Class B ceiling install. Ceiling is sloped

Fordean

Senior Member
I have a Garage with 80 x 80 flat ceiling. From the Bottom of Deck to 18 inches is Class B for Natural gas. I have no problems Here I can understand the 18 inches definition.

Problem is the Slope roof. Is it along the whole slope 18 inches. Or just 18 inches at the peak. I am install Trapeze at 24. Below peak. EMT where they will be below the 18 Inch Class B area.
 

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rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
To be honest, I have no idea what you mean about Class B in relationship to classifying your locations. Natural gas is Group D.

That said, the right-hand figure in your third diagram would be correct; i.e., the 18" would be measured from the peak. If properly ventilated, it may not need to be classified at all. See Table 511.3(D).
 

Fordean

Senior Member
To be honest, I have no idea what you mean about Class B in relationship to classifying your locations. Natural gas is Group D.

That said, the right-hand figure in your third diagram would be correct; i.e., the 18" would be measured from the peak. If properly ventilated, it may not need to be classified at all. See Table 511.3(D).
Acuttally better said Class 1 Division 2 Class b was a term I learned in the early 90s Stuck with me
 
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