Mike Dolt Enterprises
Mike Dolt Enterprises
User: Ron Poehlmann, Location: Central Missouri
Asked on: Tuesday, March 22, 2011 at 4:01 am EDT
Answered on: Tuesday, May 14, 2024 at 3:05 am EDT
Question: I've come to a point were I need some help on a clubhouse project. I'm the EE on this project. 208V, three phase system, 1400A. We had the transformer pad close to the building and disconnect installed right outside the building. The MDP was MLO 30 ft inside the building. One of the owners dropped in to take a look and said the transformer and disconnect must be moved.Architect and EC have worked with POCO to move the transformer and disconnect to a new location about 230 feet away from building. All conductors underground.My question is about where the bonding jumper between the neutral and ground should happen in the new arrangement. Originally I landed the GEC in the outside disconnect and ran a ground conductor (with the phase conductors & neutral) from the SD to the MDP.With the service disconnect so far away, I want to treat the conductors from the disconnect to the MDP as if they were service entrance conductors. Can I do this and not install a ground conductor with the phase conductors? IE only phase conductors and neutral.The GEC will have to be landed in the MDP now. It doesn't make sense to me to run ground conductors between the Service Disconnect in this instance, but I can't find an exception in the code that will allow me not to.Does anyone see the fallacy in my thinking?
Your thinking is correct.
According to the National Electrical Code (NEC): 250.24(A)(5): Where service-entrance conductors are installed underground, a grounding electrode conductor shall be installed with the phase conductors and a grounded conductor. 250.24(A)(5) Exception No. 4 (2023 NEC): Where the service-entrance conductors are installed underground and the outer jacket of the underground service-entrance cable is continuous from the point of termination at the service equipment to the grounding electrode(s), an equipment grounding conductor shall not be required to be installed with the phase conductors and a grounded conductor.In this case, the service-entrance conductors will be underground and continuous from the point of termination at the MDP to the grounding electrode (which will be in the MDP). Therefore, you do not need to install a ground conductor with the phase conductors.The grounding electrode conductor (GEC) can be landed in the MDP, and the neutral and ground bonding jumper can also be installed in the MDP. This is a typical arrangement for underground service-entrance installations. Flag for review