Maximum temperature allowed inside an EXD panel

[ArchieMedes]

Hi,

I would like to ask what is the maximum temperature allowed inside an EXD panel? If there would be a tripping setpoint on the temperature inside the EXD box what would that setpoint be?

Thanks..

 

[rbalex]

Do you mean "AEx d" or simple explosionproof?

 

[ArchieMedes]

Explosion proof panel (EXd)

 

[rbalex]

Not to be too hard on you, but "EXd" is meaningless in the NEC.

Explosionproof equipment is defined for Class I, Division rated equipment in Section 500.2 and the corresponding protection technique is in Section 500.7(A).

“AEx d” is for Class I, Zone rated Flameproof equipment defined in Section 505.2. The “A” is essential. See Section 505.9(C)(2). Its corresponding protection technique is in Section 505.8(A).

Explosionpoof and Flameproof are similar concepts but they are not exactly the same. They have different test standards.

That said, there is no internal temperature limitation on explosionproof equipment. The temperature limit, if any, is on the external surface(s) and will be listed with the “T-Code”. See Section 500.8(C). “AEx d” Flameproof may, but not necessarily, have an internal temperature limitation; if so, it will also be listed as a “T-Code.” See Section 505.9(D).

 

[ArchieMedes]

Rob,

Thanks for the reply. With that, can I say that the only limitation would be the "ambient" rating of the components inside? The internal temperature of the EXd box becomes the ambient of the components inside.

Thanks a lot....

 

[rbalex]

I would suspect most internal components are rated for a 40C ambient. Some may be higher and, of course, if the components are heat producers themselves, they will affect the ambient.

And EXd is still meaningless in the NEC.

 

[petersonra]

And EXd is still meaningless in the NEC.

yet, manufacturers continue to peddle such equipment in the US.

 

[rbalex]

yet, manufacturers continue to peddle such equipment in the US.

Caveat emptor