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Joined: Dec 2014
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Installed a 20-a, 240-v, single-phase, dedicated branch circuit for an automotive lift.
The lift-installation instructions required that the lift-motor supply voltage (under load)and current be measured and recorded.
In doing this, we noticed that the lift-motor control switch is only a single-pole device. Other lifts we have worked on have had 2-pole switches.
We were surprised that a nationally-known, ETL-listed lift would use a single-pole switch on a 240-v device. Our local electrical inspector was also surprised when we informed him of what we found.
I'm wondering what others are seeing in this type application. I don't recall ever seeing a 240-v device operated from a single-pole control.
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Joined: Jul 2004
Posts: 9,677 Likes: 9
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You can use single pole "control" but you still need a 2 pole disconnect. 430.84 Need Not Open All Conductors.
The controller shall not be required to open all conductors to the motor.
Exception: Where the controller serves also as a disconnecting means, it shall open all ungrounded conductors to the motor as provided in 430.111.
Greg Fretwell
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Joined: Sep 2002
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HVAC equipment uses single pole contactors for 208-240V units & 2 pole ones for 3Ø units all the time.
As the code section quoted in the previous post shows, it's quite code compliant, but means any electrician needs to be on their toes & trust nothing.
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Joined: Dec 2014
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Thank you both for your responses.
The circuit in question has of course a 2-pole breaker. The lift was furnished with a pigtail and twist-lock plug, so that serves as the local disconnect.
Most of my experience is in the power industry, and at the utility where I worked, we always used control devices that broke all hot circuit legs.
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Joined: Jul 2004
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Breaking all ungrounded legs is actually pretty uncommon when they use solid state switching for controls.
Greg Fretwell
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Posts: 404
Joined: March 2007
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