ECN Forum Forums Photo Discussion Forums Violation Photo Forum Hazardous (Classified) Location - Rusty Threads and Corrosion!

Contrary to what many think, explosion-proof equipment does not prevent an explosion but “contains“ it when it occurs in an electrical enclosure. Exhaust gases/flames are cooled as they pass through many cover threads. http://www.appletonelec.com/PDF/Hazardous1.pdf http://www.appletonelec.com/PDF/Hazardous6.pdf

Bjarney, As I said I have not done much of this type of work but I agree with you.

Most electricians do not understand the equipment contains an explosion inside.

Kind of a strange concept in it's own right.

The last explosion proof job I was involved with was all PVC coated components.

480 volt 3 phase outlets and control stations. $$$$$

OK, so just to make sure I have this right, "explosion proof" keeps the sparks and flame inside the box, rather than allowing it to enter the explosive atmosphere around it?

Would it survive an arc flash?

But, the box with all the wires hanging out of it looks like a meter socket.

See the following definition in Article 100 and Article 500.


I am pretty sure that the enclosure where the wires are exposed is not a meter socket. Maybe someone can help us with a reference.

Think good yes that is right, pretty cool.

Mean Gene I agree that looks like a meter socket but that is a junction box for hazardous locations.

The cover is a very heavy solid disk that threads into that round hole.

Very fine threads it takes many turns to full tighten it.

You do not even want to think about the cost of this device.

One price of this type of equipment I know is a thermostat for heat trace cable.

Normal location one would cost us about $20.00 the ones we need for hazardous locations cost us almost $800.00 and it is about the size of the round j box on the left between the switches.

Check this out for a picture of a similar box. http://www.hubbellonline.com/wiring/killark/pdf/2SecF/SecF55-F56.pdf

The j-box on the far wall looks similar to an Appleton GUBB catalogued at http://www.appletonelec.com/pdf/K-2thru8.pdf The intent is not to stop hazardous vapors from entering, [that’s a loosing battle] but if contained vapors or gases ignite, then the threads or lapped surfaces “cool” the combustion products to limit high-temperature propagation outside the enclosure, reducing the chance of igniting airborne materials outside the enclosure.

NEC Chapter 5 wiring is a whole different animal and almost needs piecemeal assembly drawings to install correctly.

Petrochems, distilleries and NASA launch pads are unique in that regard. As can be imagined, the liability is tremendous.

Reminds me of a guy with whom I used to work. He could ID old auto parts at a glance. People would bring stuff in to try to stump him.


Fireworks factories?

Boy Howdy, TG. That's a little trickier, for vapors and dusts are handled a bit differently.