Electrical ? motor switch

moresmoke

Well-known Member
Location
E ND
I am working on rewiring my shop. I have most everything figured out, except this. I have an exhaust fan mounted up on the wall. Its an old 120V 1 HP bin fan. What is the proper type of switch to use to turn it on and off? Currently it is just wired with a cord and plug, but I would like to have it hard wired. I am thinking a standard 20A light switch is not the right thing?
 
It'll work, but may not last well . But, ideally you should use a motor rated switch. Most better quality 'normal' switches have a motor rating, but be sure to select one that is high enough.

here's an example:
https://www.grainger.com/product/HUBBELL-WIRING-DEVICE-KELLEMS-Wall-Switch-49YL39?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/49YL39_AS01?$smthumb$
 
With a 1 HP or larger motor, having a "motor starter" or at least a contractor controlled by the switch would be a safer and more reliable alternative, IMHO.
 
CONGRATULATIONS you are right, an ordinary light switch is NOT the right thing.

While sure, an ordinary residential light switch will "work" until its contacts burn, pit or stick from the arcing that occurs when the motor BOTH starts and stops HOWEVER as a retired electrical power distribution design engineer THATS CERTAINLY NOT THE ENGINEERING WAY TO DO IT. When a motor starts it can draw something like in the neighborhood of 4 to 6 times its normal run current PLUS when a motor is shut down and its circuit is broken there's another arc due to the stored energy in an inductor. The better way is to use a motor starter including some sport of thermal overload protection which can be built into the starter (or the motor itself can have such). An alternative, provided the motor has its own built in thermal overload protection, is some sort of sufficient load or HP rated switches or contactors designed to start and stop a motor NOT lights.

Hey I've done worse things lol and I'm NOT saying it wont "work" I'm ONLY saying its best to use a correct designed MOTOR STARTER or contactor or at least a HP and load rated switching device suitable for the motors HP and current (still need thermal overload protection) AS A REGULAR LIGHT SWITCH IS NOTTTTTTTTTTTTTT DESIGNED FOR NOR SUITED TO START AND STOP A MOTOR.

If you visit your local electrical supply house with the motors nameplate data like HP and current and voltage etc they can show you the alternatives from a cheaper manual push motor starter to a magnetic contactor to a starter or even combination starter which has BOTH a disconnect PLUS motor starter and thermal protection. The cheapest alternative can work fine since this isn't an industrial complex and hey Id prob use the cheapest myself lol but just cant advise the use of a regular light switch EVEN IF YES BILLY BOB IT WILL "WORK"

John T too long retired electrical engineer and rusty so no warranty and do whatever you like
 
(quoted from post at 11:43:36 10/10/16) If you go to an electrical supply store they should be able to fix you up with a correct switch. They will need to know amps, volts ext..

They will; and charge like it's made of gold. OP, try Ebay for the motor starter. I've seen them at Grizzly.com for not bullion level pricing too. You need to be a contractor to get a decent price from the supply houses, DIY guys get hosed.
 
An old fused safety switch like used to be used on electric water heaters before breaker boxes became the standard would work and will stand up to the load OK.
 
You need HP and load rated switch or starter suitable for your motor BUT DONT FORGET ABOUT THERMAL OVERLOAD PROTECTION which a starter would have, but just a switch, maybe not?? Of course, the motor may have its own overload protection device in which case you're good to go

Best wishes

John T
 
It may have a red button type push to reset built in thermal overload protector. If so all you need is a switch that's rated to the motors HP and voltage and current IE A LOAD RATED SWITCH versus say a typical cheap residential "Light Switch"

This isn't any super critical or extra hazardous situation, but still Id prefer it be done right if it were mine. Probably the worst outcome is a switch that arcs and burns and sticks, but if it stuck closed that's not any fun thing lol.

John T
 
Yo dr, I bet we have BOTH seen plenty of small motors that have one of those built in red push button reset thermals. No idea if he has that or not. If so a load rated switch to match his motors HP and Voltage will work fine, but you already knew that.

John T
 

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