Electricians: How to run grounding cable from panel out to grounding rod?

[phUnk]

What's the word on getting the grounding cable out of the subpanel, through the (detached) garage wall and into the ground? Should it be flexible metallic conduit from the panel until it hits the ground, at which point it should go bare?

Thanks.

[L7]

Not an electrician and not in Utah, but mine is a bare braided copper wire that runs from the panel and connects to the water pipe.

[Eldo]

If we give you some advice and later on your garage burns down to the ground, will you be upset?

(No reason, just wondering.)

[L7]

Worse still if the power fails, disabling the alarm (or booby trap) when the fucking fucks come back for the latest bike.

[Crass3000]

I just ran my garage subpanel ground back to the main ground at the main fuse box using 6-3 which has a ground. Not sure if thats the best way but it certainly is not atypical. Normally you don't tie the nuetral and the ground together at the subpanel, and then you run the ground and nuetral back to the main house panel seperately. They are then both tied to the nuetral/ground bar in the main fuse panel.

I am no electrician though but the information I found on the net indicated that this is normally how its done.

Edit: I guess I can't see anything wrong with grounding close to the subpanel as it would be a shorter route to true ground but you don't need to do that. I initially didn't see that you were in a detached garage so maybe grounding close to the subpanel might be best.

[bagtagley]

Go buy a Time/Life book cheapie.

[phUnk]

Go buy a Time/Life book cheapie.

Ignignokt: "Err, Innuendo."

Err: "Innurendo!"

[phUnk]

Note: I love how people skim a technical thread and post a response.

Waterpipe guy: You got a lot of waterpipes in your detached garage?

Didn't answer the question guy: That was a lot of buildup for "I wasn't paying attention and I don't know."


Now, if you'll excuse me, I'm off to beat bagtagley with the my two wiring books that also don't answer my question.

I LOVE YOU ALL!

[L7]

Waterpipe guy: You got a lot of waterpipes in your detached garage?

Smartass guy: Did you skim the part where I simply told you my setup? I guess I could have said 'attached to metal object extending into ground nearby to electrical panel' but waterpipe is easier and happens to be what it is. Just trying to offer what I've got to help. Feel free to shove the info up your ass along with the cheap time life book if you ever buy it.

[MrZach]

Phunk - you can have only one point in your home where your grounded conductor is bonded to earth. generally, if you're running a subpanel, would run a multi-conductor cable from your main panel that already has a ground in it - if this is not the case, you'll need to run an appropriately-sized grounding conductor from your subpanel back to you main panel or service entrance (whichever is easier). Point is - you do not want to ground your subpanel separately from the rest of your electrical system.

[Snow Dog]

Normally you run bare wire (of the appropriate guage) to grounding rods (of the appropriate length). Exposed wire should be protected with metal or plastic pipe.

I have this feeling that the grounding rods have to be wired together too so that the two panels (main and sub) share the same ground. My main (barn) and sub (house) have two ground wires each. I assume it's one to a ground rod and one between the panels (I'm not digging up the concrete to find out).

[phUnk]

L7: Thanks for the description of your set up. It doesn't answer my question, so I won't be sticking it up my ass, thanks. My subpanel is inside, as all subpanels are. Therefore, I need to know how to get it from the inside , to the outside and into the ground. Your post doesn't really address a single one of those points as they relate to my setup, I think you'll agree.

MrZach: The inspector, along with my unreachable sin-law electricians, have said explicitly that I need to ground the subpanel on its own: i.e. the ground wire from the feeder cable feeding the entire garage in not sufficient. So, it has to be panel in house -> feeder to garage subpanel -> #6 bare copper from the subpanel ground bar -> buried grounding rod #1 -> bare copper continuing to buried grounding rod #2 at least 8 feet away from the other rod.

And I'm tired of fucking working on this wiring with a fucking headlamp in the dark in the fucking cold at night after fucking work and I can't wait to find out how deep the fucking ground is fucking frozen but none of that is making me fucking cranky you can fucking bet on it.

