NEC 501.15 B(2) Class 1 Div 2 Boundary Seal-off - exception 2 & 4

vds002

New User
Location
TN
Occupation
EE
Would like to get a discussion going on C1 D2 boundary seal-off in outdoor installation.

In our application we are going from Ex-Proof Instrument (outdoor open area) to a Non-Ex-Proof Enclosure with terminals in C1D2 area (outdoor open area). Then we are going from a Non Ex-Proof Enclosure to Control panel via underground sleeve with gutter boxes at both ends.

As per NEC 501.15 B (1), the instrument is considered explosion proof enclosure and will need seal-off at instrument within 18 inch.

However for the C1D2 boundary there are items in Exception 2 and 4 that apply to our installation eliminating the need for boundary seals.

Please see below screen shot from code.


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