#6 on 60 amp

[RETRAINDAILY]

I've got 2 pieces of equipment data sheet says 35 amp load, 50 amp OCD installed.
I've ran a 1 1/4 for 6 #6 + ECG
Now the plant has 2 60 amp 35k breakers in inventory they want me to use.

so 6 ccc 120 deg. would I need to up size to a #4

 

[augie47]

In one regard, I don't see a problem but it would depend on the specifics. #6 is normally o.k. for a 65 amp load, and if you need to derate 240.4(B) might even help, however, if the manufacturer's instructions call for a maximum OCP of 50 amps, you can not exceed that.

 

[RETRAINDAILY]

the equipment has 50 amp OCD in it, through the door disconnect. fused
it only has 35 amp load

After derating I come up with 49.2 amp for a #6

I can get 7 #4 in the 1 1/4 (table c.8 )so I have no problem up sizing.

I get flustered when I put wire on a breaker that that does not correspond with the breaker.

But I think I 'm good with the #6 the way I understand it.

 

[Dennis Alwon]

#6 is good for 65 amps. If you have 6 CCC in the conduit then you must derate by 80%. That leaves you with 52 amps. 240.4 allows you to use the next standard size breaker as long as the load is not greater than 52 amps

 

[RETRAINDAILY]

I left out the 120 deg. factor

 

[Dennis Alwon]

I left out the 120 deg. factor

Now your in trouble 52 amps *.75= 39 amps

#4 will just make it

 

[curt swartz]

I left out the 120 deg. factor

I'm curious why you ambient is 120F?

 

[curt swartz]

#6 is good for 65 amps. If you have 6 CCC in the conduit then you must derate by 80%. That leaves you with 52 amps. 240.4 allows you to use the next standard size breaker as long as the load is not greater than 52 amps

If 90C conductors are used the starting ampacity for #6 would be 75 amps. I believe this is how the OP is getting the 49.2 amps.

 

[RETRAINDAILY]

I'm curious why you ambient is 120F?

Arizona gets 122 in the summer no air conditioning and above the ovens it's pretty hot up there. the place is ran 24/6 sometimes 7

 

[RETRAINDAILY]

Now your in trouble 52 amps *.75= 39 amps

#4 will just make it

#4 it is It.
probably be a wash wire cost it's 260' and they don't cut #6 at my wholesale house. with a 8 EGC

 

[iwire]

#4 it is It.
probably be a wash wire cost it's 260' and they don't cut #6 at my wholesale house. with a 8 EGC

Have you thought about 250.122(B)?

 

[augie47]

I missed your 120?, I agree with #6 THHN you would end up with 49.2, so 50 would be would max breaker anyway (assuming all 6 are ccc)

 

[RETRAINDAILY]

Thanks for the help