Sizing a disconnect. please help.

[rjgordon223]

Here is my issue.I am installing a new rack of compressors in a factory. I am using pre-existingequipment. My rack has a max over current rating of 500amps but the very expensivebreaker (GE spectra high break 1200 amp frame) only goes down to 600 amps. I waswondering if I could install a 600amp fused disconnect with 500 amp fusesbetween the rack and the breaker. Would this be legal?

 

[conmgt]

I would say absolutely. Imagine if you had to install a disconnect next to the compressors because of the breaker being too far away. That disconnect can be fused and as long as the disconnect is rated same as the breaker feeding it, all good. Putting in lower amp fuses is only a problem if they aren't the correct style for the disconnect and the right type for your application. That's my thought.

 

[augie47]

A 600 amp fused disconnect with 500 amp fuses looks like it would fit the requirement fro your rack.
How are you supplying the line side of the disconnect ?

 

[chris kennedy]

How are you supplying the line side of the disconnect ?

My guess is with a pile of electrons.

 

[rjgordon223]

great! thanks a bunch. this route is about 3000 cheeper!

 

[chris kennedy]

great! thanks a bunch. this route is about 3000 cheeper!

There is a member here that I got a reconditioned and tested spectra from. Not going to mention what I payed, but we call him Zog.

 

[rjgordon223]

My guess is with a pile of electrons.

lol a whole lot of electrons. 600x1000000000000x1000000000000x sec x square inch....or a 600 amp breaker.

 

[rjgordon223]

A 600 amp fused disconnect with 500 amp fuses looks like it would fit the requirement fro your rack.
How are you supplying the line side of the disconnect ?

a 600 amp breaker...GE spectra highbreak