Theaters NEC520

[Jessebrgmn]

Stage Lighting Hoist use flexible SC cables to move up and down with motors. Now the same lights, on the same mounting bracket, on the same stage, however they are hanging on chain with no motors, should they use SC cable or should they be considered fixed and use EMT? We used SC on chain because there are many moving lights and curtains around these lights and they will experience movement sooner or later, we have passed inspections with this argument, however we have recently failed and were told to use EMT and all thread. I haven't found anything on this in the NEC and think it falls under checking with each local inspector, thoughts?

 

[iwire]

It is not up to the inspector to tell you how to mount the lights.

That said if they are chain hung I would use a flexible raceway or cable from chapter 3.

 

[mgookin]

I would argue the lights on motors are intended to be moved during a live performance and the lights on chains are intended to be moved between shows/ acts/ scenes and are therefore still intended to be moved on a regular basis.

 

[gadfly56]

Theater lighting is the essence of temporary lighting. SC should be fine for any installation, although you may want to be careful of bundling too much of it together. There is no time limit regarding temporary in this application; a luminaire could stay in one spot for 40 years.

 

[mgookin]

PS: Welcome to the forum!

 

[gadfly56]

Well aren't I the rude dude? :slaphead:

Yes, welcome to the Forum.

 

[zbang]

the lights on chains are intended to be moved between shows/ acts/ scenes and are therefore still intended to be moved on a regular basis.

Seconded (or third-ed?). Lights very seldom move during a performance but that doesn't make them "fixed" in the sense of the NEC. And, if the mounting bars are hung with all-thread, they will move, and non-flexible conduit will come loose. Seen that too often.

(Welcome)

 

[iwire]

The fact the OP proposed using EMT suggests to me these lights are not being moved.

But hey, maybe they make plugs for EMT.

 

[mgookin]

Stage Lighting Hoist use flexible SC cables to move up and down with motors.

Now the same lights, on the same mounting bracket, on the same stage, however they are hanging on chain with no motors,

should they use SC cable or should they be considered fixed and use EMT?

We used SC on chain because there are many moving lights and curtains around these lights and they will experience movement sooner or later,

we have passed inspections with this argument, however we have recently failed and were told to use EMT and all thread.

I haven't found anything on this in the NEC and think it falls under checking with each local inspector, thoughts?

Seems he expects them to move.
He was questioning if he should use emt; he was not proposing it.

Is hanging on chain "fixed"? I say no. It can move laterally (two axis') and even on the third axis it can go up with a force only slightly greater than the weight of the fixture.
Using emt means that emt is going to be subject to damage.

 

[gadfly56]

It just occurred to me to wonder if these are work lights. Such fixtures rarely if ever move and are meant to provide illumination during rehearsals, crew calls, auditions, etc. I could see an argument being made that that type of fixture should be more permanently mounted. Not saying I agree they must be, but I can see where the inspector is coming from.

 

[iwire]

First off let me say I have not said cord would not be acceptable

I can chain hang an 8' fixture in an office space and supply it with cord. This applies to anywhere.

The reason I suggested a chapter 3 flexable wiring method is due to the fact the OP suggested EMT which to me is the wrong choice for chain hung fixtures.