Class 1 Div 2 sealing

[NovInc]

First post here.

Can you please help me clarify the definition of "hermetically sealed" for class 1 div 2 (grp C&D)? If I have a level switch with a non-sealed relay switch in a Nema 4x enclosure, can I consider that the o-ring on the lid and chord grip seal the enclosure against vapors?

If not, my next question is if I get the switch with the EP enclosure, do I need an actual seal off for the cable or can I seal it some other way (quick connect fitting, chord grip, etc)?

They don't offer this particular switch with a nonincendive rating, and I'm trying to avoid conduit.

Thanks - Ty

 

[petersonra]

First post here.

Can you please help me clarify the definition of "hermetically sealed" for class 1 div 2 (grp C&D)? If I have a level switch with a non-sealed relay switch in a Nema 4x enclosure, can I consider that the o-ring on the lid and chord grip seal the enclosure against vapors?

NO! A hermetic seal completely excludes any potential for any outside gas to enter the switch body. A normal gasket does not do this.

If not, my next question is if I get the switch with the EP enclosure, do I need an actual seal off for the cable or can I seal it some other way (quick connect fitting, chord grip, etc)?

They don't offer this particular switch with a nonincendive rating, and I'm trying to avoid conduit.

Thanks - Ty

I think your best bet is probably some kind of IS barrier system.

No offense but I think it would be best if you allowed someone with more knowledge in this area to deal with this problem. It is difficult at best to give advice on a forum like this because most of the time only some of the needed information is available.

 

[rbalex]

Hermetically sealed units would typically be reed switches, mercury switches, some ?ice-cube? relays and similar constructions. For all practical purposes, ?hermetically sealed? is ?airtight? and, as Bob (petersonra) pointed out, a simple ?o-ring? won?t do the job. On top of that, you would still need some wiring method entry into the enclosure and, conduit or not, any o-ring would be by-passed.

You can still avoid conduit. For a non-explosionproof system, intrinsically safe and some non-incendive systems would work. You need to be very careful documenting them and collecting proper ?control diagrams? for a compliant installation.

With an explosionproof enclosure, there are a few ?cable only? wiring methods, such as Type-TC or PLTC, that are acceptable in Division 2. They will still require a seal at the enclosure. See [2005 NEC] 501.15(E).

 

[NovInc]

Thanks for the help.