Legal Chase for Portable Cables + Company Switch Questions

[click]

I’m designing a production taking place in a church basement gymnasium. This will be the first theatrical production to happen in the space.

There is ample power available, although the existing switches are in an electrical room which is not near the performance area. The existing installation contains (1) spare (unused) 100-Amp 3-phase breaker plus (2) spare 60-Amp 3-phase breakers. We hope to use one 60-Amp for audio, and the rest of the power for lighting.

Between the electrical room and the gymnasium is a storage room. This room (masonry construction) has sprinklers. This would seem an ideal location for portable dimmer packs. The church is amenable to doing the appropriate electrical work (licensed electrician) to install a few company switches (i.e., Lex Products with Cam-Lok outputs) in this storage room which would extend the available power from the electrical room.

My questions:

1. I need to specify a completely legal way for portable multicables to pass from the dimmer racks in the storage room to the performance area through a masonry wall. This would be akin to sending cables through a “mouse hole” in the proscenium of a theatre, I presume. I’ve seen fire-rated metal access doors (12” square) which would preserve the integrity of the masonry wall when the door was closed. When the door is open to pass the portable cables, I understand I might use fire-stop pillows to pack the space around the cables in the opening.

In a thread called “NEC Code Applicability,” Steve Terry wrote:

Portable cables can penetrate walls, floors, or ceilings through approved "pass-through" chases. (a mouse-hole that was not fire-stopped would no doubt be a stretch).

What exactly is an “approved pass-through chase?”

I need to know if this idea is viable and legal, and if so if there is a recommended manufacturer and model for the pass-through chase hardware. By the way, this is in New York City.

2. What height would be appropriate for the pass-through chases? Floor level seems a trip hazard. The cables will mostly be running up the wall (i.e., along a boom or taildown) to rigged pipes at +16’-0”; the storage room ceiling at 7’-0” limits locating the chase at grid level.

3. Are there rules or restrictions governing the height and/or location of installed company switches?

4. Are there other factors I need to consider?

Any advice is most appreciated.

 

[MisterTim]

I don't know much about the legal issues, but I'll tell you that it is VERY helpful to have both a pass-through at floor level and above head level. We almost always use both; feeder on the bottom and data/audio on the top running back through a cable tray to FoH.

 

[STEVETERRY]

I’m designing a production taking place in a church basement gymnasium. This will be the first theatrical production to happen in the space.

There is ample power available, although the existing switches are in an electrical room which is not near the performance area. The existing installation contains (1) spare (unused) 100-Amp 3-phase breaker plus (2) spare 60-Amp 3-phase breakers. We hope to use one 60-Amp for audio, and the rest of the power for lighting.

Between the electrical room and the gymnasium is a storage room. This room (masonry construction) has sprinklers. This would seem an ideal location for portable dimmer packs. The church is amenable to doing the appropriate electrical work (licensed electrician) to install a few company switches (i.e., Lex Products with Cam-Lok outputs) in this storage room which would extend the available power from the electrical room.

My questions:

1. I need to specify a completely legal way for portable multicables to pass from the dimmer racks in the storage room to the performance area through a masonry wall. This would be akin to sending cables through a “mouse hole” in the proscenium of a theatre, I presume. I’ve seen fire-rated metal access doors (12” square) which would preserve the integrity of the masonry wall when the door was closed. When the door is open to pass the portable cables, I understand I might use fire-stop pillows to pack the space around the cables in the opening.

In a thread called “NEC Code Applicability,” Steve Terry wrote:

Portable cables can penetrate walls, floors, or ceilings through approved "pass-through" chases. (a mouse-hole that was not fire-stopped would no doubt be a stretch).

What exactly is an “approved pass-through chase?”

I need to know if this idea is viable and legal, and if so if there is a recommended manufacturer and model for the pass-through chase hardware. By the way, this is in New York City.

2. What height would be appropriate for the pass-through chases? Floor level seems a trip hazard. The cables will mostly be running up the wall (i.e., along a boom or taildown) to rigged pipes at +16’-0”; the storage room ceiling at 7’-0” limits locating the chase at grid level.

3. Are there rules or restrictions governing the height and/or location of installed company switches?

4. Are there other factors I need to consider?

Any advice is most appreciated.

An "approved pass-through chase" is one that the AHJ says is OK. I suggest that a piece of 4" or 6" rigid conduit (or multiple conduits) with chase nipples at either end would be a good start.

ST

 

[avkid]

The company switch installation would follow the same regulations as any other disconnect.

 

[mstaylor]

The company switch installation would follow the same regulations as any other disconnect.

He's not worried about the company switch, he is worried about the soco coming to the dimmers, I believe.

