panel ground minor detail

[billconner]

I have a under ground for a sub panel in a detached building. It's an Uber, no. 4 copper, rising to panel through block cores and then less than a foot to panel.

Should I run it through a knockout with a 2 screw (Romex) clamp, a bushing, or bare? Seems no clear code language.

 

[Dagny]

that or a 1/4 inch hole

 

[sparky 1971]

There should be factory 1/4"ish holes top and bottom on each side of the center knockout. I use these but you can do it however you want.

 

[FirstGen]

That's a great detail for us 'over-thinkers'!

I am at the same point and was going to use a 2-Screw Romex clamp if it will tighten onto my #6 bare copper that runs to my ground rods. I'm sure I can get creative and configure it to tighten. It just feels like it should be mechanically secured at the panel in case something like a mower were to snag it outside the building.

 

[Norcal]

That's a great detail for us 'over-thinkers'!

I am at the same point and was going to use a 2-Screw Romex clamp if it will tighten onto my #6 bare copper that runs to my ground rods. I'm sure I can get creative and configure it to tighten. It just feels like it should be mechanically secured at the panel in case something like a mower were to snag it outside the building.

You need to protect it so that does not happen.

 

[billconner]

I used a Romex clamp and seemed to grip fine. Also for me not much risk of strain as it's s ufer and comes through a grouted wall less than a foot below panel.

 

[exranger06]

Kenny clamp is specifically made for this:
https://www.morrisproducts.com/images/15390-15399-Spec.pdf

 

[billconner]

Kenny clamp is specifically made for this:
https://www.morrisproducts.com/images/15390-15399-Spec.pdf

Neat! Just this or do you still connect it to ground bus?

 

[FirstGen]

Kenny clamp is specifically made for this:
https://www.morrisproducts.com/images/15390-15399-Spec.pdf

That's perfect! Thank you!

 

[yatg]

Thanks for your support!

 

[billconner]

So, another project ahead. Romex (and some pricey vapor barrier plastic boxes.)

I'm planning 1 - 15 amp circuit. Maybe I'll go 20. Probably 6 or 7 receptacles and 8 sconces, LED of course. (There's a second circuit in the room, existing, so not that thin.)

Can I reuse white 12 guage NM for 20 amp circuits? It's imprinted and in good shape. All wiring in stick frame walls with fibreglass.

Can I use it for 15 amp circuit?

Probably I'll ask inspector but wanted a heads up.

 

[mike93lx]

NM and not nm-b? I am pretty sure that is no if you are talking about a "new" install.

 

[rlitman]

NM and not nm-b? I am pretty sure that is no if you are talking about a "new" install.

Agreed. If it's old NM, scrap it. If it's white, but NM-B, that's fine.

 

[billconner]

I'll look at what is embossed on it. This was all 1994 or later. From Google it seems the yellow was introduced in 2001.

Thank you!

 

[mike93lx]

I'll look at what is embossed on it. This was all 1994 or later. From Google it seems the yellow was introduced in 2001.

Thank you!

There is lots of white #12 nm-b out there

94 would mean nm-b, unless it was old stock and someone that didn't care

 

[rlitman]

I'll look at what is embossed on it. This was all 1994 or later. From Google it seems the yellow was introduced in 2001.

Thank you!

As I understand it, Southwire Romex (the brand), started the white/yellow/orange color coding to differentiate themselves, and when it caught on and inspectors demanded it, other brands changed too (Cerro, Carol, etc.). It looks like Cerro is using purple for 12/3 now. Really, any color other than green would likely be acceptable, and I'd expect more color changes in the future.

There's nothing special about the white vs yellow for your purposes. Color coding just makes installation and inspections easier, but that dash B is itself important.