NEC Article 708.10(C) requires critical feeder circuits to be in RMC/IMC and have a 1-hour fire rating. I can't say I've ever seen such a beast. Are they sold commercially? What do they look like? I've got this mental image of putting pipe lagging on conduit, but I'm not so sure that would be enough. Do we have to start building insulated drywall boxes around conduit runs?
... and then 708.14 requires the same for thermostat wiring, phone wire and pretty much all critical communications circuits. I don't think those guys are going to be happy when their cable tray becomes drywall-encased RMC.
- before anyone gets too excited, 708 is "Critical Operations Power Systems", new in NEC 2008, and only applies to homeland security/military/emergency services type stuff.
