I have a 220v variable speed exhaust fan that I need to buy a speed control for. I always assumed it best practice to use a double pole switch when controlling a 220 motor. Almost all speed controls for 220v fans are single pole and leave the 2nd leg hot. I'm confused why its best practice in one scenario and not the other? Is it worth special ordering a double pole speed control?
220v speed control
- Thread starter tsperry88
- Start date
theoldwizard1
Well-known member
What does a speed controller have to do with a switch ?
nadogail
Well-known member
Have you requested advice from the manufacturer of the fan?
They would be my "Go To".
They would be my "Go To".
220 volts is a line to neutral voltage, & is used in the 50 hertz world, not in North America, but as long as it is not a disconnect is code complaint to only switch one leg of a 208 or 240 volt load, and is a quite common practice on HVAC equipment.
Most speed controls for fans also have a built in switch. Typically single pole. Otherwise you have to have an additional switch to turn the motor off. The manufactures switch is single pole. Its just interesting to me that if I asked about using a single pole switch on a single speed 220 motor I would be advised against it despite being code compliant in many cases. I guess it surprised me that its so hard to find speed controls that are also DPST.
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I hear it referred to as 220 more often than not in the US. What is the correct term? Most motors are stamped 230. Do I say 230 or 240 if 220 is incorrect?
Motors & welding equipment are rated for 115/200/230/265/460/575 volts, supply voltages are 120/208/230/240/277/480/600 volts, 110V & 220V is found in 3rd world countries, if the tag says 230V or even 220V then it would be correct to refer to it as such in my opinion, but the supply voltage is a nominal 240V.
Gotcha. I just assumed people called it 220 as a carry over from days past.
I think I understand the answer to my question, but have a few additional questions. Switching one leg is common and acceptable as a means of control, but not as a disconnect. I believe the breaker is a suitable disconnect, but I vaguely remember it must be in sight of the controlled device? Can a double pole switch be used as a disconnect? When I wired my house 5 years ago, I was told to use a double pole switch to turn off my well pump, but can't remember why.
mike93lx
ALLIANCE MEMBER
A two pole switch will allow disconnecting both hots, so it will kill all power to the unit
I understand, but is it a code approved disconnect? For example could it replace a pull out disconnect on a attic air handler? I know I rabbit trailed my thread....
mike93lx
ALLIANCE MEMBER
Not sure but I personally wouldn't use one to replace something that normally calls for a service disconnect. A pull out disconnect cant be bumped on when someone is working in equipment.
That and pull outs are about 15 bucks, same price as a decent DP switch
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alfredeneuman
Well-known member
Where is 230 generated in North America?
You forgot 347, the Canadian line to neutral voltage of 600V
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Brain fog.Where is 230 generated in North America?
You forgot 347, the Canadian line to neutral voltage of 600V