Manual pull station as simple apparatus

[azuniga99]

Hello I am building a Class 2 division 1 group G facility and wanted to look into using I/S barriers for the manual pull stations circuits of a fire detection system. Reading NEC article 504 a pull station could be classified as simple apparatus, I realize that this would mean sepparating the wiring from the pull station from other non I/S signaling decvice inside the hazardous area. So the question is: if I use a barrier and keep the wiring separate, could I consider a NEMA 4X manual pull statation a "simple apparatus" as part of an I/S circuit, and avoid using more expensive explosion proof pull stations?

 

[rbalex]

For what it's worth, explosionproof equipment is neither required nor acceptable in Class II unless it is identified for it See Section 502.5.

That said, the wiring design you described would be acceptable IF you're willing to jump through all the other hoops required by Article 504 including securing a control drawing [504.10(A)] which you aren't permitted to produce yourself. Remember the grounding/bonding requirements are the still same as the classified location [504.50] they're installed in and you already mentioned wiring restrictions. That wasn't an exhaustive list.

In my opinion, the "savings" of intrinsically safe systems (and nonincendive systems) is marginal at best unless the overall facility has a massive distributed control system.

 

[gadfly56]

Why reinvent the wheel? Cooper makes a pull station that's listed for Class II Group G. See here.

 

[rbalex]

It's also explosionproof, which he wanted to avoid.

Truthfully, that will be a common "problem". Most internally arcing devices that are explosionproof are also dust-ignitionproof. In my opinion, dust-ignitionproof shouldn't usually be required in Group G, nevertheless it is.

 

[gadfly56]

It's also explosionproof, which he wanted to avoid.

Truthfully, that will be a common "problem". Most internally arcing devices that are explosionproof are also dust-ignitionproof. In my opinion, dust-ignitionproof shouldn't usually be required in Group G, nevertheless it is.

D'oh! :slaphead: Missed that part at 1:00 in the morning. If it's just one pull station, get one that's XP with the proper listing. You'd never be able to justify the cost of setting up just one station as an IS simple apparatus.