Hello all,
I was referred to this forum by someone on another forum with my questions about acceptable cable use in a temporary install. There has been some discussion between all of us involved, and I thought those who REALLY knew the code could give me some fodder for our discussions.
I am installing a fairly large theatrical-type lighting system on ground-supported truss for an exhibit which will last a few months in a building. Everything involved in this question and discussion is on this truss, not wired into the building or anything.
For the most part, all of the cable used to run the various lighting instruments is 12/3awg cable, I think SJOOW, with 15A parallel-blade (also called Edison in the theatre world) connectors. In some places, we have a power strip in which a few 30w (yes, thirty watt) lighting fixtures are plugged. Each of these is also fed by a 12/3 awg cable. However, in some locations, I have a single 30 watt fixture that may be about 10' from the power strip, thus needing a short extension.
I thought, since the fixture itself is built with 18/3 cable as it's source, that I should be able to use a 16/3 extension to connect this fixture, cutting down on cable cost and size/weight/etc. It seems silly to me to run a super-thick 12awg cable to power 30 watts. But some people have said that no matter what the end load, that every single cable should be 12/3 for such an install.
If I was running cable for something where fixtures would be changing or moving, then certainly I would make every cable 12awg, but this is set for this exhibit, then gets pulled out completely.
Since what I deal with is generally temporary installs in production (theatre/corporate/concert) situations, we don't always have formal training on real code (not looking to debate the pros and cons of this...I agree we should). Therefore, while I know that everything is perfectly safe and that all of our cable and connectors are thoroughly rated for the loads we are using, I can't vouch for whether something is directly covered by code or not.
I just want to have answers or change plans if needed before we get an electrical inspection.
Can anyone answer the above question for me? The lines really start to get blurry when we talk of temporary vs. permanent installs.
Thanks!
Sam R.
