3 phase wiring and #4 ga and proper emt size

[ozeke]

I am running A 3 phase sub panel box, for some
bridgeport machinery, I am going to use 4# ga wire And A friend told me that it would be ok to use 1" emt to run 4 4#ga wires thru this tubing,
but i wanted to go with 1 1/4, what would be the proper tubing size to run four 4# ga wire.
the machines are around 4 amps so I was going to use A 20 amp breaker.

 

[jshaw2]

Re: 3 phase wiring and #4 ga and proper emt size

Personally I would use 12ga. THHN wire (20 amp rating)and run it in 3/4". Sure would save a lot of time and money.

 

[hurk27]

Re: 3 phase wiring and #4 ga and proper emt size

Why the #4 AWG if the Bridge Port only pulls 4 amps? #12 would be just fine unless the run is over 1000' Then you would only need a 1/2" conduit. But 4 #4 in 1" would be tight and 11/4" would be better.

But as far as the NEC goes.
EMT allows 4 #4 in a 1"
RMC only allows 2 #4 in a 1"
Look at chapter 9 for more answers

 

[iwire]

Re: 3 phase wiring and #4 ga and proper emt size

He is asking about the feed to the sub panel I think.

I would go with 1/1/4" EMT, four 4 AWGs in 1" while possible, would be difficult.

EDIT: 4 AWG will need a 90 amp breaker maximum, I would suggest using 3 AWG with the 1 1/4" EMT.

Just a wild guess on my part that you have a 100 amp panel.

[ January 09, 2004, 03:26 AM: Message edited by: iwire ]