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Seals in Class 1 Div1

Seals in Class 1 Div1

Seals in Class 1 Div1

Coming out of Nema 7 with 1" conduit max.
Have seals installed at each entry to the enclosure. All my instruments are C1D1 rated, and switches that aren't are wired to I.S. Barriers.

Since the unit is being treated like its in a C1D1 Area customer is wanting to put seals at instruments also. I don't see this as being needed per

NEC 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

Am I correct?

RE: Seals in Class 1 Div1

Hi shocky1,

It depends on what's inside your C1D1-rated instruments.  If they truly meet the limits implied in 501.15(A)(1)(1), no seal needed.  Should be no seal needed for IS stuff either.

HOWEVER, check with the AHJ.  His or her word is final.  And don't forget the seals at the boundary by the safe area.

Good on ya,

Goober Dave

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