We currently live in a 1953-built house in VA. Both our hall and our living room have inadequate lighting due to the size of the rooms and the positions of the light. We are considering adding lights to the existing circuits, so that, for example, the 2-way hall light switch operates both the current light and a new fixture, and the 1-way living room switch does similar. All the related existing wire is cloth covered copper cable without ground. What would be required to do this according to code? As best I can tell from a Google search, VA is on NEC 2017. We'd probably get an electrician to actually perform the work, but would like to have an idea of the likely scope going in.
Extending an ungrounded circuit is not legal, and that's that.
However, grounding can be retrofit according to rules greatly liberalized in NEC 2014. Under those rules, a ground wire of appropriate size (#14 for 15A circuits; #12 for 20A circuits; #10 for 25-60A circuits) can be run either
- back to the panel the circuit comes from
- to any junction box with a large enough ground back to that panel, even if it's on a different circuit
- to a junction box with non-flex metal conduit back to that panel (though some flex qualifies too)
- to the Grounding Electrode System (bare copper WIRES between main panel and grounding rods or water pipe clamp).
Using water or gas pipe as a substitute for any of the above is forbidden.
However, most likely a pro electrician is going to prescribe replacing all old cable with new Romex. Retrofitting grounds is somewhat easier, but then it leaves the uncertainty of the condition of the old wire, and they don't want liability for that.
I was expecting that to be a likely answer. If we decide to do this ourselves and retrofit the ground, would it be within code to retrofit a ground just to the existing light fixture, then extend from the light fixture using 14/2, or would the ground need to also be retrofit to other parts of the circuit? With the AC in the attic, we could fairly easily pull the ground from the convenience outlet to the light fixtures themselves. Nov 29, 2022 at 22:50
@jgd Yes. This is covered in NEC 250.130(C), you don't need to retrofit grounds to every existing outlet on the circuit. And really, the retrofit ground web doesn't even need to follow the circuit's route, it can just rake across circuits however is convenient. Nov 30, 2022 at 2:17
That's what I was hoping to hear. I'd prefer not to have to deal rewiring the switches in the rock-hard plaster walls. Nov 30, 2022 at 19:23
@jgd I hope you're not trying to tap power from a switch. In a switch/lamp set, only one of them has power and Murphy's Law says it won't be the one you're trying to tap power off of. Switches on switch loops have hot but they don't have neutral, so the hot is useless. Nov 30, 2022 at 22:01
I'm intending to add an additional fixture to an existing switch. My plan would be to retrofit ground to the existing fixture, then run Romex from the hot, neutral, and new ground of that to a second fixture that is controlled by the same switch. My understanding is that in this situation, as long as the same lines go to the same input wires on both fixtures, exactly how the power gets to the switches and fixtures is largely irrelevant. Dec 1, 2022 at 1:42