Backup Generator Neutral Grounded?
quinnf
| Posted in Energy, Heating & Insulation on
I’m confused. I’ve read that some backup generators come with the neutral grounded, while when the same generator is used to connect through a proper transfer switch, the neutral is supposed to be left to float, and grounded at the main panel. And some transfer switches switch the neutral, while others do not. Is a puzzlement. Can anyone explain why the difference?
Replies
Every electrical system should have its metal mechanical and housing parts grounded so that there can't be a voltage difference between what you can touch and true earth ground. Even the little bit of coupling that comes from capacitance can be dangerous.
On a balanced three wire system, neutral should be connected to ground, but in one place only so that the grounded stuff like conduit never carries any part of the actual working current.
Why bond neutral to the boxes and conduit? If you tried to let the whole shebang float, odds are that the steel would get shorted to the copper someplace at random, and go undetected. By bonding neutral to ground, you ensure that any such short trips the breaker instead.
-- J.S.