Intrinsic Safe Circuit Article 504.2

[hughb3]

504.2 Definition: Different intrinsically safe circuit
504.30 (B)From Different intrinsically safe circuit conductors.
I have an industrial control panel with extensions in to an intrinsic area. Meaning that I have inputs from the intrinsic area going to intrinsic barriers in my control panel. For this I maintain the 2? of separation required for wires in this area and section the area off with a 20 gauge grounded partition as required by 504.30 . My question is, what is 504.2 Definition of different intrinsically safe circuits and 504.30 (B) trying to say? Is this saying that I can use dry contacts in my panel from a standard relay to trigger my intrinsic relay input if I use shielded wire for the connection between the two?

 

[rbalex]

Re: Intrinsic Safe Circuit Article 504.2

The 504.2 definition speaks to the circuits as a whole, including ?sources.? The concern is that untested physical interconnections may create a ?NON-intrinsically safe? condition, especially if ?sources? may become inadvertently paralleled.

Section 504.30(B) speaks specifically to the conductors. The requirement is that all conductors in close proximity be ?powered? by the same intrinsically safe ?source? or there be a suitable physical barrier between them.

It is important to recognize, that in the second case, both ?sources? are still intrinsically safe; therefore simply using shielded wire between intrinsically safe circuit conductors and non-intrinsically safe conductors is NOT acceptable.