I've got a junction box with typical black and white wires, but then there appears to be 2 yellow wires just passing through. The yellow is the hot. I need to tap into this and run over to add a new outlet to my wall. How would I go about this properly? Thanks!

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  • First thing is to find what it powers and if you can add on. Two yellow plus white usually means a 240v circuit and quite a few are only to be used for one device.
    – crip659
    Mar 5, 2022 at 15:42
  • Thanks @crip659! Good tip!
    – guitar4jc
    Mar 5, 2022 at 16:43

2 Answers 2


Since you say yellow is hot and you aren't saying any others are then to me it looks like a junction box in the middle of a 3-way, and the switches are in position for the switched load to be off. The two yellows in the conduit with the white are travelers from a hot fed switch. The conduit with two yellows and black are second switch and switchleg. Flex with black and white are switched fixture (probably a light?).

If I'm right you need to push another wire into the conduit with yellows and white to get to hot the that feeds that switch.

You need to confirm what the wires are feeding, many circuits require dedicated feeds, like kitchen, bathroom, and heating/cooling circuits and some are sized for specific appliance needs.

If yellows are actually a 240v circuit then you need to confirm it's load to verify that the Code doesn't identify it as a load that requires a dedicated circuit, either by load type or size, then read the answer by FreeMan.

  • If those yellow wires are travelers, @harper will be delighted to know that someone followed Harper's Rule.
    – JACK
    Mar 5, 2022 at 19:12
  • Not critical to the answer but for clarity I suspect that the conduit to the second switch has a neutral because it probably feeds through another j-box that feeds additional fixtures on the switch. Mar 5, 2022 at 20:14
  • @JACK I work in buildings where Brown, Orange, Yellow, and Gray are designated as 277/480v to satisfy 210.5(C), so I like to use purples or pinks for travelers. BOYG for 120v just makes me shudder. Mar 5, 2022 at 20:54
  • I've worked in places that tried to designate wire color usage but someone would always come along and screw it up.... would never rely on any of that. I've seen 1-1/2" rigid going into a gutter with every wire color there is and from there going to all 120V equipment.
    – JACK
    Mar 5, 2022 at 23:18

Specifically answering the question:

If you want the new outlet on one of the yellow circuits, is there enough slack somewhere in the yellow wire to pull 12" into this box?

If so

  • Pull the slack into the box
  • cut the wire roughly in the middle, leaving about 6" at each end,
  • wire in your new piece of wire and run it through conduit to the new outlet location.
  • additionally, pull a new white, neutral wire to the new outlet location and wire nut it to the bundle of whites in this box.

Many other things to consider:

When run in conduit, yellow is a perfectly acceptable and normal color for a hot wire. Notice, too, how you have no green or bare wires? That's because the metal conduit & box are your ground.

Those yellow wires are hot because they're attached to a different circuit and the breakers they're attached to are still on. Are you 100% certain that you want the new outlet on one the yellow circuits? If so, which circuit? Since the black wires are already terminated in this box, it would be very easy to tap into that circuit to add a new wire for a new outlet if you can put a random new outlet on that circuit (kitchen outlets must be dedicated to the kitchen).

Things to consider:

  • Where will this new outlet be?
  • Are you prepared to connect new conduit to this box or another one to run to the new outlet location?
  • If you want the new outlet on one of the yellow circuits, is there enough slack somewhere in the yellow wire to pull 12" into this box?
    • By code, each cut end of the yellow wire needs to be about 6" long so there is plenty of working room to make the splice in this box.
  • It might be more fun to watch, but turning off the power before cutting usually safer.
    – crip659
    Mar 5, 2022 at 16:06
  • Excellent info! Thank you!
    – guitar4jc
    Mar 5, 2022 at 16:43
  • 1
    Using one leg of a 240v circuit will create a MWBC (MultiWire Branch Circuit), you will need to group and identify the new neutral with the yellows at each junction box, and make sure they're fed by a common trip breaker. Mar 5, 2022 at 17:45
  • @guitar4jc Be sure to follow NoSparksPlease's advice in the comment above and look at his answer. If this is a 3-way switch circuit, my suggestion won't necessarily work.
    – FreeMan
    Mar 5, 2022 at 19:23

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