and wired properly otherwise.

I am not an electrician.

I wouldn't install GFCI outlets in regular residential areas (bedrooms, livingroom, etc).

That old NM or NMC cable may or may not be in good shape. At the box, where you'll work with it, you may find that the insulation just cracks away. If that's the case, you'll need to replace it. Depending on your local codes / AHJ, you may have to replace it all anyway once you open walls or anything that would require permits.

I've seen enough questionable or even outright failing NM from that time period to think that the best option is to plan for a complete rewire.

quote:

Originally posted by striker1:
I wouldn't install GFCI outlets in regular residential areas (bedrooms, livingroom, etc).

That old NM or NMC cable may or may not be in good shape. At the box, where you'll work with it, you may find that the insulation just cracks away. If that's the case, you'll need to replace it. Depending on your local codes / AHJ, you may have to replace it all anyway once you open walls or anything that would require permits.

I've seen enough questionable or even outright failing NM from that time period to think that the best option is to plan for a complete rewire.

This can be the case, but the vast majority of the time it is not. This is more likely with AC/BX cable with cloth sheathing. By the fifties the insulation in most cases is good to go. You should already know by now with the outlets you have changed if you have crumbling/splitting insulation on the wires.

To answer the original question, you are fine with the reduced size grounds. They serve no other purpose other than to trip breaker if there is a fault. They do not carry any current. I worry more about manipulating the thin wiring and breaking the grounds off. First I would verify with a voltage tester that the metal boxes are in fact grounded, then check and make sure there is more than one or two twists on the ground connections, maybe even add a wire nut. You can install self grounding receptacles in lieu of pigtails to the outlet. I'd prefer this for a non electrician over the pigtails to avoid damage to ground wires, for me I either pigtail or tap a 10-32 hole in box (if not already present) and use a ground screw and scrap wire to ground outlet.

Jesse, since you do this for a living, do you recommend a megger test on the older NM stuff? Do you find it necessary at all? Just curious.

quote:

Originally posted by striker1:
Jesse, since you do this for a living, do you recommend a megger test on the older NM stuff? Do you find it necessary at all? Just curious.

Megging residential wiring is not common. First off you need to disconnect everything, GFIs, Timers, Dimmers, Equipment, Appliances, etc. All of those can be ruined by the voltage. Usually it's only used for out buildings and exterior lighting. I can't imagine anyone doing it for testing purposes, maybe troubleshooting. I've actually never done it inside a house.

The wiring in the walls is always fine. The only places you get problems usually is at devices or fixtures where the wiring has been exposed to air and heat. Those can be visually inspected for cracks, crumbling, and splits. Often time if insulation intact only electrical tape is needed.

I have actually only recommended completely rewiring a few times. Of course one was my mom's house, rewired the whole thing with walls in place (attic and crawlspace). Took an entire summer one weekend at a time, that summer sucked. Work til 5, drive til midnight Friday, work all Saturday, half Sunday, drive home, go to work for the week, repeat. She needed full new service from pole to meter to disconnect, to panel, to all new branch circuits. It freaking sucked.

quote:

Originally posted by Skins2881:
for me I either pigtail or tap a 10-32 hole in box (if not already present) and use a ground screw and scrap wire to ground outlet.

Would it be acceptable to drill a hole in the box then use a sheet metal screw to attach this to the box then the other end to the ground screw on receptacle?

No. Needs to be 10-32 threaded.

Pig tails similar to what you have pictured.

Drill tap that will as name implies both drills hole and cuts 10-32 threads.

Check a box or two first it may already have tapped holes. Either way the drill tap is an awesome tool to own for stripped threads in many applications. Just don't use in anything above 1/8" thick.