Grounding Help

[lowcountrygamecock]

Guys I need some more help. Just built a shop and am trying to get everything finalized. Here's the situation. I pulled 4/0 in conduit out of my main panel on the house out 25-30 feet to a 200 amp panel in the shop. I also pulled telephone and cable in the trench in a seperate conduit. The question came up about grounding and bonding. I know the 200 amp panel has to be grounded. Do I run that to the 6 foot ground rod at the shop or bury #6 from the house to the shop and tie it all to the ground rod at the house? What about the tv and telephone? Do I ground them outside splitters at the shop to the ground rod at the shop or run the #6 from rod to rod and tie to that?
Thanks

 

[Highbeam]

Is the building attached or detached? What exactly did you pull in the conduit? Three 4/0 conductors plus a ground wire?

For a detached building you need to have ground rods at the sub panel as well as ground rods at the house panel. You need to have a ground wire connecting the ground bars in both panels. The weird thing is that you do not bond the neutral to the box or to the ground bar at the sub panel as is done at the main panel. Keep the whites seperate from the bares on all circuits in the sub.

The real sparkies will be along shortly to comment.

 

[pattenp]

If your 4/0 is not copper then I hate to give you the bad news, the 200A rating on 4/0 AL is only when it's used as the main service entrance between the meter base and main panel. When 4/0 AL is used as a branch or feeder circuit the minimum amp capacity is 150A and the maximum will be 180A based on the temp rating of the insulation (wire type).

 

[pattenp]

I'm assuming your shop is detached. You need two 8ft ground rods driven six feet apart at the shop connected by #6 bare solid copper wire to the ground bar of the sub. Plus you need an equipment ground wire that runs from the ground bar in the sub to the ground bar in the house main panel.

The TV cable should have a grounding block and can be grounded by connecting to the ground wire to the rods, same goes for phone if the phone wire you installed has a grounding outer casing.

 

[Falcon67]

I'm assuming your shop is detached. You need two 8ft ground rods driven six feet apart at the shop connected by #6 bare solid copper wire to the ground bar of the sub. Plus you need an equipment ground wire that runs from the ground bar in the sub to the ground bar in the house main panel.

The TV cable should have a grounding block and can be grounded by connecting to the ground wire to the rods, same goes for phone if the phone wire you installed has a grounding outer casing.

What he said. Shoulda asked before the pour, 20' of #4 copper in the slab would have saved you the trouble of driving the rods. House needs the same two 8' rods on 6' spacing. As noted - 4 wire cable (L1, L2, N, G) remote panel neutral not bonded to panel.

 

[lowcountrygamecock]

Detached building. I have a conduit in the concrete that runs to the outside with nothing in it.

 

[lowcountrygamecock]

Oh and I had to drive rods anyway. County code required the rebar in the concrete be tied to a ground rod at the building.

 

[lowcountrygamecock]

I'm confused about everything else though after I re-read all this. Right now I have 4/0 in conduit from the house to the shop but not ground wire from the house to the shop. Do I need to go back and run a ground wire from the house to the shop?

 

[pattenp]

Yes you need to add a ground if you only ran three wires. What size breaker are you planning on using in the main panel to protect the 4/0 wire?

Maybe I should ask how did you connect the 4/0 into the main panel?

 

[pattenp]

This how your sub should be wired.

 

[lowcountrygamecock]

Double lugged at the main panel, no breaker. I may need to regroup on that.

 

[pattenp]

Maybe not if your main panel provides for it. Did you modify the panel by adding the lugs? Or are you saying you double tapped the main service breaker?

Double lugged at the main panel, no breaker. I may need to regroup on that.

 

[pattenp]

Hope you didn't do this. See this thread: http://www.garagejournal.com/forum/showthread.php?t=87107

 

[Aceman]

I'm assuming your shop is detached. You need two 8ft ground rods driven six feet apart at the shop

If he had rods driven in between the house and shop already, he could use those. I've driven rods at a pole with a service on it and then ran a feeder to a small shed 25-30' away. I ran a #4 bare in the trench from the shed subpanel back near the pole and attached to those rods.

But, if the existing rods are a mile away I would drive new ones. If only 25' away or so, I would use the existing myself.

connected by #6 bare solid copper wire to the ground bar of the sub.

It can be stranded or insulated too, it doesn't have to be solid or bare.

20' of #4 copper in the slab would have saved you the trouble of driving the rods.

A slab doesn't cut it, it needs to be in a footing or foundation.

Shoulda asked before the pour.

I think he should of asked a lot of things. This forum is only a click away, and he's making all of the mistakes we could have easily prevented if he had posted his plan first rather than simply doing it and asking questions after the fact.

What amazes me is these questions are asked EVERY SINGLE DAY and yet some people are still doing it wrong?

I can't say it enough, post up your plan or idea BEFORE doing it. It WILL save you a ton of trouble.

 

[lowcountrygamecock]

Let me explain in a little more detail and see if I can clear some of this up. I have a 320 amp meter base with bypass handle and an underground service from the utility. I went in on my side of the meter and added double lugs to pull the 4/0 out of there like it should be done. Not sure where that leaves me though and if that's right or not.


Now to answer the questions about the copper in the foundation. They placed rebar around the entire footer of the shop before they poured concrete and ran it cross ways across about every 10 feet best I can remember. It's all tied together. There is a ground wire currently bonded to that rebar and it's stubbed outside the building and tied to an 8 foot rod that I drove in. Can I use that or do I need to run #6 from the main panel still? Either way it's not a big deal.

And yes I should have asked first but sometimes a window of time pops up where I need to get moving and I don't have time to slow down and ask questions. I learned a lot about a lot of things building this shop and I will definitely plan better if I ever build another one. But hindsight is 20/20 and that's about all I can say about that.

 

[rockwithjason]

it happens to the best of us lowcountry. you can use the rod that you drove.

 

[pattenp]

I'm not totally familiar with what is required when you pull a second service from the meter base. But one thing I do question is having two 200A main service panels off of a 320A meter. I thought you should have a 400A meter to do this.

Also what is the wire type of the 4/0 that you used to the shop? I'm still questioning if you should be using it for 200A.

 

[Aceman]

But one thing I do question is having two 200A main service panels off of a 320A meter. I thought you should have a 400A meter to do this.

It's considered 320 amps continuous, 400 amps noncontinuous.

 

[Falcon67]

>A slab doesn't cut it, it needs to be in a footing or foundation.
I'll look in my book, but I think ground contact is ground contact. Mine is in a 12" deep footer, but still.