Unlike your typical household electrical switch, the heavy-duty explosion-proof switch is designed to contain an explosion. If there is explosive gases in a room, the gases eventually do get inside the conduit in devices. So any time you throw a switch or plug something in or a thermostat triggers a fan to turn on or a heater to turn on, there is an arc or a spark that does occur inside the conduit. If gases are present in that conduit, there is a little explosion going on. The system is designed so that the explosion is contained within the conduit system, within the devices. These devices are heavy duty, they can take the explosion that happens, and any spent gases have to escape through at least 5 layers of threads or through honed surfaces where the device matches up with its junction box. There’s so much surface area on those devices that the gases cool to the point where, by the time they escape, they’re harmless.
All right, let me illustrate what I’m talking about here. This is a typical T Body. It is a fitting for the conduit to chase wires through, and this is the cover plate. These surfaces are honed and machined to very tight tolerance and when you put them together, they have a nice, tight seal. However, gases are very fine. They can escape through that surface, but there’s so much surface area there, so many millimeters, that as the gas travels over that surface, it’s cooled and becomes harmless.
Explosion-proof or hazardous location system is a system. You can’t have some parts that are explosion proof and some parts that are not. Everything that you need in ‘explosion-proof’ is available. Here is a sample of a thermostat, explosion proof. Junction boxes have to be explosion-proof. All the pipe has to be heavy duty, thick wall conduit, fully threaded connections.
This is a seal-off; its job is to keep gases and explosions from migrating through the rest of the system. Once the wires are pulled through this conduit, this port is opened and there’s a packing that’s stuffed in there, and then closed. Through this upper part, a resin part gets stuck in there and then it hardens and it seals off completely, and it isolates this section of the pipe from that section of the pipe.
Shelter Works electricians are trained in explosion-proof and hazardous location applications, but we need input from you. Talk to your engineer, figure out what kind of hazard you have in your application, and we can design a system that will work for that hazard.
If it was built by Shelter Works, it was built for life.