Neutral Bonding......Again

[Iver]

Ok, I plan to have a plug from my main panel which will plug into either a shore power or generator receptacle. Fairly simple.

However, when I am plugged into the generator receptacle, and the generator is NOT running, but the inverter IS running, how do I deal with a potentially "double bond" situation.

The generator bonds the neutral and ground. The inverter automatically bonds the neutral and ground when it is operating and unbonds when ac power is applied.

The generator supplies power to the main panel.
The inverter receives power from the main panel and supplies power to a separate inverter panel.
Has anyone else thought about this?
I guess I could simply not leave the main panel plug in the generator receptacle?
Thanks, Iver.

[Len Silva]

I really don't see the problem.  The neutral is bonded at the generator or at the pedestal.  If AC is supplied to the inverter whether from the generator or the post, the neutral passes through the inverter.  When there is no AC to the inverter and it is making the AC, then the neutral is bonded at the inverter.

If you have one of those fancy-schmancy inverters that supplements the park power then I'm lost 

Len

[Stan]

Your genset has the neutral-ground bond whether it is generating or stopped. If your inverter makes a neutral-ground bond when the genset is stopped, you have two separate bonds on the system which is a violation. Obviously you understand this and the reason you asked the question.

Unless you put in a relay to lift the genset neutral when it is shut off, I don't see any answer. With the two bonds so close together, you will not get any significant amount of ground current.

In one shop that I rented, there was 5 volts between neutral and earth ground. I called in the inspection authority and they ran tests to determine the cause, and politely informed me "it won't kill you" and left.

[boogiethecat]

I was totally busted by Clarke Echols on this one, and he was right.  It's not necessarily about anything to do with the law, but when you "cheeze it" and you have those additional ground bonds all the time, and you try to plug into a campground that has a GFI, you're had because the GFI will see the additional ground path(s) and turn you off.  Other than that issue you're fine.

From what you've described I don't think you'll have any problems since plugging into a campground in your case will disconnect the genset, and the inverter will take care if it's ground on it's own.
It's only when you try to bond all three ( genset, inverter, shore cord) that you run into real-world problems.

[gumpy]

As he described it, he wouldn't have any problems plugging into a gfi because he's manually switching the plug from the genset to the shore power inlet.

Personally, I wouldn't worry about the extra ground bond in the system, as he's described it. It's the simplest way to maintain a fool proof system.

Craig

[Iver]

Thanks everyone,
   I find it interesting how what would be simple wiring in a house becomes very UN-simple when applied in a coach.   What do all these stick & staples do to address these problems?

   Anyway,  I think it is important to understand the wiring in your own coach.  If you do it yourself, (with the help of many others on these boards), it makes it easier to diagnose any problems etc.

  I must say I am much less worried about my situation after reading your responses.
                Thanks,  Iver

 

[DrivingMissLazy]

If you ever take your home on the road and start plugging into a shore outlet or hooking up to a portable genset or trying to operate the home off batteries and and inverter, you might run into similar problems. LOL
Richard

[boogiethecat]

Iver,
Good question !  The big difference between a house (at least in the USA) and the coach is that GFI feeding everything at the campground.  In a home you can get away with all sorts of code violations (ie incorrect grounding and neutral bonding) and your friendly power meter / company will still be happy to feed you all the power you want.  On the road it's not the same.  Interesting that in many european countries, they stick a gigantic GFI right at the power meter and that takes care of the entire home all at once.. there you couldn't get away with anything.

Stick and staples take care of it the cheap and foolproof way, by making you plug your breaker box in to either the genset or the shore post, but no possibility of both at the same time... problem solved.  All it costs them is a plug and a socket, instead of more expensive high power switches or transfer switches, which you often find on the big bucks stick and staples....
G