Class 1 Division 1 Sewage lift station

[Sierrasparky]

Hi.
In a Sewage lift station Class 1 Division 1 Group D ,is it assumed that the Float switches in the tank are to be intrinsic?

 

[rbalex]

Not necessarily. I never did, but I'm not a big IS fan to start with. IS installations are far more complex than most think and are rarely justifiable for a single control circuit. Article 504 is just the beginning, and ANSI/ISA-RP 12.06.01 is OSHA enforceable under the general duty clause.

 

[Sierrasparky]

Thank you.

So basically a can of worms.


Is there a situation where you have no choice but to wire IS?

 

[rbalex]

Dunno. Personally, I've never been in such a situation for a single circuit and I can't imagine where it would ever be an absolute necessity. Occasionally, it is inherently offered in a few small "package" systems and it's OK.

Where IS is the major DCS, it can be pretty cost effective for a medium to large facility. It can also often be justified where the weight of explosionproof equipment in an installation is a consideration, such as offshore drilling rigs which usually have many Class I, Division 1 compartments.