To bond or not to bond, that is the question...

[bevans6]

Apologize in advance, this has been beat to death but I seem to have a need to drag it out and hit it a few more times.

situation - I have a Yamaha EF3000iSEB generator, which is a nice little inverter gennie, very quiet, does a very nice job, and I am very happy with it.  I have it installed in the forward AC bay, and connected through an  Iota 30 amp transfer switch that is shore power priority, and switches both neutral and hot.  The issue is that the generator does not bond neutral to ground internally, it floats neutral.

I'm comfortable that it would be good to have neutral bonded to ground when using the generator.  I want to understand where the best place to bond neutral might be.  I see three choices - inside the generator, which requires modifications to a unit under warranty that I would rather not do, bond inside the plug into the generator, or bond inside the transfer switch.  I wonder what people though of these, and if there are technical reasons to prefer one to another.  Or even to leave it as is and not have neutral bonded to ground when I am running off the generator.

thanks, brian

[Sean]

Brian,

The correct place is inside the generator itself.  Since this is such a common need, I have to imagine that Yamaha has a procedure for it that does not violate the warranty.  I would consult with Yamaha's tech support on this before working out a different solution.

-Sean
http://OurOdyssey.BlogSpot.com

[bevans6]

Sean, I appreciate the advice.  Unfortunately, Yamaha's official position on this issue is to not offer any advice, for liability reasons.  Kind of a sign of the times, I guess.

edit - btw, I hope you get your windshield wipers fixed soon and easily!  If you had the same sort of storm we did yesterday, it was a doozy.  I did 200 miles in my pickup, towing my race car trailer, in gusty winds up to 50 mph.  I should pay more attention to the weather forecasts!

Edit no. 2 - Sean, I found where you answered this question for another poster back in July.  The advice you gave then I can implement now, so thanks again.

Thanks, Brian

[Len Silva]

The fact that it's an inverter type unit makes a little different from a conventional generator.  I would be hesitant to into the innards without some good information.  I would bond the neutral as close to the generator as possible, perhaps within the output connection box.  Also be sure that the generator itself is well bonded to the chassis.

[bevans6]

Len, my generator is bonded to ground to the main ground buss in the transfer switch box, through the pigtail that plugs into the twist-lock plug on the generator front panel.  I thought that was adequate, what do you think?  That is the main AC ground for everything, it's a big twisted bare ground cable tied directly to the chassis.  There is a separate ground lug on the generator, designed for a ground stake, but I thought to avoid having the generator grounded to the bus chassis twice.

Brian

[Sean]

Edit no. 2 - Sean, I found where you answered this question for another poster back in July.  The advice you gave then I can implement now, so thanks again.

Great, that saves me from having to type it again.  For anyone following along, Brian is referring to this thread:
http://www.busconversions.com/bbs/index.php?topic=12547.0

Len, my generator is bonded to ground to the main ground buss in the transfer switch box, through the pigtail that plugs into the twist-lock plug on the generator front panel.  I thought that was adequate, what do you think?  That is the main AC ground for everything, it's a big twisted bare ground cable tied directly to the chassis.  There is a separate ground lug on the generator, designed for a ground stake, but I thought to avoid having the generator grounded to the bus chassis twice.

If the generator is "installed" in the coach, the code requires it to be grounded to the bus chassis at the generator frame, in addition to the electrical connection through the pigtail to the ground bar in the panel.  You can use the frame ground lug Yamaha provides for this purpose; code requires a minimum #8 wire for the frame ground strap.

There is no problem with the ground being tied to frame in multiple places, and, in fact, code requires many items to have direct frame grounds, including the main panel, any transfer gear, inverters, converters, and generators.

What you don't want, as you know, is any more than one single place where ground and neutral are bonded to each other.

-Sean
http://OurOdyssey.BlogSpot.com