Per the Forum rules, it is obvious my previous post (Class I Div.1 Conduit Entry to Purged Enclosure) can not be answered here, as it requires pure rules interpretaions, not easily defined, which could be used in law suits if devices fail. Sorry if I caused any problems.
I read your posts as they were coming out. You didn't cause any problems. You just asked questions is a sufficiently vague manner that you got sufficiently vague answers.
And you did get a pretty solid answer - put a seal on the conduits entering the cabinet.
...So, where does one turn for truly interpretive type rulings concerning the NEC on pressurized/purged enclosures, as I have a definite "gray area" problem that has had to have been addressed before?
You pay a registered engineer to come up with a design and put her stamp on it. All the gray areas stem from: None of these codes you cite are design guides. And since they are telling you to design it - then that's what you need to do.
This forum does plenty of DIY engineering. And some of it is pretty good. But, it is all worth what you paid for it. The concept that you were going to get free DIY engineering suitable for acceptance by an AHJ is ludicrous.
Generally speaking, the AHJ has no knowledge of how a purged system should work. You show up with a design by "MH forum DIY engineering" hopefully she will throw you out. An alternative is for the drawings to be signed by your company's engineers. Most states have a section that does not require a stamp if the engineering is not for hire, not public occupancy, and not recra.
So where do you go
You are an engineer - do you own research. If you are out of your area of expertise - hire one that has that knowledge.
ice
