Disconnect switch rating

[cppoly]

Can disconnects carry their full rating in continuous load or they do they specifically need to be 100% rated?

 

[herding_cats]

The bigger the better. I routinely run 60A disconnects on 20-30A loads. I would say 125% rated at least. I'm not sure what NEC says about disconnects other than at least 100% rating.

 

[jim dungar]

Can disconnects carry their full rating in continuous load or they do they specifically need to be 100% rated?

I believe they, non-fused ones, are rated and selected like conductors. Once fuses are added they become "80% rated" devices.

 

[herding_cats]

makes sense.

 

[Master Nater]

to an extent, their rating to disconnect would depend upon what they're disconnecting. are you referring to disconnecting a feeder panel or a motor?

 

[herding_cats]

I think he is referring to a motor load from the original post.

 

[infinity]

Motor disconnects are typically sized at a minimum of 115% of the motor FLC.

 

[Master Nater]

ok.

430.110 (A) - Current Rating and Interrupting Capacity - GENERAL - The disconnecting means for motor circuits rated 1000v or less, shall have a current rating not less than 115 percent of the full-load current rating of the motor.
exception - a listed unfused motor circuit switch having a horsepower rating not less than the motor horsepower shall be permitted to have a current rating less than 115 percent of the full load current raing of the motor.

SO, 115% percent of the FLCR, or must have a HP rating printed on it.