?
Thursday, February 11, 2016
Question:
I have a 1200 amp single phase 120/240 service on a single family residence. A single ufer ground connection point was stubbed up at the opposite end of the building. I have 6 200 amp disconnecting means installed at the service location. Can I install a single # 4 copper conductor from the connection point to the service equipment and jumper from one disconnect to the other with a # 4 jumper? Thank you for your time ! John Mallory
A
Answer:
Hey John thanks for your question and wow some house, must be a large family! Yes, somewhat, but make sure the AHJ agrees. A common grounding electrode conductor is allowed for multiple disconnecting means as stated in 250.64(D)(1). The common grounding electrode conductor is sized based on 250.66. In general the sum of the areas of the largest ungrounded conductor from each service disconnecting means would be used to size the common grounding electrode conductor. But 250.66(B) allows the grounding electrode conductor to be sized not larger than 4 AWG copper. I know it doesn't say common grounding electrode conductor but it doesn't exclude it either. Grounding electrode taps will need to be installed as stated in 250.64(D)(1) under the conditions provided so jumpers between the service disconnecting means are not allowed, that is the somewhat part.