Receptacle with two hot wires and no neutral

Question

I have a location in my house where I would like to install a standard 120V grounded receptacle. Currently there is a blank wall plate.

It is connected to a 2-pole 20A breaker which is labeled "heating" but appears not to actually be connected to anything other than this junction box… including any of our baseboard electrical heaters.*

When I open it up and remove the screw-on wire nuts, I find a single conduit containing:

• White wire (12 AWG solid)
• Black wire (12 AWG solid)
• Bare wire screwed to the frame

The wiring visually appears to be identical to other locations in the house where grounded 120V receptacles are connected…

… but when I measure the AC voltages between these with a multimeter, I find:

• Bare-to-black: 120V
• Bare-to-white: 120V
• Black-to-white: about 211V

As I understand it, these voltages indicate that the white and black wires are the legs of a single-phase 208V circuit:

• 208V single phase and 208V 3-phase
• 208 circuit with no neutral

Here are my questions:

1. Does it make sense that there is no neutral wire in this junction box?
2. Is there any way to safely wire a 120V receptacle here without touching the circuit breaker?
3. If not, is this page correct that the breaker needs to be replaced in order to safely wire a 120V receptacle?

   1. 120V Single Phase power wiring
      1. Install a 1 Pole Circuit Breaker (CB)
      2. Connect (1) 120V 1 Phase power wire to the 1 Pole CB
      3. Connect (1) Neutral wire to the Neutral Bar

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* House is in western Canada, built in the 1970s. It has been remodeled a couple of times, and there might have been a baseboard heater connected here in the past. Many of the circuit breaker labels had been scratched out and rewritten, or were just wrong, when we moved in.

Answer 1

As I like to say, neutral is always white, but white is not always neutral. You have correctly identified that white here is a hot wire and not a neutral wire, which is 100% perfectly fine on a 208V/240V circuit, as long as no neutral is needed. That is normal for a baseboard heater, and occasionally is used for other things such as a cooktop, though most 208V/240V residential circuits in the US/Canada fall into one of two categories:

• Larger than 20A - typically water heater, HVAC equipment, vehicle charging (EVSE). In fact, many of these can be 20A, particularly EVSE, but it depends on the specific equipment and other factors.
• 3-wire - i.e., with neutral - typically clothes dryer, oven - and also a Multi-Wire Branch Circuit (MWBC). In these circuits, white goes back to being neutral and the hots are black and red.

A white used as anything other than neutral should be marked with black or red (or any color except green or white) tape to indicate it is not neutral, but the installers probably figured "it is a 240V circuit, so nobody will get confused".

In any case, making this particular cable suitable for 120V usage is very simple:

• Disconnect the white wire from the breaker
• Install the white wire on the neutral bar

That's it. You do NOT have to replace the double-breaker with a single breaker. You can replace it, but if you do then you have to fill the other space with either another breaker or a filler plate. If you want to add another circuit for some other purpose then go ahead and replace the breaker now. If not, leave the double breaker in place and save $10 - $20 (price varies depending on brand and where you buy your breakers).

Answer 2

Functionally, yes, you could simply move the white wire from the two-pole breaker to the neutral bus bar and then you would have a 120V feed that could be used for a 120V receptacle (assuming the breaker really doesn't feed anything else).

Legally, maybe not. Nearly all 120V receptacles require arc-fault (AFCI) protection under the latest versions of the CEC and NEC. The installation is not "grandfathered" since you did not have a 120V receptacle there before. Generally, AFCI protection is done at the circuit breaker (it can be done in a junction box-mounted receptacle if all the wire from the panel to the box is in conduit or equivalent).

There's also a good chance of needing GFCI, but that's easy to do at the receptacle.