Changing a switched outlet to half-hot and found pigtails

Question

I’m trying to change a switched outlet to a half-hot outlet. The receptacle itself had one black wire and two white wires (plus ground), and then I saw a pigtail with two black and one white wire.

I broke off the brass bridge tab but then realized that I didn’t have an always hot wire already attached.

Can I just take one of the black wires from the pigtail and add it to the receptacle to make that always-hot one?

Answer 1

Easy one. Here are the secrets:

• The circuit involves a switch loop which uses /2 cable (black-white). Switch loops don't have neutrals.
• If white is not used as a neutral, it must be used for the always-hot, not the switched-hot (so it reliably reads hot when touched with a voltage tester).

So... 1 white among blacks tells us a switch loop is involved, and the bundle is certainly the "Always-Hot bundle".

That being the one you need to add your always-hot pigtail wire to.

All these wires have other jobs to do, and so they must remain together. They are not "spares" for you to pluck one out of. Any end scenario must end with them all still together (plus whatever wire you may want to add).

You'll need to obtain a pigtail wire from any shop that sells wire by-the-foot. Solid white 12 AWG THWN wire (<25 cents a foot) is the universal donor, since it works in 15A and 20A circuits, and can be taped to make it a hot.

DO NOT obtain one by cutting short any of the wires in the box. They don't have length to spare, they have statutory minimum lengths they must have, and you don't have enough excess length to make a pigtail.

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Code now requires that a white wire used as a hot must be taped with black/color electrical tape to indicate its use as a hot, so now is a good time to correct that.

Answer 2

First, you need to be absolutely sure here or poof breaker pop. Do you have a Volt Meter?

You don't have before pictures, do you?

I'm trying to understand the photos you've provided. In the top photo, there are just two wires in the pigtail- right? A pair of black/hot?

Also in the top photo is a pair of blacks and a single white going to another pigtail, which you show in photo 2?

I would be looking for a pair of wires that go out to the switch. That white is a dead give away of a 'runner' for a switch run/return- so one hot out to the switch and back on the white (or in this case, the black!) (should be color coded / sharpied though to make sure).

This is what I think you have- the 2 black pigtail is the switched hot, the return. If you can confirm that the 2-black pigtail goes into the same romex as the white that is tied in with the other 2 blacks (BBW pigtail), then I think it's safe to say that that is a 'hot' and a feeder to additional circuits.

If that previous paragraph is correct, then yes, all you'd need to do is add an additional black off the BBW (making it BBWB) to the single outlet.

It's not nearly as hard as I'm making it but I'm really having trouble tracing the wires from the photo. Best bet is to have the power off and confirm the switch runner pair via continuity, and then (capping the wires to be safe) test which wire coming in is 'hot'.