I was expecting that in something like Debbie's situation they wouldn't tie the generator's ground and the stage together. The genny just sits out back running away with stuff plugged into and it's ground potential floating to wherever. Meanwhile the stage with all the metal exposed to humid east coast air and sitting on moist concrete or in a dirt field is much closer to true ground.
But.... what is "true ground"? Sure, that stage is sitting on a lot of
soil, a physical construct, but "ground" is an
electrical construct, and more than that, it is an
artificial electrical construct. "Ground" doesn't exist unless we make it exist.
The problem is that this stuff is both trivially simple, yet gets hard real quick.
The purpose of "ground" in your home or office is so that if a hot conductor comes in contact with "ground" (this is a "fault condition") then there will be a big flash, lots of current will flow, and the circuit breaker will open switching off that hot conductor. The ground conductor is the same as the neutral. A short from hot to ground is the same as a short from neutral to ground. The difference between neutral and ground is that the ground is not ordinarily expected to carry current, only the neutral does that.
The reason that electrical ground exists at all is to make stuff safer. Lets assume there was no ground, as was common in the USA a few years back. Lets further assume you have two guitar amplifiers, with wired guitarists connected. Let us further assume that both amplifiers have a fault each, they have a short in the power cable to the chassis of the guitar amp. Final assumption is that one short is to one wire of the power cable, and the other amp to the other. Everything works great until the two guitarists touch each other, and then both guitarists get shocked as the power goes from one mains wire, through the fault in one amp, down the guitar lead, to the guitar, the guitarist, the body contact, the other guitarist, his guitar, the lead, the other amp, and its fault to the other wire. Ouch. I've used guitars and amps as an example, but it could be any pair of household or office appliances.
So, the idea of grounding was developed. The neutral of the power system was connected to "ground", which meant water pipes, the soil outside, the chassis of the guitar amps, everything metal and electrical. So everything you can touch is grounded, so you cant get a shock between metal stuff. All this grounded metal stuff provides an "equipotential zone", and you are safe in your equipotential zone. If a fault condition develops between neutral and ground, nothing bad happens, as they are the same potential. Approximately. If a hot conductor touches anything grounded in this equipotential world, then flash, bang, breaker opens.
That's why we do grounding: it provides an equipotential zone where all exposed electrically connected metalwork is connected together ("bonded") to prevent a shock potential developing between stuff.
Phew.
The genny just sits out back running away with stuff plugged into and it's ground potential floating to wherever. This is an entirely likely scenario for a lounge person doing a little municipal affair. What happens when someone holding a mic or a guitar grabs hold of part of the stage? If there is a ground fault in their amp?
What indeed?
If the output of the generator is indeed floating (ie there is no connection between the neutral pin of the outlet and the ground pin) then there is no solid path for current to take from a fault between hot and the ground pin. Thus with a single hot to ground short, the generator breaker will not open. Everything connected to this generator will no longer be "floating" (ie, connected to nothing) but will be connected to the hot (or neutral, depending on the fault) of the generator.
This could be bad, or unnoticeable, depending on a lot of things. But one thing is sure; if a second fault develops, to the other wire of the plug, then there is the possibility of real danger.
The first and best line of defense here is GFCIs. Even a small leakage current caused by a fault with a floating generator will be enough to open the GFCI and preserve life.
The second thing is actually the number one rule of sound system engineering; have a single ground for the system. If there are two (or more) independent generators, common their grounds so you still have a common ground in the system. Anyone remember the poor mans distro? That keeps the grounds communed even with different supplies to different parts of the system.
If you are paralleling generators, like the Hondas, I've had no experience of those particular generators, so don't know how they work their magic, and especially in terms of grounding. The manual says they have a ground terminal, which connects all metal stuff but is not connected to the generator output. So you would think that step one is join the frame ground terminals together, "just in case". These are floating ground generators, and many of the RV crowd then link neutral and earth pins, so that the supply looks the same as it would for a house. If that is possible, that would be a sensible thing to do, as then the supply in a field looks a lot like a supply in a building, with the same sorts of safety advantages as outlined above. if the generators have integrated GFCIs, that might be harder.
Caveat - there are a number of ways that small generators can be "grounded", before doing anything, be sure to understand how the grounding works.
