Emergency Lighting in Pressurized building

[KarlS]

If the exterior of a building is class 1 div 2 with pressurization system is there anything in the NEC that states you need to use a class 1 div 2 emergency light fixture? Can you use a standard Emergency light with battery backup due to the Press system.

 

[OTT2]

If the exterior of a building is class 1 div 2 with pressurization system is there anything in the NEC that states you need to use a class 1 div 2 emergency light fixture? Can you use a standard Emergency light with battery backup due to the Press system.

Is this luminaire within the hazardous classified location? 501.130(B)?

 

[weressl]

If the exterior of a building is class 1 div 2 with pressurization system is there anything in the NEC that states you need to use a class 1 div 2 emergency light fixture? Can you use a standard Emergency light with battery backup due to the Press system.

Can you clarify?

1. What is the Cl/Div on the inside of the building?
2. What is the Cl/Div on the outside of the building?
3. What NFPA 496 type purge do you intend to use?
4. Is the emergency ligh fixture located on the inside our the outside of the building?

 

[renosteinke]

It's important to note that the use of 'rated' equipment is but one of several different approaches to dealing with hazardous locations.

The NEC recognizes these other approaches. One such approach is the pumping of clean air into electrical enclosures - effectively preventing a hazardous atmosphere from forming. Under those conditions, it's common for 'ordinary' or gasketed -but otherwise unrated- equipment to be used.

I remember my apprentice text, which made the blunt statement "it is NEVER the responsibility of the electrician to determine the extent or design of a classified location." The situation you describe is one example of why such a statement makes sense.

You have to pass the buck to whoever specified the part and designed the pressure system.

Now, if you are being asked to just hang a light - without it being part of the pressurized piping, or in such a protected location, then you are right to be concerned - and the answer is DON'T DO IT.

 

[KarlS]

The Building exterior is in a Class 1 div 2 area. Only if there is an even the area will become class 1 div 2. The building interior is a general classfication area. The pressurization is type Z with 20ft fresh air stack. The press system keeps the building interior gen purpose. I am mounting the combo emerg/exit lights over the interior doors. The ones with batt and 90 min back-up.
Nothing else in the interior is classified.
The question was what if the power was lost and now no press and emergency lights come on.
The area still would not pose a hazard unless there was an event and gas filled the area on the exterior of the building.
Then eventually the interior would have gas.

 

[petersonra]

Generally speaking, if you are pressurizing something to reduce the classification inside the enclosure from C1D2 to non-hazardous, there is no requirement to do anything at all if the pressure is lost. you do have to indicate the loss in some way, but no requirement to do anything.

I don't know off hand if pressurizing a room operates under the same basic rules as an enclosure. If it does, then my answer would be no special light is required inside the pressurized area.