방폭 시공 - Sealing Fitting(실링 피팅)과 방폭함 사이 거리
Sealing Fitting(실링 피팅)과 내압방폭기기 사이의 거리에 대해서 아래와 같이 NEC에 언급이 되어 있습니다. 해당 코드에서 규정하는 거리는 450 mm 입니다.
NEC(National Electrical Code),
NFPA(National Fire Protection Association) 70
Article 505 Zone 0, 1, and 2 Locations
505.16 Sealing and Drainage
(B) (2) (b) Conduit seals shall be installed within 450 mm (18 in.) from the enclosure. Only explosionproof unions, couplings, reducers, elbows, capped elbows, and conduit bodies similar to L, T, and cross types that are not larger than the trade size of the conduit shall be permitted between the sealing fitting and the explosionproof enclosure.
그런데 IEC(The International Electrotechnical Commission) 코드에서는 50 mm로 규정하고 있습니다. 두 코드가 다르지만, IEC 60079-14을 기준으로 작성된 KS C IEC 60079-14가 국내 표준이라, IEC 기준을 준수하는 것이 좋을 것 같습니다.
IEC 60079-14 Electrical installations design, selection and erection
14 Additional requirements for type of protection “d” – Flameproof enclosures
14.4 Conduit systems
The distance from the face of the seal closest to the enclosure (or intended end-use enclosure), and the outside wall of the enclosure (or intended end-use enclosure) should be as small as practical, but in no case more than the size of the conduit or 50 mm, whichever is the lesser.