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
Several items to consider (you may already have, but they are not listed in your post): 1) If there is an Underground Metal Pipe Water Supply to the building? If there is one then you MUST run your Primary GEC to within 5' where it enters the building. 2) Ground rods only require a maximum of #6Cu 3) When you say the GEC to the Rod is run to the Meter's Neutral Lug, are you saying it is under the same lug as the Grounded Conductor (Listed for that use?) or does it have its own lug? 4) Same as 3) but for the conductors feeding the 2-100Amp Main Disconnect Panels?? 5) Are the Exterior 100A Panels of the MAin Breaker style (because you "tapped" off the Meter some how = must terminate into a single Disconnect; AND the maximum of 6 Means of Disconnect rules) and then properly bonded, since this is your Service equipment? 6) And finally: Are you comfortable with the 4/0 AL SEU Cable if this system is loaded to the Max (200A Residential & 180A Commercial)??
I didn't put any NEC Section #'s because it appears you know your way around the book, but are just looking for some quantification.
#84954 - 05/18/0303:44 PMRe: service grounding/bonding
DJF, There is no GEC run to the water pipe so I am going to run the #4 to 1 panel then tap off to #2 panel with # 4 and then tap off to 30A panel with #8 these panels are inside residential basement. Then I am going to fix GEC outside. The meter socket has 1 lug for neutral and GEC.The meter socket lugs have 2 sets of lugs on load side to go to both 100A panels
#84955 - 05/18/0304:40 PMRe: service grounding/bonding
IMO Seems like your on the right track. However, the second ground rod will not satisfy code or make the system any safer. Here is the code below;
NEC 2002 250.50 Grounding Electrode System. If available on the premises at each building or structure served, each item in 250.52(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system. Where none of these electrodes are available, one or more of the electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used. (A) Electrodes Permitted for Grounding. (1) Metal Underground Water Pipe (2) Metal Frame of the Building or Structure. (3) Concrete-Encased Electrode. (4) Ground Ring. (5) Rod and Pipe Electrodes. (6) Plate Electrodes. (7) Other Local Metal Underground Systems or Structures.
Hope this helps! Dave
#84956 - 05/18/0305:11 PMRe: service grounding/bonding
Dave, Why wont the second rod satisfy code? The code says that the water pipe needs to be supplemented by a ground rod. Because 1 ground rod wont meet the 25 ohm rule you need to install another rod. Please clarify. Thanks
#84957 - 05/18/0305:41 PMRe: service grounding/bonding
The second ground rod MAY help with grounding the system but, the code requires the premises' water system to be bonded also. It is a matter of safety also.
NEC 2002 250.104 Bonding of Piping Systems and Exposed Structural Steel. (A) Metal Water Piping. The metal water piping system shall be bonded as required in (1), (2), (3), or (4) of this section. The bonding jumper(s) shall be installed in accordance with 250.64(A), (B), and (E). The points of attachment of the bonding jumper(s) shall be accessible. (1) General. Metal water piping system(s) installed in or attached to a building or structure shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with Table 250.66 except as permitted in 250.104(A)(2) and (A)(3).
Hope this helps! Dave
#84958 - 05/18/0306:13 PMRe: service grounding/bonding
gserve,- Did you do a ground test to see that you need a second driven electrode, or does your poco or local codes require it. Since your service already has the electrode,just bond the water pipe, jump the water meter,and bond the panels as you stated,and you should be good to go.
Shoot first, apologize later.....maybe
#84961 - 05/19/0307:38 PMRe: 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?