Hazardous area boundaries

[Mauricio Mtz]

I have a question about the boundaries. Generally a turbine compartment is classified as a Class 1 Div 2. The haz gas boundary is the turbine enclosure wall and we need to add a sealer in order to run the conduit from the haz area to the non classified location.

My question is for the hardware installed outside. There are some valves and a bubble is indicated around the valves, the bubble indicate that it is a Class I Div 2 hazardous area. There is a conduit running from the solenoid valves (explosion proof) and switches (explosion proof) there are sealers on each solenoid valve and each switch. There is a junction box near the bubble. The junction box contains only terminals and the switches and solenoid valves are wired to that junction box. According to 501.15 (A) the sealer is required if the entry metric of the junction box is trade size 2 and the JB contains terminals. The trade size is 1.5 therefore there is not need to add a sealer. My question is if we need to add a sealer on the conduit run, on the bubble limits due to the haz area change.

thanks

Mauricio Mtz

 

[rbalex]

I don't even know where to start.

1.) The electrical area classifications are questionable. What standard was used?

• It is difficult to justify the enclosure's internal classification as Division 2. It should either be unclassified or, if there is any possible internal source, Division 1.
• What is the "source" for the Division 2 "bubble" around the valves and solenoids?

2.) Assuming the electrical area classifications are correct:

• The solenoids are not required to be explosionproof and no seal is required except a boundary seal, in which case it doesn't need to be explosionproof. [See Section 501.15(B) - read it all] The valves may need to be explosionproof. If so an explosionproof seal is required. Depending on it's location it may also be a boundary seal.

3.) If the junction box is out side the classified locations, it doesn't require seals. Section 501.15(A) only applies to Division1


The odds are you are already grossly over-engineered.