Electrical help

tedinatl

tedinatl

Joined
Nov 1, 2010
Messages
893
Hi guys,

I've recently wired my shop for 240V, but I had a question on the size of the breaker. First-off, the 240V line is on a completely separate panel (previous owner had this wired for a hot tub, I believe), which is a good thing. It is a smaller panel with only three breakers in it - one 120V 20A breaker and two 240V breakers - one 30A and one 20A. I hooked up the new 240V outlet to the 30A breaker. So my question is, are these breakers enough for running a 2HP DC motor (Baldor CD6202 - 2HP 180V 1750rpm) with a speed control (KBPC-240D), or do I need to put a 50A breaker in there? The motor I have isn't working, so I can't test it (waiting for a new one).

Thanks in advance!
 
Does the plate on the motor have an amperage listed on it? I would think that as long as the breaker has a higher rating than the motor and the wires are of the proper size you should be OK. (Please note, I am not an electrician and I did not sleep in a Holiday Inn last night. If you have any doubts, contact a qualified and licensed electrician. The cost of one more than out weighs burning your house down.)

Bruceter
 
Im not an electrician but in Australia and we have 230v as standard. Does the motor list its watt usage? If so just divide that by 180v and youll have your max amperage rating. Generally electrical devices here will use a max of 10amps at 230volts and 2300watts so I think you are safe with the breaker as long as the correctly rated wire has been used to carry that max current or you may cause a fire.
From the motor specs you listed Im sure the motor will be fine, should be well under 10amp.
 
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As already mentioned, 30 amps 240 should be more than enough to power that drive and motor. I'd be surprised if 20 wasn't enough.

BTW, this is an application where the motor power isn't the entire story. There is a big bridge rectifier and filter capacitors in there too.

I would like to point out, the breaker is sized to the wiring, not the load. If you have ten gauge wire, you can have a 20 amp breaker. If (hypothetically speaking) you end up needing a 50 amp breaker, you can't just swap it in, you would need properly sized wire first. Probably #6. A large breaker on small wire is how fires get started. A small breaker on large wire won't hurt anything, but is not normally done.
 
Just to reinforce what was said, you'll be fine with a 30 A breaker. As long as the wiring is large enough to handle the current, you will have very little risk of a fire hazard. 2 HP is a fairly strong motor but if you end up bogging it down somehow, worst case the stall current will just trip the breaker and you'll have to reset it
 
I'm a local 24 IBEW journeyman wireman...Nathan the Machinist is right...you should be fine with the 30A breaker, as long as your wire is the right gauge. 12ga=20A, 10ga=30A, 8ga=40A, 6ga=50A I know NEC code books state the wire is rated for less (12ga=15A...etc) but 10ga wire will handle 30A. If you're planning on running the grinder all day, I would go up a wire size to keep resistance low and reduce heat (ie 8ga instead of 10ga) you can always make your wire bigger without a problem...it becomes a problem when people try to keep costs down and use wire thats too small. hope this helps.
Chris
 
Thanks for the info, guys. Confirming what I thought.

FWIW, the entire circuit is wired with 6 guage wire. I don't want to risk electrical fires!
 
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