4

Many outlets have a bridge clip on each side of the receptacle. (I have seen these used for things like making one outlet switched on one side but always-on for the other.)

outlook bonding bridge clip

Question: If you have a handle-tied 2-pole breaker, can you cut the hot clip and run one phase to each half of the receptacle? Each outlet would be 120 volts, but the voltage between the hot on each outlet would be 240 volts.

I have heard of people doing this, and it works fine, but does it meet code?

2 Answers 2

12

Yes, that's perfectly legal. The handle-tie (or single-handle two-pole breaker, e.g. QO) is critical - when two different hots go to the same yoke, it must not be possible to shut them off separately.

6
  • Note that this setup only requires the two hots, one neutral, and safety ground, Since the two phases would cancel each other out on the neutral, worst case is that one outlet is supplying full power through to ground and the other is not in use, and that doesn't put any more current through the neutral than a normal setup would. One of the advantages of this setup is that if you ever decide you need a 240V outlet, you can just replace this receptacle with that. Good for workshops where you may upgrade machines from 120 to 240 at some later date.
    – keshlam
    Feb 22, 2023 at 1:47
  • 3
    It's even legal to have both 120V and 240V receptacles on the same MWBC.
    – nobody
    Feb 22, 2023 at 1:54
  • Thanks @nobody -- that's what I guessed, but confirmation helps.
    – keshlam
    Feb 22, 2023 at 2:22
  • @nobody: I think combining 120V and 240V requires the use of a common-trip breaker, however. Otherwise, if one leg were to trip and someone who didn't realize that leg was tripped powered in a high-power 240V heater, devices on the tripped leg could be unexpectedly be powered via the heater. This wouldn't cause overloading of the wires, but having the device start unexpectedly could pose a hazard.
    – supercat
    Feb 22, 2023 at 23:19
  • @supercat that scenario, and a similar scenario with plugged 120V heater and lost neutral, are reasons why MWBC is now banned in my jurisdiction
    – P2000
    Feb 23, 2023 at 7:08
7

Yes, you can do that. However, keep in mind that some of the main uses for MWBCs are:

  • Kitchen - GFCI required for decades.
  • Workshop - GFCI usually required, though depends on a few factors. But unfinished basement, outdoor shed, garage - all now require GFCI.

The problem is that standard GFCI/duplex receptacles do not have that removable tab. In order to GFCI protect an MWBC you have to do one of:

  • GFCI/breaker - readily available for most panels, but generally a lot more expensive than a pair of GFCI/duplex receptacles.
  • Split the MWBC and send each half to a separate GFCI/receptacle. Which if the goal was to get twice the power in the space of a regular duplex receptacle defeats the purpose because now you have to have two of them in a bigger box (or use two separate boxes).

On the other hand, if you want to power 2 servers in a finished room (no GFCI requirement) then this will work just fine.

2
  • 2
    My solution: First box is a duplex to carry the two GFCIs; thereafter, as needed. Actually, I prefer duplex anyway; if I'm going to wire one pair of outlets, two in the same box is not significantly more work.
    – keshlam
    Feb 22, 2023 at 2:23
  • 1
    @keshlam 100% agreed. Catch is that we don't know if OP is a very space constrained situation, though generally those situations are not the ones where you need an MWBC. Feb 22, 2023 at 2:28

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.