Madlabs
this is my thinking on the subject
we need to be concerned about codes and the NEC "if" we do any of the following
1. live in an area where an electrical inspector is a reality
2. live in an area that enforces codes
3. are concerned with insurance and insurability
4. are building stuff that man or beast will inhabit or have access to.
(most particularly if people will be living within the same confines or in an area directly attached to our power room)
if any or all of these are concerns then you ought to go with what the NEC calls out for at a minimum and also look into local codes for what their mandates are.
if on the other hand, your power room is such that it is clearly separate from living spaces, is made of fireproof materials, and is secure so that no one can have access except for you or other qualified maintenance folks, and you can assume the risk for the remote possibility of the building burning down and catching something else on fire... i see no reason to follow the letter of the law. the reality is you are building an appliance and the NEC or other local codes have no authority over what is inside the case.
the only possible issue might be one of UL approval of your appliance, but that is only an issue should the thing burn down and burn down your insured house should the insurance company have an issue with it. (which they probably would if it was found to be the cause of your house burning down)
me i would just build it with a comfortable margin of safety, spaced so it would be unlikely to catch something else of value on fire, and build it out of a material that is as fireproof as realistic. your steel container is what i would think of first, maybe a cement block structure or similar.
what goes on inside that structure technically is no one's or no entities business provided it is not a threat to others.
if it were otherwise, we would have NEC and all sorts of code boys pawing around our shops, looking over every diy project we could dream up.
where i live there is no code enforcement at all, nobody cares if it is NEC approved except for the insurance man. even then many folks choose not to insure or to self insure because the cost of housing here is peanuts compared to most area's of the country.
the insurance on my house is such that i could pay for another like place here in town with about 15 years worth of premiums. most houses sell for less than half the down payment of similar houses in bigger markets.
here we can use common sense, an we accept a certain level of risk so long as that risk is not to others or their property.
bob g
