Thermal Switches

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mshields

Senior Member
Location
Boston, MA
I have a 1HP motor being fed with a 15A, 208V-2P breaker.

Need to specify a thermal switch at the motor. Smallest I can find is 30A-2P. Is that suitable for this motor? My concern is that the overload protection will be oversized.

Also, manual motor starter is same thing as thermal switch right?

Thanks,

Mike
 

david luchini

Moderator
Staff member
Location
Connecticut
Occupation
Engineer
I have a 1HP motor being fed with a 15A, 208V-2P breaker.

Need to specify a thermal switch at the motor. Smallest I can find is 30A-2P. Is that suitable for this motor? My concern is that the overload protection will be oversized.

Also, manual motor starter is same thing as thermal switch right?

Thanks,

Mike

The Square D type F manual starter is rated for up to 1HP single phase. The overload protection is provided by interchangeable thermal units.

I would say that in terms of motors, a manual starter and thermal switch is the same thing. However, thermal switch may refer to something else in a different context.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
The Square D type F manual starter is rated for up to 1HP single phase. The overload protection is provided by interchangeable thermal units.

I would say that in terms of motors, a manual starter and thermal switch is the same thing. However, thermal switch may refer to something else in a different context.
I agree, please define what you mean by "thermal switch". Something like this?
1H385A_lres.jpg

If so, the 20A rating of the switch is just related to the maximum current capability. You still need a thermal sensing device that is inserted into it and selected based on the motor nameplate FLA (Full Load Amps).
 
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