480 volt 1/2 hp motors

[eesonny]

I am having difficulty sizing the fused feeder for starting 8- 480 volt 1/2 hp motors (FLA .9 amps. 1 size 1 starter for all motors) with nameplate indicating 6 amps inrush. I have sized a 15 amp fused feeder. Is that correct?

 

[jumper]

Kinda hard to help without seeing your math and reasoning behind the "15A feeder".

 

[petersonra]

all of them are on a single starter? presumably separate overloads though.

take a look at 430.53 (A) and see if it applies to you.

 

[eesonny]

One size 1 starter for all the motors and each have internal overload protection.

 

[jumper]

One size 1 starter for all the motors and each have internal overload protection.

Okay. Do you want help sizing the feeder conductors, feeder OCPD, both......:?

 

[eesonny]

Feeder fuse size....

 

[augie47]

From 430.52 I would think that a 10 amp fuse was more appropriate but, if you meet the criteria spelled out in 430.53, your 15 amp fuse is allowable.

 

[Jraef]

If they all start at the same time, which they will if there is only one starter, then it's a 4HP motor for all intents and purposes. You can't run any smaller than 14ga wire anyway, so protecting the individual motor leads is not an issue here; your feeder conductors going TO the starter will be the same size as the conductors going FROM the starter to all of the motors. You are already covered for the individual motor overlad protection, so really, this looks like a 4HP motor circuit as far as the fuse is concerned.

 

[eesonny]

Thank you guys....