Three-way switching of 240V load

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charlie b

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Seattle, WA
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I don't know the answer, but I can't think of a reason this would be a no-no, as long as the switches are rated for that voltage. Are you talking about having a wall-mounted receptacle outlet powered by 240 volts with a 3-way arrangement for switching that outlet? Here again, so long as the receptacle is the correct type for that voltage, so that nobody tries to plug in a standard lamp, I think it should be OK.

What is the specific application you have in mind?
 

augie47

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Tennessee
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A normal 3 way is just a SPDT, if you used a DPDT and ran three more wires you could 'three way' switch 240.

Sad to say but I shudder to think of the discombobulation that arrangement would cause with a number of our local "electricains"
 

charlie b

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Can I get back to the original question, and ask why you thought this was a no-no in the first place? What is the application?
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Bob would you draw the switching for the DPDT three-way set up?
Just draw two 120v diagrams, and place one in each conductor.

As Lou pointed out, if you flip one pair of travelers, the light will never come on.
 

gndrod

Senior Member
Location
Ca and Wa
240V 3-way

240V 3-way

Oh, okay. Bob, ignore my last post, please. ;)

Even though running a 240V lighting 3-way is irregular, making a 240V hookup would be no different than a standard 3-way wiring diagram with the exception of the opposite phase leg as a common return to each luminaire lamping rated for a 240V load. There is no grounded neutral return circuit. The travelers switch phase leg A and are isolated from the common phase leg B return in the same 14-3 cable.
 

gndrod

Senior Member
Location
Ca and Wa
14-3 no grounded return

14-3 no grounded return

Just draw two 120v diagrams, and place one in each conductor.

As Lou pointed out, if you flip one pair of travelers, the light will never come on.

Switching one phase on the travelers is proof of the pudding to isolate Phase B as the return in that circuit to the other side of the 2 pole breaker. Not practical for the lighting of modern LED low voltage lamping.
 
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