service grounding/bonding

[gserve]

I checked on a service today that only had 1 ground rod installed. The ground wire was run outside and hooked up to the meter socket neutral lug. This is a 2 gang socket fed with 4/O SEU. There is a 30A panel(QR water heater)hooked to 1 socket and 2 100A panels(fed with #3copper SEU each from the other socket. 1 panel is lighting/appliances etc. The other panel has circuits for electric baseboard heating. There is no ground to water pipe. I would like to add 1 ground rod(6') apart outside and then run a bare #4 to 1 panel and tap off with a #4 for second panel and then tap off with a #8 for 30A water heater service. These conductors are going to be run outside panels and use split-bolts to tap to to each panel. Does anyone see a problem with this? Thanks

 

[gserve]

Re: service grounding/bonding

Hey guys, I also noticed that there was no bond screw in these 2 100A panels. These panels are Bryant panels with raised neutral bars(insulated from the box). There is no way to bond neutral bar with a screw. So I am going to install a bolt on lug by drilling and tapping a 8/32 screw into the panel to hold on the lug than run a piece of # 8 bare strand from bolt on lug to neutral bar. Do you see any problem with this?

 

[luke warmwater]

Re: service grounding/bonding

First post: Adding a second rod isn't a problem. But your minimum wire should be #6, so the #8 from the 30a is too small. You could use #4 from the others if you want to, but #6 is all that is required 250.66(A). These must also be continuous to the rod(s), so you cannot split bolt outside of panels. You'll need to run all 3 to the rod(s).
You say there is no ground to water pipe. do intend on grounding it?
Second post: The problem that I see is that this is not the 'listed' way to bond the neutral bar and I have seen this fail inspection.

 

[gserve]

Re: service grounding/bonding

The #8 is for the jumper(tap)from the #4 that goes to water main(bond)

 

[rickg]

Re: service grounding/bonding

First off, is the 2nd meter position rated for 200 amp? (the 2 100 amp panels connected to this meter). Secondly, there is nothing wrong with running the GEC from the meter socket as long as there is a lug to land the conductor on, in this case it may be better to ground to the meter. This one point grounding method eliminates the possibly objectionable neutral currents on the ground wires running from panel to panel. If you can bring your H2O bond to the meter socket all the better. You can run a ground rod conductor from the first rod to the second rod as long as you use separate acorn clamps for each conductor. If you bond & ground from the meter base, there is no need to bond & ground from any of the panels, in my opinion this is the best method... again no objectionable neutral currents on the ground wires. Thirdly, how do they land the 2 100 amp conductors on the load side meter lugs? 2 wires under one lug? That does not fly.
You are correct, you can run a #6 wire from each panel, connecting each one seperately to a #6 conductor going to the ground electrodes. Each ground wire from each panel must be connected seperately to the GEC. These connections must be made outside of the panels. See the picture in the 2002 nfpa nec handbook. The inspector may not approve of this as the nec says you must try to avoid objectionable neutral currents on the ground wires. In my towns I try to steer the electricians into grounding/bonding at one point inside the meter base. Our local utility company allows this, fortunately.