Conductors and Breaker Size for RTU's

[Daledo]

Hey there...just wondering if anyone can give me a quick, easy, general rule of thumb for figuring out conductor and breaker sizes for roof top units. There seems to be a lot of RLA's, LRA's, FLA's, MCA's, MOCP's, Maximum Breaker, Minimum
Fuse, etc. figures on the nameplates of these things, and I was hoping to clarify which of these are important to us, as electricians, to use. Thanks in advance [img]smile.gif[/img]

[bigrockk]

Check out this article, it should help you understand the nameplate data. It makes reference to the Nec and of course you will have to reference the CEC but it is a good article.

http://www.iaei.org/magazine/99_d/simmons.htm

[CRM]

The label should have all the information you need, the first thing I look for is the voltage, single or three phase, minimum circuit ampacity(wire size), and maximum overcurrent protection, if possible I would go with the maximum overcurrent rather than the minimum, to prevent the breaker from tripping on startup.

[Daledo]

Thanks a lot guys. That's what I was trying to explain at work the other day, but the other guys were convinced that we needed to take 125% of the largest motor (the compressor) then add the other motors for the conductor size. I told them that it was already calculated in...now I have a website I can show them. Cheers [img]smile.gif[/img]