Grounding Electrode Conductor Sizing and Means of Attachment

[zander]

I'm installing a 1000 amp service, and I plan on using ground rods and the water main for my grounding electrode system. I'm using 4x parallel 250 kcmil per phase. According to Table 250.66, I'd be looking at a 2/0 grounding electrode conductor, if I'm not mistaken. My question is, how do I go about attaching such a large conductor to the ground rods and water main? I asked my electrical supplier and they didn't have a quick answer, which makes me wonder if I've sized the conductor wrong. Also, do I need larger ground rods for such a large conductor?

 

[GoldDigger]

The Code provides maximum sizes for GEC connecting ground rods. No problem there. I believe also an upper limit on size for GEC to water main.

 

[charlie b]

I don't know how to do the attachments. Someone else will have to answer that question. But you only need a #6 for the connections to ground rods. Reference 250.66(A). Welcome to the forum.

 

[Dennis Alwon]

Zander are you licensed or are you working for a licensed person?

 

[zander]

Thanks for the responses! GoldDigger, from what I've read, the upper limit on the GEC to the water main is Table 250.66. Over 1100 kcmil is 3/0 copper. Sky's the limit for the size of largest ungrounded service conductor. Dennis Alwon, I am the licensed person. charlie b, I'm familiar with 250.66(A). What generates some confusion on that one is that around here, for whatever reason, inspectors and electricians alike seem to thing you need #4 copper to the ground rods, even for a single-phase 200 amp service. I didn't know if there was something tucked away in the code that would make you bump it up depending on what other electrodes make up the system. Thanks for the answers so far. Keep em coming!

 

[infinity]

#3/0 is the largest GEC ever required. A #6 to the ground rod electrodes and you're done. Wondering why if you have a 1000 amp service that you don't have a CEE?

 

[Hv&Lv]

Connector like we use.
https://m.platt.com/Products.aspx?pid=756059

not sure why you want it, but...

 

[zander]

CEE?

 

[zander]

Hv&Lv what do you mean, "not sure why you want it?"

 

[Hv&Lv]

CEE?

Concrete encased electrode

 

[Hv&Lv]

Hv&Lv what do you mean, "not sure why you want it?"

Charlie b, & infinity have referenced 250.66(a).
it says #6 is all you need, as long as your using an 8’ rod or approved plate.

maybe I’m missing something in your post?

250.66(A) Connections to Rod, Pipe, or Plate Electrodes.

Where the grounding electrode conductor is connected to rod, pipe, or plate electrodes as permitted in 250.52(A)(5) or (A)(7), that portion of the conductor that is the sole connection to the grounding electrode shall not be required to be larger than 6 AWG copper wire or 4 AWG aluminum wire.

 

[zander]

Wondering why if you have a 1000 amp service that you don't have a CEE?

Infinity, I wish I did. This is old construction. Got bought by a small printery. It has a 200 amp single phase service currently. It's a glorified pole barn with a concrete slab. No rebars exposed though. That was back before they did such things.

 

[Hv&Lv]

I hope I’m corrected here if I’m wrong.
I may be missing something in your post with what’s in my head.

your installing a 1000 amp service.
Bring your 3/0 GEC and terminate it in the CT cabinet
Water line(10’ or more as electrode) #2.
supplement with a rod, #6 to the rod.

 

[zander]

Hv&Lv I'm not following. I'm looking at Table 250.66 and see that the largest GEC that I need is a 2/0. What would I be bringing a 3/0 from to terminate in the CT cabinet? How is the GEC from the water line not based on Table 250.66 and should be a 2/0?

 

[zander]

How do you arrive at #2 for the water line?

 

[zander]

I hope I’m corrected here if I’m wrong.
I may be missing something in your post with what’s in my head.

your installing a 1000 amp service.
Bring your 3/0 GEC and terminate it in the CT cabinet
Water line(10’ or more as electrode) #2.
supplement with a rod, #6 to the rod.

4x 250s in parallel for each phase= 1000 kcmil= 2/0 GEC

 

[Hv&Lv]

Heck, I’m confusing myself trying to multitask..:ashamed1:
(4) 250’s, 1000 kcmil.
250.66. 2/0 to CT cabinet.
2/0 to bond the waterline
#6 to ground rod.
all tie to utility ground in CT cabinet.
there are many water pipe connectors to bond the GEC to the water pipe

i was thinking about the largest size 3/0, shouldn’t have included it in the other post.
#2 was a screwup..

 

[zander]

Dang! I was hoping I was about to find out I could run #2. One thing still isn't computing. When you're saying 2/0 to the CT cabinet, where is that coming from?

 

[JoeStillman]

Don't forget to bond to the building steel.

I always run the 250.66 - sized GEC to the water Line and Bldg Steel, #6 to any ground rod(s) [250.66(A)], #4 to a rebar [250.66(B)] if there's access to the footing. Note that the #6 and #4 GEC sizes apply only if they do not extend to any other sort of grounding electrode.

 

[Cow]

We use Burndy U-bolt style water pipe clamps for attaching larger conductor sizes like you're using to water pipes.

We would take your 2/0 and #4 into the swbd/metering cabinet/etc.

Sometimes we'll use an irreversible crimp to attach the #4 to the 2/0 if both grounding electrodes are in the same vicinity and then just run the 2/0 back to the swbd, etc.