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I live in the Philippines but I have the same US electrical system (2 x 110V hot + 1 x neutral). I have two ground rods buried 8 ft. deep and connected to the main panel. Netural and ground are bonded in the main panel. And from the main panel, all 4 wires (2L + 1N + 1G) go to sub panels. Ground and neutral are isolated from each other in the sub panels as they should be. From the sub panels, I can create 220V sockets (2L + 1G) and 110V sockets (1L + 1N + 1G).
I tried using a current clamp meter to make sure that there is no current in the whole ground system. From the sub panels going back to the main panel, the ground wire read 0A, so all good. But in the main panel itself, I measure the ground electrode conductors (wires connected to the ground rod) and I see one of them have around 0.5A of current. Is this normal? If so, why?
I know for an unbalanced circuit, I would get a small amount of current in the neutral wire. And since neutral and ground is bonded in the main panel, I would think all of that current will go through the neutral wire going back to the transformer because the path via the ground rod back to the transformer has very high resistance (earth), no? So why then is there a current reading in the grounding electrode conductor?
Also, what is the reason why it's not dangerous to bond neutral and ground in the main panel? I know that if you bond neutral and ground in the sub panel, then you have two paths for the return current which is dangerous for everything connected to ground especially for metal disconnects but how is that different from when neutral/ground is bonded in the main panel?
I tried using a current clamp meter to make sure that there is no current in the whole ground system. From the sub panels going back to the main panel, the ground wire read 0A, so all good. But in the main panel itself, I measure the ground electrode conductors (wires connected to the ground rod) and I see one of them have around 0.5A of current. Is this normal? If so, why?
I know for an unbalanced circuit, I would get a small amount of current in the neutral wire. And since neutral and ground is bonded in the main panel, I would think all of that current will go through the neutral wire going back to the transformer because the path via the ground rod back to the transformer has very high resistance (earth), no? So why then is there a current reading in the grounding electrode conductor?
Also, what is the reason why it's not dangerous to bond neutral and ground in the main panel? I know that if you bond neutral and ground in the sub panel, then you have two paths for the return current which is dangerous for everything connected to ground especially for metal disconnects but how is that different from when neutral/ground is bonded in the main panel?