disconnect sizing

[AESolutions]

ok here is what i have....its a Carrier pkg unti model 50TM-008-A-601, which is a 480v 3phase, it has two compressors each have a RLA of 6.4 and a LRA of 42, also there are (2) fans which are 1/4 Hp .7 FLA and the IFM FLA is 2.6, it also has heat strips (model#CRHEATER016A00), 13.9 Kw, 16.7 FLA. the table I have for the entire unit says that the MCA should be 24.1 with an overcurrent protection of 25. for disconnect size it says the FLA is 22 and LRA is 108...I'm lost, motors are not my thing, usually pkg have two hookups, this is a single point hookup.

 

[augie47]

This is a case where the manufacturer has done all the work for you.
You simply need to follow their specifications:
the table I have for the entire unit says that the MCA should be 24.1 with an overcurrent protection of 25. for disconnect size it says the FLA is 22 and LRA is 108

Your supply conductor must have an adjusted ampacity of 24.1 amps, and your maximum overcurrent device can not exceed 25 amps.
The standard disconnect size would be 30 amps. (You can check the disconnect specs but the LRA should not be a problem)

You might check and see if there is any limitation shown on the type of OCP.
Fuse, breaker, HACR breaker, etc.

 

[AESolutions]

thanks!!, I think i was just looking into it a bit too much.

 

[AESolutions]

so the feeders to this unit would only be #10? doesnt sound right...it has a single point connection and beyond the connection there are 60a fuses feeding the compressors and another set of fuses (60a) feeding the heat strips, am I missing something? LOL

 

[Cavie]

so the feeders to this unit would only be #10? doesnt sound right...it has a single point connection and beyond the connection there are 60a fuses feeding the compressors and another set of fuses (60a) feeding the heat strips, am I missing something? LOL

I'm bettinig the heat strips are add ons and not figured into the factory name plate.

 

[benaround]

I'm bettinig the heat strips are add ons and not figured into the factory name plate.

It has figured 13.9kw for the heat @ 480v is 16.7amps, With this info I feel the 30a circuit

is all that is needed. See if the 60a fuses have a high AIC on them.