More about standby generator grounding, GFP, and currents that go bump in the night

The issue of generator grounding, separately derived systems, and the application of three-pole and four-pole transfer switches continues to be misunderstood and misapplied by design engineers, in spite of several papers on the subject. Incorrect generator grounding and/or incorrect transfer switch selection can result in noncode-complying installations, intermingling of ground and neutral currents, and possible incorrect ground-fault sensing. In order to properly ground multiple service and multiple generator installations, the electrical design engineer must have an in-depth understanding of all of the variables involved