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Tuesday, August 28, 2018
Question:
Re: CQD answer published August 9 & August 21, 2018 - Service Equipment 3
Discussion on a main disconnect located at a remote pedestal feeding a home. Your answer was that the service is at the pedestal and a feeder would then supply the home and a 4 wire feeder circuit would be needed. My question how we ground this after we install the bonding jumper. There is no concrete encased ground at the pedestal. So does this then not need a concrete encased ground? Also the interconnect bonding bar needs to be installed at the service location. There will be very little use for those bonding bar at a remote pedestal. I'm not sure that a run of a fifth wire back to the home to make these connections could create a situation of a potential difference between the ground and the service. Curious what you think.
Rod Christmann
A
Answer:
Hey Rod thanks for your follow up question. A grounding electrode conductor connection must be made at the service as stated in 250.24(A). A concreate encased electrode is not specifically required at a service but some type of grounding electrode is - as sated in 250.50.
A main bonding jumper must be installed in the service disconnect enclosure as stated in 250.24(B). It provides the path for ground fault current from the equipment grounding conductor (s) to the grounded (likely also a neutral conductor) conductor which is connected to the utility transformer. The grounded conductor can not be reconnected to ground at the load end of the feeder as started in 250.24(A)(5). This is to avoid objectionable current as stated in 240.6. An equipment grounding conductor must be connected to the service equipment and extend to a panelboard supplied from it.