501.10(A)(3) 501.15(A)(1) Factory Sealed PB Control Stations - Class I, Division 1

[Dale001289]

Art 501.10(A)(3) states "All boxes and fittings shall be approved for Class I, Division 1"
To me, this means Nema 7 construction or equivalent.

Art 501.15(A)(1) Exception states basically conduit seals shall not be required entering enclosures where the switch, CB, fuse etc, is enclosed within a factory sealed explosionproof chamber located within the enclosure.

Therefore as long as the enclosure is explosionproof (e.g. Nema 7) in this case, a start-stop pushbutton control station, and contains has a factory sealed contact block, a conduit seal is NOT required.

Please confirm.

 

[rbalex]

Your conclusion is correct, but you should review the definition of approved in Article 100. There are other protection techniques in Section 500.7 that are suitable [Section 500.8(A)] for Division 1 but are not necessarily explosionproof.

 

[Dale001289]

Your conclusion is correct, but you should review the definition of approved in Article 100. There are other protection techniques in Section 500.7 that are suitable [Section 500.8(A)] for Division 1 but are not necessarily explosionproof.

Will do, thanks Bob!