500.8(B)(1) interpretation/implementation

[not_a_EE]

How would you interpret 500.8(B)(1) for a gas/vapor that has an autoignition temperature of 25 deg C (yes, 25 deg C, not missing a 0 here)? Does that basically mean you can't use any electrical equipment in the classified location?

 

[petersonra]

How would you interpret 500.8(B)(1) for a gas/vapor that has an autoignition temperature of 25 deg C (yes, 25 deg C, not missing a 0 here)? Does that basically mean you can't use any electrical equipment in the classified location?

(B) Approval for Class and Properties.
(1) Equipment shall be identified not only for the class of
location but also for the explosive, combustible, or ignitible
properties of the specific gas, vapor, dust, or fibers/flyings that
will be present. In addition, Class I equipment shall not have
any exposed surface that operates at a temperature in excess of
the autoignition temperature of the specific gas or vapor.
Class II equipment shall not have an external temperature
higher than that specified in 500.8(D)(2). Class III equipment
shall not exceed the maximum surface temperatures specified
in 503.5.

You are going to have to condition the space to keep the ambient temperature down anyway. I think you are going to have to get special permission from the AHJ for this kind of thing., which likely means hiring a PE with experience in dealing with this kind of situation.

It is like working around explosives. There is nothing in the electrical code that covers it.