This being a rather diverse group, lemme throw one out here.

High Voltage (OK, Medium - 13.8kv) room containing network protectors, switchgear, and transformers, liquid and dry.

Air - Positive or negative pressure? Arguments are - Negative and all the dust comes into your room, Positive and in case of fire all the fumes blow into your egress hallways. Natural ventilation is highly impractical, or not possible.

I can find no code pointing to either. Does anyone have any info on if it should be positive or negative? Article 450 quotes an ANSI document C57.12.00-1993 but I don't have it, and can't even find it on ANSI's website.

Arguments OK, but I prefer code references.

Thanks.