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Tuesday, October 17, 2017
Question:
Re: CQD answer published Tuesday, October 10, 2017 - Generator Grounding 2
Connecting a generator utilizing a pole to switch the neutral (grounded conductor), and grounding the generator's neutral at a remote generator, does in most cases cause a high risk of parallel path ground loops. Unless the generator's ATS switches the complete building, then there are two separate ground electrode systems which come into play when the ATS switches to the generator.
In the LA area, one such connected system completely took out the very Emergency Broadcasting System the generator was supposed to protect. A very difficult to find problem, this was due to stray ground (Earth) loop currents over communication coax cable shielding caused by Earth-currents between the two electrode systems. Eliminating the use of the grounded conductor pole in the ATS, and bonding the generator's grounded conductor on the same electrode system as the building's service solved this "ghost" problem.
Scott Cline
A
Answer:
Hey Scott thanks for sharing your experience with generator grounding. Challenges can exist with either method - separately derived or not separately derived and multiple methods can be used to solve problems. There are a lot of 4- pole automatic switches used with separately derived generators in hospitals and other facilities without problems.