Mike Dolt Enterprises
Mike Dolt Enterprises
User: Gategator37
Asked on: Wednesday, April 6, 2011 at 12:02 pm EDT
Answered on: Tuesday, May 14, 2024 at 3:51 am EDT
Question: Here is my scenario: The electrician used a Main Bonding Jumper from the Neutral Conductor to the Grounding Electrode System located in the 112.5 Transformer. This is all fine and dandy; however, at the neutral bar (at transformer) he also landed his EGC's from the primary and secondary panelboards. Is this installation ok, or should he of attached the EGS's to the Ground Bar located at the Transformer. I don't know if the only thing that can attach to the neutral is the "bonding Jumper".Thanks in advance for your input.
The installation described is not acceptable according to the National Electrical Code (NEC).NEC Requirements
Grounding Electrode System (GES)
All EGCs (Equipment Grounding Conductors) must be connected to the GES at a single point. (NEC 250.50)
Main Bonding Jumper (MBJ)
A single MBJ must connect the neutral conductor of the system to the GES. (NEC 250.28)
Neutral Bar and Ground Bar
The neutral bar and ground bar must be separate and distinct from each other. (NEC 250.24(A)(5))
In this scenario
The EGCs from the primary and secondary panelboards should be connected to the
ground bar, not the neutral bar. The MBJ should be connected from the neutral conductor only to the GES.
Reasoning
Connecting the EGCs to the neutral bar would parallel the neutral and ground paths, which is not permitted. This could create a dangerous situation in the event of a fault or surge. The MBJ is specifically designed to connect the neutral to the GES to ensure a low-impedance path for fault currents.
Correction
Disconnect the EGCs from the neutral bar and connect them to the ground bar. Ensure that the MBJ is connected from the neutral conductor only to the GES.
Additional Notes: The GES can consist of multiple grounding electrodes, such as a grounding rod or water pipe. The location of the GES is typically outside the building, close to the transformer. It is important to follow all applicable NEC requirements and industry best practices to ensure a safe and compliant electrical system. Flag for review