Separation of Intrinsically Safe (IS) Conductors In Panel

[gerbonic]

I am retrofitting a panel with IS Barriers and I am looking for ideas/ advice from people who have added IS barriers in a panel where there were no IS barries before. I am relying on NEC2014 Article 504.30(A)(2) for guidance. My first thought is to divide my wire-channel/Panduit into two channels of half the width and run IS on one side and non-IS on the other. My ultimate challenge is how to handle the siuation where IS wiring may have to cross over non-IS wiring to make it form the channel to the barrier or from the cable entry into the channel. I may even be able to implement the seperation by 2 inches and not need the new wire channel, but how do you handle the wire crossings?
Has anyone added conduit (flex or hard pipe) inside an enclosure in order to maintain separation?

Thank You.

 

[rbalex]

See the Section 504.30(A)(2) FPNs/INs, depending on the NEC edition.

My personal opinion is the ISA has gotten a lot of instrumentation system operation rather than actual safety included IS/NI design requirements. See Section 504.1 FPN/IN.

 

[srinivasan]

I am retrofitting a panel with IS Barriers and I am looking for ideas/ advice from people who have added IS barriers in a panel where there were no IS barries before. I am relying on NEC2014 Article 504.30(A)(2) for guidance. My first thought is to divide my wire-channel/Panduit into two channels of half the width and run IS on one side and non-IS on the other. My ultimate challenge is how to handle the siuation where IS wiring may have to cross over non-IS wiring to make it form the channel to the barrier or from the cable entry into the channel. I may even be able to implement the seperation by 2 inches and not need the new wire channel, but how do you handle the wire crossings?
Has anyone added conduit (flex or hard pipe) inside an enclosure in order to maintain separation?

Thank You.

We have used IS barriers for Ex'i' transmitter application but we have not done any special arrangement. Separate terminals and separate line up to barriers will do your work....

 

[rbalex]

We have used IS barriers for Ex'i' transmitter application but we have not done any special arrangement. Separate terminals and separate line up to barriers will do your work....

You are correct that separate terminals and separate lineups to the barriers and terminals is all that is actually necessary for intrinsically safe systems; however, it is still not compliant with the NEC requirements. The wiring separation requirements beyond terminals are more related to control signal corruption than immediate safety requirements, just as they are the real reasons for wiring separations in Article 725.

As I mentioned, the International Society for Automation (ISA), (formerly the International Society for Measurement and Control, formerly the Instrumentation Society of America), has managed to have many of their pet control systems criteria adopted in the NEC, especially Article 725. This has usually been with no more substantiation beyond, "Gee, that seems like a good idea." That isn't to say I believe they are bad criteria, but they are design and not generally direct safety requirements. Despite its statement to the contrary [Section 90.1(C)] the NEC is becoming a "design manual" and a poor and confusing one at that.