Securing Cable from Conduit

[ABusDriver]

Expert Sparky's,

I've made progress getting my previously flush mounted box switched to a surface mount. I used 1/2 inch plywood secured to the studs and mounted to subpanel to the plywood. I used a 2" conduit (secured with 4 clamps) from the panel to about 8" above where the ceiling sheetrock will go. In a previous thread it was mentioned that the conduit should terminate in a large junction box and the cables would leave the box to the various circuits. I'll probably have 6 or 7 cables (12-2 size) from the panel.

Is a junction box required or is it ok to secure the cables to the plywood with staples within a certain distance from exiting the cable? Looking at 300.15 C of the code it looks like a box isn't required as long as there is abrasion protection, which I have. I couldn't find a minimum required distance for fastening the cable in the code. Is it 12" from exiting the conduit?

Another question I have is about running cables together through the same stud hole from one outlet to the next. I've run the cable (12-2) from the panel to outlet box #1. I'd like to run a cable from outlet box #1 to outlet box #3 in order to alternate the power source (breaker) on adjacent outlet boxes. Since this will require running 2 cables together through the same stud holes for about 32" will there be any change to the ampacity rating? I know I've read about de-rating for 24" or more when cables run together but I'm not sure it applies in this case.

Thanks for your help.

George

 

[Zeke]

This will probably help.

 

[AntonLargiader]

There are conduit-to-NM clamps. They look exactly as you would expect them to look. Sort of like a duck bill.

 

[AntonLargiader]

Just realized that didn't really address your question. How do the cables leave the panel? Is the conduit attached to the panel, and the cables are routed into that and out the top before they are ever clamped? Or do the cables leave the panel through NM clamps and then go into the 2" PVC? If the former, I think you'll need something on top because otherwise the panel basically has a hole in it. It's like if the cables just exited the panel through a 2" hole rather than being clamped. If the latter, you're probably fine because the PVC isn't really serving as conduit; it's just protection like sheetrock would be, over cables that don't require conduit. I ran a similar idea past my inspector.

As for the bored holes in studs; I just went through this and my conclusion was that it's fine. There are people who disagree, but I think they are misapplying the concept of bundling.

 

[zmaxmotorsports]

Depends on where you're located,I'd normally seal the end of pipe with duct seal in end of pipe around wires.

 

[ABusDriver]

This will probably help.

Hmm...lots of opinions on whether romex can be used in conduit. My conduit runs from the subpanel to just above the ceiling. Is it a complete system or only for protection? Hmm...

 

[ABusDriver]

Just realized that didn't really address your question. How do the cables leave the panel? Is the conduit attached to the panel, and the cables are routed into that and out the top before they are ever clamped? Or do the cables leave the panel through NM clamps and then go into the 2" PVC? If the former, I think you'll need something on top because otherwise the panel basically has a hole in it. It's like if the cables just exited the panel through a 2" hole rather than being clamped. If the latter, you're probably fine because the PVC isn't really serving as conduit; it's just protection like sheetrock would be, over cables that don't require conduit. I ran a similar idea past my inspector.

As for the bored holes in studs; I just went through this and my conclusion was that it's fine. There are people who disagree, but I think they are misapplying the concept of bundling.

Thanks for the reply.

My current configuration is the former of your descriptions. The conduit is attached to the subpanel with a lock ring and bushing. The cable exits the subpanel, goes through the conduit, and exits just above the ceiling. I realize I need something to fix the cable in position, so I've stapled it to the plywood just after exiting the conduit. I can't find any specification (if one exists) as to how, or a distance from exiting the conduit, the clamping of the cable is required. I had originally planned to construct a raceway and exit the subpanel through the knockouts with NM claps and staples up the plywood. I thought the conduit looked cleaner and would be easier. I'll have to investigate the junction box and clamping method utilized exiting the box.

I've seen plenty of wiring in my house with two cable running through the same holes for some distance. I don't see any problem either, but the inspector is the final arbiter of course. In MN it's a state inspector.

 

[AntonLargiader]

I think 312.5 describes a lot of what you have in mind with the conduit. To me, it reads like it's OK as long as you comply with the (C) exception rules.

 

[ABusDriver]

I think 312.5 describes a lot of what you have in mind with the conduit. To me, it reads like it's OK as long as you comply with the (C) exception rules.

Thanks again for the reply.

I agree that 312.5 applies and with complying with all the exceptions. My question now is with exception C.2. It states that "The raceway extends directly above the enclosure and does not penetrate a structural ceiling." My garage is built with rafters and I plan on sheetrocking the ceiling once the wiring is complete. If the conduit extends into the space above the sheetrock does that violate the exception? It would seem silly to have the conduit end some distance below the ceiling.

 

[ABusDriver]

As a follow up for others in the same situation I called the state area rep and he said stapling the cable within 12" of exiting the conduit was acceptable. He also said to check the conduit fill capacity and the de-rate table for the number of cables in the conduit.

Work resumes!