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So I'm wiring up my woodshop and I've got a question about branching a 120 volt circuit off a 240 circuit.

I'm running 12/3 for this circuit coming of a 20 amp 2 pole breaker. The thought for this specific circuit would be for my dust collector and air compressor. Right now both are 120 and I'm just doing a shared neutral with one set of plugs in the box being one circuit and the other being the other circuit. Black and white to 1 set of outlets and red and white to the other.

But I was wondering if I upgrade my dust collector to one that requires 240, could I run the 240 and 120 circuit with that same 12/3? So essentially black and white to the 120 circuit and black and red to the 240?

  • @Steven I see nothing in 210.4 that states they're only allowed within the Kitchen. – flycrg Nov 6 '15 at 17:45
  • As long as all "hot" conductors are rigged to trip together at the panel (they should be, at your double-pole breaker) and you bundle and label both "hots" with the neutral in the panel to indicate the shared neutral situation, you should be good. – Jimmy Fix-it Nov 6 '15 at 17:47
  • @chris This is already coming out of a sub panel. But that sub panel is being fed by 6/3. – flycrg Nov 6 '15 at 18:00
  • Wait, why are you talking about using the neutral (white) on the 220vt dust collector? You need to check the dust collector specs, if it requires a dedicated grounding conductor you are out of luck sharing that with the other circuits. – Jimmy Fix-it Nov 6 '15 at 18:15
  • @Jimmy Fix-it you're right that I wouldn't need the white on the 220. Brain fart. This would be going to either a L6-20 or a 6-20. Also the dust collector right now is 110, I'm thinking for the future since the walls will be closed up if/when that is upgraded – flycrg Nov 6 '15 at 18:24
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The NEC expressly permits 120v & 240v loads on mwbc (multi-wire branch circuit) provided both legs are disconnected at the same time. This point is moot since the same is required for just a 240v circuit.

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