Understanding the electricity in my new house

Old 11-10-04, 04:12 PM
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Understanding the electricity in my new house

Just when I was starting to understand the electricity in the old house, we up and moved. Our buyers were complaining about all the 2-prong outlets we left them... well, good thing they weren't buying my new house! At least in the old house almost all of the two prong outlets were ground-ready (tested grounded to the middle screw on the outlet cover) and only a couple of three-prong outlets were open ground.

So, my current house wiring is sort of confused. House was built in 1929 or 1930. It was upgraded at some point to 100amp service with circuit breakers. Most of the house wiring is the old two black wires with no ground stuff, but there is some three wire cable. A handful of ungrounded three-prong outlets. Two were also reverse polarity, which is easy to fix. There's a ton of two-prong outlets... I think they may be ceramic, with the T-shaped polarized plugs. I'd like to upgrade these, but I'm assuming they're all ancient 2-wire cable, and just swapping in 3-prongs won't ground them.

One 3-prong receptacle was grounded by accident. There was three wire cable coming into the box. The black and white wires were attached properly to the receptacle, but the bare grounding wire was wrapped "out of the way" around the other two and tucked out of sight under the metal clamp holding it to the back of the electrical box. Why would someone do that? Another one actually had two sets of wires, one the old two wire kind and one the three wire kind, and again the grounding wire was wrapped around the other two. Since in that one it wasn't actually touching any metal part of the box, the outlet was open ground.

And now that I've found out that you guys hate the back-stabbed wire conections, I probably have to go back and fix the three receptacles I wired that way. I thought it was so cool, to not have to bend the wires. Oh, well, back to struggling with the screws.

So with the old wires, is there no good way to fix an open ground? I saw something about using a GFCI, but most of the outlets I've peeked into have only one set of wires. I haven't checked them all, but so far I've only seen the one that had line and load, so there doesn't seem to be any "down the line" to protect that way. And wouldn't the GFCI need that grounding wire? And should I be putting them in in the kitchen? There's two main sets of outlets (four grounded outlets and one or two switches in each bank) at countertop, two separate circuits. One is on a circuit all by itself, (but no, my fridge isn't on that one, since it didn't fit in the space there, long story) and the other shares with a bunch of other rooms and includes the switch for the garbage disposal.

I have a basic working knowledge of receptacles and switches, mostly gleaned from the books Black & Decker Home Repair 2000 and Home Depot's Wiring 1-2-3 and reading X-10 wiring diagrams. I stick to the simple jobs like rewiring existing receptacles and switches, and replacing existing fixtures.

So any chance I can get these outlets upgraded/grounded on my own?

Old 11-10-04, 05:16 PM
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With the amount of effort required to add a Code compliant grounding method to 75 year old wirng you are better off to run new wiring with a ground built into the cable. This would also be a good time to update the wiring and circuits to todays standards.

GFI's do not need a ground wire to function. The internal circuit measures the outgoing current vs the returning current. If an imbalance is sensed the GFI will stop the flow. The TEST button will work on an ungrounded GFI, but a 3 light tester for GFI's will not trip the GFI. The tester diverts the hot side to the ground pin.
Old 11-11-04, 07:16 AM
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Lastly, if you like the 'back stab' receptacles, but actually want some quality, then you should get 'specification grate back wire' receptacles. These are more expensive than standard receptacles, but you get something quite sturdy for your money. You push the wire into a hole in the back of the receptacle, and then tighten down the screw. A pressure plate clamps the wire, giving a much better connection than the cheap-o back stabs.


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