General Purpose Switch in Hazardous Area

[zimmerDN]

Does the OESC in Ontario allow the use of a general purpose level switch in a Class 1 Div 1 (Zone 1) location if the circuit is designed with intrinsic safety barrier and wiring methods?

 

[zappedagain]

Check your barrier's control drawing. Your safety barrier is designed to be safe at open circuit and at short circuit. What else can the switch do? As long as your switch doesn't have more capacitance or inductance than the barrier can support I don't see a problem.

Z

 

[DRWeig]

Not 100 percent certain about Ontario, but in the US and EU, a common switch is classified as a "simple apparatus" and does not need to be listed for the zone or area as long as it's protected by a barrier.

I've always used MTL 5011B. It's an isolator as well as a barrier for dry contact switches. Grounding restraints aren'ts as rigorous. You can also talk to the MTL tech support, they're great.

http://www.mtl-inst.com/contact/C223

And no, I don't work for MTL -- but a I used to work for a distributor. I'm a big fan of their products and service.

Best to you,

Goober Dave

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[zimmerDN]

The details of the instrument is not completely clear at this point.

I believe it will likely be a simple float (micro) switch like you would find on a sump pump.


Why does MTL rate all their digital input barriers for Class 1 Div 1 Group A? What if the location is Group D?

 

[makesparks]

Class 1 Div 1 Group A is the most severe gaseous hazardous location. If the barriers will work safely with that condition, it will be fine for Group D.

 

[DRWeig]

Your microswitch qualifies as simple apparatus as well.

Best to you,

Goober Dave

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