In the 05 code it states you need a support within 3 feet of an outlet box when using EMT per 258.30(A). If I have a peice of conduit ran from an outlet box to another outlet box and the EMT is less than 3 feet, do I still need a support?
Ive never heard this... Where have you read this in the NEC? I'm staring right at it in the 2005 handbook and it does not say anything of the sort. What would be the drawback of concentric/eccentric knockouts? Seems to me this would make no difference in a supported or unsupported method.
While not commonly enforced, under the 2005 and earlier codes, all conduits between enclosures, no matter how short require a support. The real question, when the enclosures are within 3' of each other, is, "can the conduit termination at the other box be considered the support for the conduit"? If the conduit termination can be considered the required support, then there would have been no reason for the code panel to accept the change that appeared in the 2008 code.
This topic came up at a changes in 2008NEC class I was in. The instructor showed us a photo of a less than 36" x 3" RMC nipple between two enclosures. We concluded that code required a support on this raceway. We also concluded that the raceway would in reality support whatever strap was used more than the strap would support the raceway.
I would encourage any inspector that wanted a strap on that install to take a 5 pound hammer and beat the hell out of the strap and the raceway and see which one fails first. Of course he still can make me put a strap on it even after I make my point.