How do I tell?
The area that I was wondering about is four feet to the right of the opening and back away from it by 20". If that makes sense. I wanted to run a piece of EMTon strut along the floor then change over to flex above 24" to go into a disconnect. I generally stay on the side of caution but trying not to over do it if we don'thave to.
It was speced by an eengineer at the company Iwork for that 3' from all openings are classified as class 1 ddivision 2. But wondered if out of then 3' zone if a raceway can be located below 18".
Typically, the classified envelope would drop all the way to grade from the 3' "bubble" - thus it is possible that there is an 18" classified location (or more) above grade. However, there is no requirement in Article 516 to extend the classified envelope beyond that.
Depending on possible boundary seal requirements, wiring methods outside the envelope(s), may be anything otherwise appropriate to the ordinary location.