Should I use a two-pole contactor on a single-phase 240V motor?

[htroberts]

I also asked this question on mikeholt.com, but I wanted to see what HVAC-talk thinks.

I was asked recently why I was using a two-pole contactor to control a 1Ø 240V motor (versus a marginally cheaper single-pole contactor).

Not using a two-pole contactor feels wrong to me, and from a safety perspective I don't want to not switch any ungrounded conductors--that's the same to me as switching a neutral in a hot-to-neutral circuit.

Is this (not switching all ungrounded conductors) a bad idea?

[mechanical'al]

Yes I'm with you on that though it is comonly done anywhere to save a dime

[ga-hvac-tech]

Something to think about:

Any time we alter the factory design (regardless of what anyone thinks, or what the facts are), we put ourselves in a position of liability.

If the factory built the unit with a single pole contactor, then to change it to a two pole (regardless of safety) will place the tech at liability for safety; because the UL certification has been altered.

Yeah, that does not make a lick of sense... however when one is in a courtroom common sense is not the issue... whatever the law dictates IS the issue.

If we can get rid of the lawyers... then we can operate common sense again... (not holding my breath).

[mechanical'al]

yes that's a fine point there ga-tech dont want to marry any-thing

[syndicated]

Aren't the single pole contractors used when the mfg is too cheap to put a real crank case heater in, and uses one compressor winding for that purpose?

[carmon]

man...... put a 2 pole contactor in.... no liability issues in Canada..... single pole is just wrong in my opinion....

[rich pickering]

man...... put a 2 pole contactor in.... no liability issues in Canada..... single pole is just wrong in my opinion....

Since when is there no liability?