Motor OCP

[Little Bill]

If you size the amps for a motor from Table 430.248, do you add 125% to what the table says?
Example: 1/2 HP motor, single-phase, 115 (120)V says 9.8A, add 125% = 12.25A
Is this correct?

Specs say motor pulls 4A continuous. But do we have to go by the table if the specs say different?

 

[augie47]

Does the motor nameplate actually say 1/2 HP or is that some other rating such as an air compressor rating where the motor nameplate often is blank on HP ior says SPL

 

[Little Bill]

Does the motor nameplate actually say 1/2 HP or is that some other rating such as an air compressor rating where the motor nameplate often is blank on HP ior says SPL

I haven't seen the motor or nameplate. I was just sent a description, but was told it was specs. It isn't a spec sheet as I first thought. They are sending me that later.
If it helps, the motor is on a fan, it says ball bearing motor and pulls just 4A continuous.

 

[ptonsparky]

I always went by the table.
Something is screwy, double amps doesn't sound right.

 

[augie47]

Sounds like it might well fall into the Exception 2 or 3 of 430.6 in which case you use nameplate.

 

[sparkie1]

430.6(A)(1) has a couple exceptions. The key is that the motor is in a piece of equipment and that you are using the equipment name plate and not the motor name plate. Additionally, if it is a multi speed motor, then you size it differently.

Exception 2 states that you use the FLC marked on the name plate and not the motor HP. So, if that name plate is on a FAN, and that fan's name plate shows the 4A, then you can size it like that. If the name plate is for the MOTOR, then you should use the table.

Either way though, your ampacity is 12A, which means it goes on a 15A circuit. The only difference is whether or not you would need a dedicated circuit for it or if it can be on a 15A branch circuit.

Personally, I would be inclined to think that the name plate is for the entire fan, and then slap it on a 15A or 20A branch circuit and be done. Note that I'm thinking about something like a ceiling fan, a box fan, or one of those fancy shop fans that you mount to move air.

 

[Little Bill]

Here is a pic of the motor and nameplate



image resize service

 

[augie47]

I am still of the opinion the exception applies and you use nameplate but your pic doesn't show HP....did you see a HP rating ??

 

[Little Bill]

I am still of the opinion the exception applies and you use nameplate but your pic doesn't show HP....did you see a HP rating ??

The pic was sent to me. What you see is what I see. Just a description said 1/2 HP.