I am stating that there is "some" coupling. How much is dependent on the individual generator and the connected load.
By bonding the "neutral" to the frame/earth of the generator, the variability of this coupling is no longer a variable. With a known configuration, certain protective devices can act in a predictable manner. (GFCI)
Are protective devices necessary? That is a different question.
Is bonding of any of the output leads required or even desirable? It all depends on the design of the system.
Will not bonding any output lead cause a problem? In most cases of using small portable generators, I think not.
Can it cause a problem? Under the right circumstances, absolutely!
Do I think the bond is required? Right now, as long as the generator is a truly independent system, I do not believe it is necessary. As soon as it gets connected to an external system, such as an fuel supply, battery charger, remote monitoring system, block heater, an external structure like a building, hard wired phone system, or anything else that makes it not independent, then a bond MAY be required.
Larry
