Hello all,

My volunteer emergency response team has a 20-foot enclosed trailer to haul our equipment, with a small office area for radio communications. Being "that electrical guy," I've been asked to review the existing 120/240 volt installation for adequacy and code compliance. I'm using 2007 California Electrical Code, which is based on 2005 NEC.

It seems to me that this most closely meets the definition of a recreational vehicle, so it should be evaluated according to article 551, with the exception granted by 551.4(A) because it isn't used as living quarters.

My problem is that I can't understand what exemption is being offered by 551.4(A), which says that the trailer "shall not be required to meet the provisions of Part I pertaining to the number or capacity of circuits required." Part I has no such provisions. The branch circuit requirements are stated in 551.42, but that's in Part IV.

Ok, so if I ignore the branch circuit requirements in 551.42, then how can I verify that the power supply assembly meets the requirements of 551.44, or the plug requirement of 551.46(C), when those articles refer only to the configurations permitted by 551.42?

Your opinions and advice are much appreciated.

Regards,
John