class 1 div1

[ronlove]

In class 1 div1 if I come out of an explosion proof box to a device (non arcing) do I have to have a seal between the listed explosion proof box and the device? can you use flexible nonmetallic conduit for the connection?

 

[Jhaney]

I am currently working for a natural gas transmission company and they follow the NEC very closely. That being said I don't have my NEC in front of me, but when constructing anything in class 1 div 1 area we use seal offs everywhere.
Example: I have a temperature transmitter on a gas pipeline connected to it is a sealoff next FMC which connects directly to a listed explosion proof box then another sealoff which connects to RMC going to a meter building.
Hope thats not too confusing.
I was going to attach a schematic but couldn't get the size down small enough.:-?

 

[don_resqcapt19]

In class 1 div1 if I come out of an explosion proof box to a device (non arcing) do I have to have a seal between the listed explosion proof box and the device? can you use flexible nonmetallic conduit for the connection?

You can't use flexible nonmetallic conduit in a Class I, Division 1 location. A seal will not be required at the enclosure if the conduit is smaller than 2" and there are no apparatus, such as switches, circuit breakers, fuses, relays, or resistors, that may produce arcs, sparks, or high temperatures that are considered to be an ignition source in normal operation

 

[Mule]

You can't use flexible nonmetallic conduit in a Class I, Division 1 location. A seal will not be required at the enclosure if the conduit is smaller than 2" and there are no apparatus, such as switches, circuit breakers, fuses, relays, or resistors, that may produce arcs, sparks, or high temperatures that are considered to be an ignition source in normal operation

Ok, my art 500 head is old, but I wouldnt think that you can leave a exp enclosure without sealing the conduit at the first thread out, OR, if you attach another exp enclosure with no threaded junctions.....where am I loosing what you saying? In my mind you can't leave the exp proof enclosure opening unsealed no matter what the size....can you give me a code reference?

 

[don_resqcapt19]

Mule,
Take a look at 501.15(A)(1) in the 2008 code.

(A) Conduit Seals, Class I, Division 1. In Class I, Division 1 locations, conduit seals shall be located in accordance with 501.15(A)(1) through (A)(4).
(1) Entering Enclosures. In each conduit entry into an explosionproof enclosure where either of the following apply:
(1) The enclosure contains apparatus, such as switches, circuit breakers, fuses, relays, or resistors, that may produce arcs, sparks, or high temperatures that are considered to be an ignition source in normal operation.
(2) The entry is metric designator 53 (trade size 2) or larger and the enclosure contains terminals, splices, or taps. ...

 

[Mule]

Mule,
Take a look at 501.15(A)(1) in the 2008 code.

Thanks, I look at it this evening..............