Wire install into electrical box

[DavidDaMonkey]

I'm going to be installing some NL4 speaker jacks at a few locations around a new black box I'm working on. I wanted to run my thoughts by all of you and see if any red flags came up.

I will be using West Penn 226 to come off of a rack panel that will connect to my amps outputs. I want to run this up to the steel rafters that are about 18 inches above the pipe grid. I will screw j hooks into the rafters to support the wire. I will then screw a handy box with a speakon plate onto the rafter and connect the wire into there. I will drop down some speakon cable that will stay tied up to the pipe grid to get to various speaker locations.

Do I need any sort of conduit or sleeve going into the handy box or can I run the wire straight into it? Are there inherent issues with attaching to a steel rafter? Is it a bad idea to just support the cables with j hooks without using conduit for the entire run?

The rafter is not a surface that anyone will be clamping to or hanging from.

 

[Morte615]

If it's a permanent install then use conduit. Any national code I can think of says it would have to be in conduit if it is coming from the amp to the speaker (high voltage line). If it is just a signal line than I don't THINK it needs to be in a conduit.

If this is only a temporary install I would not bother with the junction box, just run the cable straight from the amps to the speakers.

 

[DavidDaMonkey]

If it's a permanent install then use conduit. Any national code I can think of says it would have to be in conduit if it is coming from the amp to the speaker (high voltage line). If it is just a signal line than I don't THINK it needs to be in a conduit.

If this is only a temporary install I would not bother with the junction box, just run the cable straight from the amps to the speakers.

It is a permanent install, but I'm trying to avoid running conduit if possible. I didn't realize speaker lines were considered high voltage. If that's the case, wouldn't the bare wire connections on the back amps be dangerous? What about just holding the end of a male 1/4" the wrong way?

To clarify: I'm not saying you're wrong, I'm just curious.

 

[museav]

Look at the back of the amps involved and they will usually indicate what wiring Class the output has to be considered. Some very high output amps do require the output wiring to be addressed as Class 1 wiring the same as AC power but most are Class 2 or 3.

Another potential issue is whether for installed cable your local code and/or AHJ will take exception to anything other than plenum rated cable being run exposed in a public assembly space.

Installed cable also has to not be subject to damage during normal building use. That is greatly a subjective determination by the AHJ but where they may deem it subject to damage it may have to be in conduit.

I also wasn't clear about the extension cables from the plates to the grid, but I think the AHJ may have a problem if those cables are there all the time rather than just when being used.

 

[BillConnerFASTC]

It is all up to the local authorities but usually if the cable is not in conduit, then it needs to be plenum rated.

 

[DavidDaMonkey]

Thanks for all the info. I will check on the class rating. It's a QSC PLX3102, but it will be a few days until I'm in the space again and can check it.

No work is ever done at the rafter level during normal building use, so I should be ok there.

I've also located the plenum version of the wire.

As far as the speakon cables coming from the connectors, I'm going to try to push for calling them temporary knowing that its easiest enough to remove if needed. I don't want my jacks mounted to the pipe grid because I know they would occasionally be in the way, and it takes some scaffolding that we don't normally use to reach the rafters, so I'd like to at least leave a tail hanging down for easier access. I'll look into other options just to be safe.

 

[teqniqal]

Black Box Theatres are inherently a rough-usage environment. I recommend installing conduit on that basis alone. We are sometimes too eager to junk-up our spaces. Remember that the audience can see these things and it subtly places the impression of sloppy work, 2nd-rate operation in their minds. Do it professionally and no one will think twice about it.

One note: Use back boxes for the input / output plates that are larger than the plates so you don't end-up having the sharp corners of plates overhanging the boxes. These lurk in the dark for the next person to reach-up and shred their flesh. Being a Black Box generally implies that the box, conduit, and cover plate will all be black, too. We don't need any more stealth vampires in the theatre plant. Resource: FSR SMWB - SMWB Series