Non-TC Rated Cable in a Cable Tray

[weressl]

Sorry for not getting back sooner. Single conductor building wires had ICEA/IPCEA, UL, IEEE and/or NEMA "flame test" requirements for ages. The vertical tests were introduced when "cable support" systems became "cable tray" installations and started becoming recognized beyond "industrial" applications, especially multistory commercial. As usual, more constraints than necessary were added to make it "safer" not just safe. The tests were designed primarily for multiconductor PVC jacketed systems.

I have no problem drawing the line between "safe" and "unsafe" and pretty much ignoring the dollars. But when a Proposal to make something "safer" is made, it should also be justified economically.

I beleve that the 'elevated' flame test requirements was due to the fact that there will be masses of cables together in an open installation, eg. not in an enclosed raceway, where plain oxygen starvation would really make a fire difficult to sustain. In this case an engineer may make qualified evaluation, but that may not be available in all times.

I absolutely agree with the value judgment approach. If that would be our guiding principles would NFPA 70E exist as it is today?