A/C Units

[voltchaser]

I am installing service to new AC units which have been upgraded to 200A from 100A.The existing conduits are 1.5,they are about 30ft with 2 to 3 90s each.Is the conduit ok to use.The MOCP is 175A.But the Breaker feeding it is 200A.3/0 wire is called for.What do you think.Thanks in advance.

 

[bob]

Re: A/C Units

You must use the MFG max OC device recommentation and the MFG minimum circuit ampacity. If the MGG specifies a 175 amp breaker then that is what you use. When you say 3/0 is "called for", what does that mean. Is it the specs of the MFG?

[ October 26, 2004, 07:15 PM: Message edited by: bob ]

 

[voltchaser]

Re: A/C Units

Sorry,I should have said the breaker I am using is 200A.So I am running 3/0.I am fusing it down at the disc. to 175.The problem is that if I am reading the code right,I can run 3 3/0 in an 1.5 conduit.Is that right? And if it is,it just seems tight.

 

[612278]

Re: A/C Units

Hello-

NEC chapter-9 appendix C. Conduit fill chart for EMT> "say's" 3-3/0 in a 1 1/2" emt. with the amount of 90's you have I wouldn't try it.

 

[wirenut1980]

Re: A/C Units

The NEC appendices as you know are not required to be followed and are suggestions. Also, the NEC is only concerned with safety and it does not take into consideration ease of pull, or ease of installation, or not even good design practice. In my limited experience in talking with installers, the max amount of conductors suggested in the table you are referring to, has always been too tight of a pull for them...especially with the 90 degree bends.