Grounding question

[chrisa28]

Hi there, I've gotten a lot of great info and tips from this forum so thanks in advance! I have a question about electrical grounding. I'm wiring up a new workshop (and rewiring some old garage electrical that was overloading a circuit. Here are the basics:

1) have a 100 amp subpanel in garage.

2) ran 1 1/4" EMT conduit straight up into attic so that I can easily run Romex directly to the tools from the attic without conduit all over the walls and ceiling.

3) The 1 1/4" conduit from the panel terminates in a very large junction box (10x10 I think) in the attic so that I have plenty of room to work.

4) I'd like to try to run all my grounds for the various circuits to the attic junction box, then a single ground down to the panel to save space. Everything in that junction box is 12 gauge wire. I was going to run a single 8 gauge ground wire from the panel to the junction box, then tie in the 6 or so ground wires (12 gauge) for the various circuits to the main 8 gauge ground wire in the junction (none of these are the 240v tools, i ran those as completely separate circuits/conduit with 12/2 romex and individual grounds). Everything is also grounded to the individual boxes along the way, just looking for that last connection down to the panel.

5) Assuming that is ok... what is the best way to connect those? I was trying to find something like a Wago or other larger gauge splicing connector so that I'm not trying to hold 5-6 THHN solid 12 gauge wires against a stranded 8 gauge wire with just a wire nut. Or is a wire nut the best way?

Thanks in advance for any help!!!
Chris

 

[Duece56]

Hi Chris,
I would install a ground bar (similar to the one in your panel) inside the 10" x 10" junction box and land all the grounds from the attic circuits onto that. Ground bar kits are available at the big home centers in different sizes. You'll want to connect the ground bar to the back of the junction box using 10-32 machine screws into threaded holes (code requirement). #10 drill-point screws work well for this. If you have 1-1/4" EMT between the panel and the junction box and all your set-screws and locknuts are tight, you don't actually need a separate grounding wire, but it certainly wouldn't hurt to run the #8 between the ground bar in your panel and the new ground bar in the junction box. You mentioned that the panel in the garage is a subpanel, so all of the grounds need to be separated from the neutrals in that panel, so be sure to bring your #8 to the ground bar and not the neutral bar.
Ed

 

[BigGarage]

 

[wyliesdiesels]

you dont need a #8. largest size ground wire you would need is based on largest breaker size. in this case #12

 

[chrisa28]

@Duece56 - that's an outstanding idea. So much simpler and I never would have thought of that.

@wyliesdiesels - ok, that was my original plan but a buddy said that technically if I ran that many circuits on one ground an inspector might tell me the ground to the main panel needs to be oversized in case more than one tripped at once... that the ground needed to be sized for more than the load of one circuit. This is my first time doing an entire rewire like this so I wasn't sure. Thanks for the comment - that will be much easier than working with #8!

 

[wyliesdiesels]

@wyliesdiesels - ok, that was my original plan but a buddy said that technically if I ran that many circuits on one ground an inspector might tell me the ground to the main panel needs to be oversized in case more than one tripped at once... that the ground needed to be sized for more than the load of one circuit. This is my first time doing an entire rewire like this so I wasn't sure. Thanks for the comment - that will be much easier than working with #8!

your buddy's advice is based on the urban legend code book. ask him for a reference in the NEC. and after that, dont ask him for advice again

 

[acer66]

your buddy's advice is based on the urban legend code book. ask him for a reference in the NEC. and after that, dont ask him for advice again

You might be not aware of it but they just came out with the revised and improved 2024 edition of the urban legend code book so his friend might be right you know.

 

[bronc076]

The nice thing about living in a rural community is urban legend code is not applicable!

 

[chrisa28]

your buddy's advice is based on the urban legend code book. ask him for a reference in the NEC. and after that, dont ask him for advice again

Ha! Indeed. His code book is more along the lines of "my uncle taught me to do it that way and I've been doing that for 40 years" with no regard to anything else

 

[PCustoms]

You might be not aware of it but they just came out with the revised and improved 2024 edition of the urban legend code book so his friend might be right you know.

You do know he's an electrician, right?


@chrisa28, are you using EMT from metal panel to metal box?

 

[acer66]

You do know he's an electrician, right?

Yes, that is why I posted it.

 

[chrisa28]

You do know he's an electrician, right?


@chrisa28, are you using EMT from metal panel to metal box?

@PCustoms Yes, EMT for everything. I'm pretty sure I had read on several other posts that you don't have to run a ground all the way back to the panel if every box is properly grounded, but it seems like most suggest doing that extra work if it's not too inconvenient. I don't have a lot of turns and bends, straight up from the panel and a big slow 90 out of the corner of the attic where it's easier to work with that big junction box. So I thought it was worth the extra few minutes to fish the ground with the other 12 gauge thhn. Was rolling right along until my urban legand buddy told me I needed to use that #8 and I got stuck on the connection issue! Glad yall were able to help out so fast. thanks again.

 

[Chuckster in NJ]

Ha! Indeed. His code book is more along the lines of "my uncle taught me to do it that way and I've been doing that for 40 years" with no regard to anything else

I would tell him: "You have been doing it wrong for 40 years"

 

[dave*99]

You might be not aware of it but they just came out with the revised and improved 2024 edition of the urban legend code book so his friend might be right you know.

Technically, the NEC is updated every 3 years, but the urban legend code book is continuously updated. It can change faster than you can type or talk.

 

[larry4406]

Technically, the NEC is updated every 3 years, but the urban legend code book is continuously updated. It can change faster than you can type or talk.

I think it can even change just by thinking about it; wishing will make it so.