Are thermal overload switches required for single phase motors?

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cppoly

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For single phase motors, are thermal overload switches required at the motor as the disconnect or is a simple on/off toggle switch rated for motors acceptable?
 
cppoly said:
For single phase motors, are thermal overload switches required at the motor as the disconnect or is a simple on/off toggle switch rated for motors acceptable?
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Almost all motors require overload of some type.

The location of the OL is really not dictated but a disconnect switch is required at most motors.
 
iwire said:
Almost all motors require overload of some type.

The location of the OL is really not dictated but a disconnect switch is required at most motors.
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:thumbsup:
(For more detailed information see Art 430 Part III which spells out when OL is not needed and 430.102 for details on disconnect requirements.. there is no "one size fits all rule")
 
I think most the manufacturers list them as "manual motor starters'. They are available from most all your major mfgs; GE, SquareD, Eaton, AB, etc.
(Try 2510 FP Square D)
 
Many years ago, 90%+ of the smaller single phase motors I saw had thermal protection built in. Then, in more recent years, it seems many show up are not thermally protected, primarily in exhaust systems. I don't know if that's due to automated controllers having protection or simply the mechanical suppliers trying to be more competitive.
I would say close to 50% of the exhaust systems I see no do not have motors with thermal.
 
augie47 said:
Many years ago, 90%+ of the smaller single phase motors I saw had thermal protection built in. Then, in more recent years, it seems many show up are not thermally protected, primarily in exhaust systems. I don't know if that's due to automated controllers having protection or simply the mechanical suppliers trying to be more competitive.
I would say close to 50% of the exhaust systems I see no do not have motors with thermal.
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Same here, I see less and less motors with built in OLs.

I am sure it is just the result of building to a price point.
 
electrofelon said:
thats what I was thinking. I thought most single phase motors had it...... maybe not the larger ones like a 5 though?
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I frequently run into 5 to 10 HP single phase motors with internal overload protection - in particular "farm duty" motors often do have it. 90%+ of the time anything under 1.5 HP usually seems to have internal overload protection, maybe 75% or more of the time anything up to 7.5 hp usually has internal protection. Otherwise equipment I typically come across usually already comes with a contactor/overload assembly of some sort if the motor doesn't have internal protection. I often do need an additional disconnecting means if the motor is not going to be within sight of the branch circuit device though.

Also run into several with an internal thermostat that is only pilot duty rated and must be used with a contactor or other remote control device.
 
kwired said:
I frequently run into 5 to 10 HP single phase motors with internal overload protection - in particular "farm duty" motors often do have it. 90%+ of the time anything under 1.5 HP usually seems to have internal overload protection, maybe 75% or more of the time anything up to 7.5 hp usually has internal protection. Otherwise equipment I typically come across usually already comes with a contactor/overload assembly of some sort if the motor doesn't have internal protection. I often do need an additional disconnecting means if the motor is not going to be within sight of the branch circuit device though.

Also run into several with an internal thermostat that is only pilot duty rated and must be used with a contactor or other remote control device.
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Ok good info. Seems you cant really generalize with this.
 
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