[MrZach]

Curious - I'd have to have a discussion with your inspecor on that one (mention ground loop if you want to be a hoser). At any rate, if that's what he wants: There are stipulations for grounding separate buildings, though, (since their specific 'earth' ground isnd directly bonded to your service). Normally, you would bond the re-bar in the concrete of your garage to the ground in the subpanel since your home and garage aren't connented. If the inspector wants an actual earth ground installed, #6 bare copper to a ground rod close to the subpanel should suffice. If your gagare panel had its very own service, I would run a #6 copper from the panel through the wall (assuming an exterior wall) to a gound rod driven close to the location of the panel, then bond any water service in the garage to the ground bad in the panel as well. The grounding conductor does not have to be in conduit as long as its inside of a wall and exposed for minimal distances "not likely to incur damage from normal use of the area". If you have to run the ground wire alond a driveway or other similar area, it'll have to be in conduit to protect it from damage. I don't understand the requirements for two ground rods at all. Hopefully this helps more than hinders.

[phUnk]

MrZach, thanks for explaining further. I will dig around the edge of the slab and see if there is any exposed rebar to work with. The garage was built by the shittiest contractor I have ever worked with, "A-shed," and it's unlikely that they left any provision for grounding through the rebar. (This despite the fact that most two car garages with 16' doors are going to eventually have an opener installed.)

The garage panel will get power from a 50A 240V feeder cable that used to feed a hottub in the backyard. It's a 8/3 in conduit, so I'll have to carefully cut the conduit open in the middle of the yard, then dig a new trench and lay conduit for the 90* turn towards the garage.

Based on your description, it sounds like I should run the #6 copper through flexible conduit down from the panel (because this is an unfinished garage,) through the wall, down the outside of the garage exterior, then stop the flexible conduit once the wire is underground, then (obviously) run it bare to the first ground rod.

I'll go with that. I guess it'll be easy enough to change if it fails inspection. *shrug*

Oh, and the two ground rod requirement is just a lazy way to get around trying to prove less than 25 ohms resistance from your single ground rod. If you have two or more ground rods wired together, you don't need to pay anyone (or buy the tester) to do the resistance test.

Thanks everyone. Even L7,

[Crass3000]

The inspector, along with my unreachable sin-law electricians, have said explicitly that I need to ground the subpanel on its own:

If your going to the trouble of getting a permit and having an inspector why don't you just ask the inspector? If you can't get in touch with him then just wait till he gets back to you or call your state inspector. He's going to be the one to tell you if what you did is OK. It really doesn't matter what any of us think as he's the anal bastard thats going to give you problems.

[phUnk]

If your going to the trouble of getting a permit and having an inspector why don't you just ask the inspector? If you can't get in touch with him then just wait till he gets back to you or call your state inspector. He's going to be the one to tell you if what you did is OK. It really doesn't matter what any of us think as he's the anal bastard thats going to give you problems.

Good question: I was hoping to get a definitive answer here to avoid calling the inspector again. I don't want to annoy the guy until he just condemns my whole house and blocks my cell number.

[PaganSkier]

Sink that 8Ft ground rod completely below grade. Make sure it goes through your sprinkler system lines, gas pipe, sewer, and everything else you want grounded (think before you sink).

The grounding electrode conductor (GEC) should be #6 bare Cu or larger, and attach it to the grounding bus bar inside your subpanel. Run the copper through a small hole in the wall, and attach it to the contour of the building using proper staples. Conduit is not required.

Attach the #6 to the ground clamp, and you are bonded, grounded... Make sure that your GEC run is not subject to physical damage, like where you have your 5 pit bulls tied up.

Now as far as bonding the garage subpanel ground bus to the neutral bus, you only make the bond if you don't have an EGC or a continuous metal path between the buildings. Otherwise you will establish a ground loop which can cause some strange things to go down.

[phUnk]

You're the man now, RipDog.

[Buzzworthy]

Reading that hurt my brain just now. But of course I am at my old college and acting like a 22 year old. Wait.....um, nevermind. Freaking keg stand tonigt.