Early, many portables do not have neutral bonded to the frame.
I have a 4 year old Coleman 5KW unit with a clear tag that says "Floating Neutral"
By the way another way around this problem is to use a transfer switch that switches the neutral. We use these all the time on jobs that have GFP protection.
Bob
Bob Badger Construction & Maintenance Electrician Massachusetts
Most portable generators state in the manual that you must remove the bonding jumper before connecting to building wiring. I have also seen stand by gen-sets where the neutral & ground are bonded. I won't mention names but one comes with a transfer switch that does not switch the neutral.There is no mention of removing the jumper in the manual
Switching the neutral only makes for a separately derived source, not a legally connected generator. You will still have a parallel path with the ground and neutral when the switch is turned to "generator". Thanks for the info on portable generators. I will have to modify my stance, and make sure I get one without the neutral bonded.