 

[tjrobb]

First, you will want/need a penetration designed for frequent addition and removal of cables. Something in this arena, again note how the cables can be added or removed as needed. This could be used for switch to dimmer or dimmer soco cables as needed.
Second, standard "working space around electrical equipment" rules apply in regards to company switches. 6'-6" of headroom, 30" or width of equipment wide, and 3' from the face of the equipment (at 120V, add 6" for 277/480).
Lastly, I worked in a theatre that used a beefed-up Z-bracket (think angle bracket with added upright to hold cable) to go around doors; this is a poor description and I hope you get the idea. Could be a good way to route cables along the wall.
I AM NOT a licensed electrician, nor do I know the quirks of the NY codes, but I hope this gets you started.

 

[venuetech]

the facility i work at has short 6" ID pipes installed. each side has threads and a cap is normally in place until the chase is needed.

 

[click]

Second, standard "working space around electrical equipment" rules apply in regards to company switches. 6'-6" of headroom, 30" or width of equipment wide, and 3' from the face of the equipment (at 120V, add 6" for 277/480).

Can you let me know where you found this information? Is this the NEC? This is quite useful, and I'd like to read more. Thanks.

 

[click]

the facility i work at has short 6" ID pipes installed. each side has threads and a cap is normally in place until the chase is needed.

Might you be able to upload a photo of these pipes? This will help in explaining the concept to the contractor. Many thanks.

 

[journeymanjohn]

I beleive he would be refering to Rigid Galvanized Conduit, of the 6" variety, which is the largest standard size made. Typically sold in 10' lengths, however you can probably get nipples made form any contractor that is set up to industrial work. It's the same stuff you see at lowes or home depot in 1/2, thru 1 1/4". Your local electrical supply house could probably have it made, or recommend who to go to. Of course, you might consider going with smaller diameter conduit, and just adding more of them. Maybe some 4" RGC.

 

[epimetheus]

I feel it important to note that if you're routing single conductor feeder cable through metallic conduit, even if it's only short nipples, you should always route all phase, neutral and ground conductors through the same conduit. If you were to have A phase in one conduit and B & C phases in another conduit, for example, you'd have inductive heating problems with ferrous conduit. Very bad.

 

[tjrobb]

That segment comes from article 110, section II. Special requirements are in 520 for theatres and places of assembly (518 applies to a limited degree, but mostly to smaller spaces). NFPA - you may need to create an account for access.

 

[venuetech]

the facility i work at has short 6" ID pipes installed. each side has threads and a cap is normally in place until the chase is needed.

correction: one side has threads/cap the other side is cut clean, looks like normal black pipe to me. not rigid conduit.

The pipe must have a solid bracket welded to it as it is very solidly installed within the framed walls. extending only one inch on the cut side and about 3 inches on the threaded side.

I will try to get some photos later today.

 

[derekleffew]

Would the term "multi cable transit" be appropriate here, or does that only apply to floating vessels?

 

[venuetech]

Photos to post

 

[Chris15]

I have seen a similar sort of conduiting arrangement done with non metallic conduit. To me that makes more sense as you avoid the effects of ferrous conduit epimetheus spoke of. I would also expect it be gentle on the cables, metal snares bad things happen to the cable, plastic snares, plastic loses. A conduit is probably going to be cheaper than a new multicable...

 

[derekleffew]

Three six-inch conduits, used for power and telecom to TV trucks.



It seems the https://www.raincap.net/home covers are re-purposed from another industry. Better than a gaping hole in the exterior wall, but not by much.

 

[STEVETERRY]

Three six-inch conduits, used for power and telecom to TV trucks.

View attachment 4692 View attachment 4693

It seems the Raincap Industries - The Raincap covers are re-purposed from another industry. Better than a gaping hole in the exterior wall, but not by much.

Even assuming extra-hard usage cable going though the chase, I don't like the idea of a raw threaded conduit edge. One way or another, there needs to be some sort of chase bushing on the end of the pipe.


Conduit & Fittings | Conduit Reducing Bushings and Washers | Plastic Bushing 2" Trade Size | B218111 - GlobalIndustrial.com

 

[jstandfast]

Even assuming extra-hard usage cable going though the chase, I don't like the idea of a raw threaded conduit edge. One way or another, there needs to be some sort of chase bushing on the end of the pipe.


Conduit & Fittings | Conduit Reducing Bushings and Washers | Plastic Bushing 2" Trade Size | B218111 - GlobalIndustrial.com

Concur. Big time.

 

[venuetech]

perhaps the electricians should borrow a burlap bag or two from the riggers to temporarily soften the edges. That or the fire bags can be arranged so the chase edges are not in contact with the cable. In any case the electrician should spend some time inspecting the cable run and taking any appropriate action necessary. both before the run is made and after.