Installation of Conductors with Other Systems: NEC Article 300.8
Can anyone advise on correct segregation of wiring/tubing..I am installing older process system with PLC-5 system that uses penumatic tubing, 24VDC and 4-20ma signals...can these all go in same conduit or is that bad practice..?
It is bad practice. In general the National Electric Code prohibts non-electrical conductors in electrical raceways. Electrical raceways are defined in
Article 100 Raceways as "an enclosed channel of metal or non-metallic materials designed
expressly for holding wires, cables, or bus-bars, with additional functions as permitted in this Code.
Raceways include, but are not limited to, rigid metal conduit, rigid non-mnetallic conduict, intermediate metal conduit, liquidtight flewible conduit, flexible metallic tubing, flexible metal conduit, eleectrical nonmetallic tubing, electrical metallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wireways, and busways."
Although cable trays are not considered to be raceways, the permitted uses for cable trays do not include non-electrical items.
EDIT: No, I was wrong. There is a specific prohibition in
NEC Article 300.8 Wiring Methods. Installation of Conductors with Other Systems:
"Raceways or cable trays containing electric conductors shall not contain any pipe, tube, or equal for steam, water, air, gas, drainage, or any type of service other than electrical".
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