I periodically run in to this with distribution panels: The common and ground conductors are not separated, and they are all connected at one bus bar that is bonded to the panel - wired as if a main panel. No separation of the conductors. Is this a safety issue that should be fixed ASAP? I know it’s improper, but what level of heiarchy of concern? Safety, Major, or fix it in a timely manner?
The problem is that with the equipment grounding conductor (EGC) and the neutral connected together at both ends the neutral current will flow on the EGC which under normal conditions never has current flowing on it. This could be dangerous if the neutral were to open.
Dangerous, but only IF the neutral conductor become disconnected, right? And then, if the neutral conductor was disconnected, where is the danger, inside the panel box, or at the plug? Help me understand!
If the neutral opened then the neutral current would be present on all of the metal parts because they are (incorrectly) bonded to the neutral. In theory if you were grounded and touched those metal parts you could receive a shock because your body would be in parallel with the path of the neutral current.
There are varying opinions as to how dangerous bonding the neutral at a sub-panel actually is when the normal neutral connection is intact. Hazardous or not, it is a violation of the NEC and needs to be corrected when discovered.
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