On 5/22/19 8:25 AM, Bill Prince wrote:
When we moved into our current home (over 23 years ago), it had gone through a number of additions. As a result, there were 5 separate panels and sub-panels. At that time, we hired an electrician to help sort out some anomalies. So the main panel and each sub-panel had a separate ground rod, with each panel/sub-panel tied to that ground rod. The electrician we hired, told us that was not code, and proceeded to remove the tie to each of sub-panels, and he left only the first tie at the main panel. There is quite a distance between the main panel and the furthest sub-panel (around 120').
The reason you don't want to do that is because you can induce current between panels on ground conductor with potential differences between each rod. Now you've got a possibility of stray current moving between panels across the ground.
And single point bonding of ground and neutral so that the ground conductor is isolated. If you bonded at subpanels the ground will carry half the neutral load.
As far as how it's grounded... cold water pipe, copper in concrete foundation or slab, ground rod... lots of different ways that could have been done over the years.
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