One (of 3)of my jobs is working for the government (FAA). One of the "engineers" said that he is allowed to make the following circuit: 30A 208 VAC ckt. to splice box via 8 AWG (wire remained from previous installation) for a hard wired coffee machine. From splice, 120 VAC 15A recp for cash register (via 10 AWG wire, probably for the same reason. How did they get the wire onto the device? I haven't seen that portion yet.). I'm guessing the "engineer" is basing it on 2002 NEC 210.19(A)(4). It seems to be kinda dangerous to me. Suppose that the cash register decides to nuke itself while the 30A breaker sits there fat, dumb and happy. The installation is in a small privately run cafeteria. 210.21 (B)(3) says all the devices on the circuit have to rated for the same amperage (Excep. arc welders). What say you?
I would say, welcome to the guv'mint. It is certainly a violation but the government asserts AHJ power (sometimes recklessly). I would try to convince them this is a bad idea but if they disagree, walk away.
Gummint has to follow NEC, too. Well, when we feel like it, at least
This is a violation of the UL listing on the receptacle and probably the coffee machine- if would be one thing if they were both listed for 30A, but that's not the case. If he wants to use a single 30A circuit, that's OK, but OCP would be required at the load. The receptacle especially worries me- it would be far too easy to overload it.
If the AHJ wants to allow it (and, honestly, it's within their right) make sure they put it into writing. I can't see them signing off on this, though.
Steve, the problem is that the installation is in a Fed gov't site. I deal with this on a daily basis. Although the branch I work for has taken the steps to accepted and manage by the appicable codes, every so often, someone will play the "we be the gov'ment" card and the problem just disappears. With government funding the way it is and if not directly connected to national security, it will only get worse.
The only difference on a federal site is that the AHJ typically has a vested interest in that site. Depending on the site, they may not even be an expert, they may just be the responsible manager. It's easy for the city AHJ to fail you because he doesn't have to face any of the reprocussions. But when the inspector has to pay the repair bill for any violations they find, and take the heat for any delays and other problems... they apply operational risk managemant and tend to 90(C) a bit more liberally than one who completely ignore the whole "economics" and "operational impact" portions of the equation.
To the FAA, the difference in cost between 1x 30A and 2x 20A is negligible- there's nobody out there who's going to risk his neck and his facility for the sake of saving $200. At least among those AHJs who understand the risks involved. They may simply not be aware- I know it's hard to believe, but engineers sometimes make unintentional stupid mistakes, too I'd raise it as an issue of concern and let the engineer and AHJ make the decision. If they're OK with the risk and say go and give it to you in writing, the design is legal and you're OK.
FYI, I work for the DoD and hold AHJ responsibility at a number of federal sites.
