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-   -   Ground rod and ground wire question (http://www.diychatroom.com/f18/ground-rod-ground-wire-question-112257/)

mulltron 07-28-2011 11:43 AM

Ground rod and ground wire question
 
Hi All!
Newbie here with questions.

I have a 240/120V subpanel in a shed and the run is about 60 feet to the main box 3 THHW #8 (2 -120V out of phase and neutral) and 1 THHW #10 (ground) from shed to main box through PVC from a 40A 240V breaker on the main box.

I am told I need a ground rod for the shed. Is one enough or do some subpanels need more than one? I have never bought or put in a ground rod before. What size should I get? Can I get them at home depot?

What kind of wire do I run to the ground rod?
Do I soldier the wire to the rod or can I connect with a clamp?
Do I run the wire from the ground rod and attach/screw it to the back of my subpanel box?

I also had a question about what the proper connections are for all the grounds that come from the subpanel circuits along with the ground wire that comes from the main box. Someone told me it was ok to put them on the neutral buzz bar (the one the white wires go to) and someone else told me to mount a new buzz bar to the subpanel box and connect all the grounds there. I need some advice to help me know the right thing to do. If I didn't provide enough info about my setup, or if I am off in anything I said please let me know.

Thanks for all of your help!

md2lgyk 07-28-2011 12:31 PM

You technically need two ground rods, at least 6 feet apart (not a pro, but I think that's the correct spacing). They come in different lengths, but I believe by code they must be driven at least 8 feet into the earth. The ground wires can be #10, and I believe they must be solid and bare. They are connected to the rods with a special clamp (called, oddly enough, a ground rod clamp). I doubt you'll find the rods at Home Depot, but you can probably buy them online if there's no "real" electrical supply company in your area.

You do NOT want the neutral and ground bonded (connected together) in the subpanel. You will need to have a separate ground bar - all ground wires will connect to it. Ground bar kits are cheap if your subpanel doesn't come with one.

electures 07-28-2011 01:16 PM

Quote:

Originally Posted by md2lgyk (Post 695486)
You technically need two ground rods, at least 6 feet apart (not a pro, but I think that's the correct spacing). They come in different lengths, but I believe by code they must be driven at least 8 feet into the earth. The ground wires can be #10, and I believe they must be solid and bare. They are connected to the rods with a special clamp (called, oddly enough, a ground rod clamp). I doubt you'll find the rods at Home Depot, but you can probably buy them online if there's no "real" electrical supply company in your area.

You do NOT want the neutral and ground bonded (connected together) in the subpanel. You will need to have a separate ground bar - all ground wires will connect to it. Ground bar kits are cheap if your subpanel doesn't come with one.

#6 solid or stranded (check listing of the GR connector), insulated or bare. HD carries the rods and the direct burial clamps.

mulltron 07-28-2011 01:31 PM

Thanks md and electures! That helps a lot!

Another question about installing the rod.

Is watering to soften the ground and lightly hammering the rod a little at a time, pulling out and redoing the way to install the rod?

Also, I know it would be near impossible to answer this one, but are there usually issues running into water or electrical lines during install? The shed is in a pretty big backyard and a ways from the house, but 8 feet is a long ways down. Is this something where we would need to check with the city on where the electical lines are or is this generally not an issue in a backyard? I am pretty sure there aren't electrical wires down there, but not so sure about where the water lines are. Is there another way to check and see where to put the rods?

wareagle 07-28-2011 01:34 PM

You can not put the ground wire and neutral on the same bus bar. The neutral bus should insulated from the panel. The ground bar should be bonded to the panel using the small green screw that comes with it. Check the panel and verify the above. If necessary you will need to purchase 1 additional bus bar.

http://img.photobucket.com/albums/v3.../Tallpanel.jpg

electures 07-28-2011 01:36 PM

Quote:

Originally Posted by mulltron (Post 695533)
Thanks md and electures! That helps a lot!

Another question about installing the rod.

Is watering to soften the ground and lightly hammering the rod a little at a time, pulling out and redoing the way to install the rod?

Also, I know it would be near impossible to answer this one, but are there usually issues running into water or electrical lines during install? The shed is in a pretty big backyard and a ways from the house, but 8 feet is a long ways down. Is this something where we would need to check with the city on where the electical lines are or is this generally not an issue in a backyard? I am pretty sure there aren't electrical wires down there, but not so sure about where the water lines are. Is there another way to check and see where to put the rods?

Get the biggest sledgehammer you can find, guess at a spot where you think there are no utilities and take out all your frustrations. You can also call for a mark out.

Red Squirrel 07-28-2011 01:57 PM

Probably a not a bad idea to get a cable locate either, just to be safe. Don't want to hit a gas line or you'll never live to finish the rest of that project. :laughing:

If it's the back yard the odds of anything there are probably slim but still worth checking.

mulltron 07-28-2011 01:59 PM

LOL thanks for the installation advice! That is the route I will go! The box I have has 2 bars for neutral (I see them connected and they have insulator behind them) but only a green screw and a hook for grounds. Looks like I need a ground bus bar kit.

I think I have the information I need. Thanks everyone!

a7ecorsair 07-28-2011 04:09 PM

If you have two bars, can the link that connects them be removed? By chance is it a GE panel?

rjniles 07-28-2011 05:09 PM

wareagle,

In the panel you show in the picture, why did you add a separate ground bar in the upper left side of the cabinet? Could you not have used the bar on left side of the panel as the ground?

mulltron 07-28-2011 05:12 PM

Quote:

Originally Posted by Red Squirrel (Post 695552)
Probably a not a bad idea to get a cable locate either, just to be safe. Don't want to hit a gas line or you'll never live to finish the rest of that project. :laughing:

If it's the back yard the odds of anything there are probably slim but still worth checking.

Thanks for the advice everyone!

How do I go about getting a cable locate?

jbfan 07-28-2011 05:14 PM

Quote:

Originally Posted by rjniles (Post 695663)
wareagle,

In the panel you show in the picture, why did you add a separate ground bar in the upper left side of the cabinet? Could you not have used the bar on left side of the panel as the ground?

The two bars are connected under the plastice, behind the main lugs.

Unless you can remove the connection, you have to install another ground bar.

jbfan 07-28-2011 05:15 PM

Quote:

Originally Posted by mulltron (Post 695664)
Thanks for the advice everyone!

How do I go about getting a cable locate?

http://www.call811.com/

wareagle 07-28-2011 05:28 PM

Quote:

Originally Posted by rjniles (Post 695663)
wareagle,

In the panel you show in the picture, why did you add a separate ground bar in the upper left side of the cabinet? Could you not have used the bar on left side of the panel as the ground?

This is not my picture. I found it Google and used it in an attempt to show the OP how the 2 bars were installed. I did not see the upper bar until I read your post.

brric 07-28-2011 05:31 PM

Quote:

Originally Posted by jbfan (Post 695665)
The two bars are connected under the plastice, behind the main lugs.

Unless you can remove the connection, you have to install another ground bar.

Looks to me like a Siemens panel with a clearly removable bar between the two busses.


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