As far as I understand, a generator in a typical field scenario does not need to be grounded. But I do see ground used often. So what is common practice?
If not required by code for safety, wouldn't a ground on a generator have other advantages, as in regard to static, lightning, QRM? Or could it even introduce problems?
73 de Marc DL1MRD
actually, a two part question and answer.
Part 1: should I ground the genset chassis to a local ground rod?
Part 2: should I attach the 120V output neutral to chassis? ie: what to do with the neutral strap.
Any condition of the above will still result in correct delivery of power to the load.
my answer to part 1: Locally grounding a genset makes it unlikely to receive a static shock from touching the metal frame; although this is not usually a problem.
my answer to part 2: This gets more interesting. Hazardous voltages derived from even higher voltage is normally ground based. This has two purposes; first, if lightning hits, there is a path to earth. You don't want 100kV pulse at your toaster! Two, if certain faults occur, like a primary to secondary step down transformer short develops, or a open primary/secondary ground occurs, OR, if a high(er) voltage line falls or otherwise makes contact with the 120V occurs, some measure of safety exists. Here, you don't want 9kV rms on your toaster! Those events should activate upstream overcurrent protection devices.
BUT, a portable genset has an output that is not likely to get hit by a lightning bolt, and has no proximity to other, higher voltage sources. Plus, an ungrounded output, L and N, become safer, since a grounded human contact can occur with either, and not result in a dangerous shock.
So, the "general" rule says to attach genset neutral to earth in "large installations", but not in "small installations". A setting like a carnival should be considered a large install, and grounding provides some measure of protection when the ferris wheel gets hit by a bolt of lightning; attempting to keep the surge headed to ground and not appear in force everywhere.
For a couple of tables of ham equipment in the field, I would suggest no ground contact. For RFI, not so clear. Depending on frequency, grounding at one end can still result in high RF at other points, depending on freq and cable length. On the other hand, if a AM BC station is nearby, then grounding the N side might tend to settle down the entire AC system from RF.