Motor Receptacle

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SteveO NE

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So, maybe I am just overthinking/underthinking this problem but I have a 7.5HP 2P 208V motor that needs a receptacle. As I understand it I need a HP rated plug because someone could theoretically use it as a disconnecting means even if there is another disconnecting means present so I will opt to make it the only disconnecting means to not have to double dip on equipment.

So a 7.5HP circuit has a 46A FLA which is 115A calculated breaker size => 125A next size up, conductor only needs to be at 125% of motor so 58A.

Here is the actual question: With a receptacle circuit do I have to size the conductor and receptacle to the OCPD (sized at 250% for inrush and GFP) or do I just size it for the 60A (next size up) receptacle and that is OK because someone would need to put a 60A female plug on a piece of equipment for it to work in this receptacle therefore assume that someone won't put say an 80A motor load on a 60A circuit? If the latter is not plausible and the conductor needs to be upsized, does the receptacle need to be upsized? I feel like someone would already have to go out of their way to install the wrong receptacle on the wrong device so maybe I don't need to upsize everything?

Thanks in advance for your 2 cents.

Steve
 
You always size the circuit conductors per the motor FLA charts in Article 430 based on the nameplate HP and voltage x 1.25, adjusted for voltage drop if necessary. So the basis of your conductor rating must be 46A x 1.25= 57.5A. Assuming flexible cord, that puts you over the limit for #6 (55A) and into #4 cord.

To use a receptacle and cord cap for connecting the motor, they must have the HP rating on them, regardless of the actual current rating. But for 7-1/2HP 208V single phase, there are no NEMA plugs with that rating. Maybe Pin and Sleeve type is available though. In Meltric, which have a HP rating, you have to go to 100A to get more than 5HP at 208V (it jumps from 5HP to 10HP at 208V single phase).
 
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