Cabling for subpanel

[borisf]

I'm going to finish my basement over the next few months and need to add a subpanel as the main 40-slot box is almost full. I'm going to add a 125A 12-slot/24-circuit box directly underneath the main one and connect them with 2-2-2-4 copper. Since the subpanel will be directly beneath the main, my plan is to just use the center knockouts connected by a 2 inch-sized metal conduit nipple with locknuts in each box.

Question: do need I need to clamp the actual conductors as they enter each panel as I would with Romex?

Thanks in advance!

 

[Reach4]

No.

I think I would buy THHN wire by the foot, unless I had wire already.

 

[Sponsor]

 

[borisf]

Thanks for letting me know re: clamping.

They actually had the 2-2-2-4 copper at HD at just over $5/ft. It was cheaper and I figured I could always split out the conductors from the main sheath and so that's my plan.

 

[Jadnashua]

Sometimes, the wires in a sheath are not individually labeled, which isn't to code, I think, but not positive.

 

[Jadnashua]

Sometimes, the wires in a sheath are not individually labeled, which isn't to code, I think, but not positive.

 

[borisf]

The insulation on the individual conductors was color coded inside the sheath -- so I'm good there. Unfortunately, I wasn't paying close enough attention and while the conductors were 2ga (stranded copper), the ground was an 8ga or 10ga. Certainly not 4ga as I expected... Oh, well. One more trip to HD and now the job is done (see attached). Thanks all.

 

[Jadnashua]

It's not the color coding...it's that the wires themselves are marked with the type and gauge. On a cable, that's on the plastic sheath, and usually not on the individual wires.

 

[borisf]

Yup, the cables are colored but aren't marked individually. I passed inspection this morning, though. The inspector didn't care that they weren't labeled, just that they were large enough for the amperage. So, as far as the city of Seattle is concerned, all is good.

 

[Speedy Petey]

The insulation on the individual conductors was color coded inside the sheath -- so I'm good there. Unfortunately, I wasn't paying close enough attention and while the conductors were 2ga (stranded copper), the ground was an 8ga or 10ga. Certainly not 4ga as I expected... Oh, well. One more trip to HD and now the job is done (see attached). Thanks all.

You did NOT need to get a larger ground. #8cu is an appropriate sized grounding conductor for a 100A feeder.

Personally I'd have used just the cable with two SER cable connectors in the panels (the nipple was overkill) and placed the new panel next to the existing one.

 

[Jadnashua]

Keep in mind that ground is a redundant safety path to help ensure that the breakers or fuses will trip...it should NEVER see current on it otherwise, and if it does, it won't be there for long. That's why it can be smaller gauge than the normal, current carrying leads.