Grounding the Generator, RV

[thrushl]

OK, a question that has been bothering me. We just bought our first motorhome/RV in March of 2011 (2005 HR 45ft Navigator). Having spent years in the military with generators, the rule is ALWAYS ground them properly before starting. Additionally, I was reading that the 120 and 12 volt systems should not be grounded to the same ground.

Now, the question: "why don't I have to ground my RV to a ground rod before using the generator? Would it help/hurt anything if I did? How do the solve the problem (if it really is a problem) with grounding 120 and 12 volt systems in an RV? My owners manual is no help.

Thanks in advance for your help and answers.

Kindest regards;

Leo

[dickandlois]

Hi Leo! Welcome.

How to make it easy? It is a good question; The Coach is a world of its own when you are on Generator Power. Ground is the chassis or the ground plain. It floats on the tires.

When you are on shore power, the ground from the coach is then connected to the power grid ground and becomes part of the bigger world.

It's always good the check the shore power connections for proper ground, neutral and hot orientation, along with the voltage level.

Think your coach will have a 50 amp shore power connection. This is a four pin connector wired with 2-120 volt circuits, common neutral and ground.

Hope that answers your question.

R.M.

[thrushl]

Thanks for the response ****. I "sorta" understood the floating ground idea, but I have a slow "rolling" line of interference on my TV and the Aladlin system screen in the coach, BUT only when the generator is running. I have checked and cleaned all the grounding positions/points I can find. No improvement. So, I was wondering what next? All susggestions is apprecated.

Kindest Regards;

Leo

[dickandlois]

Leo ! OK, Now you need to check or tell me if there is an AC voltage present across the batteries when the generator is running.

If you have some AC ripple present only when the generator is running, There will be a junction box near the generator where the wires from the generator splice into the cable feeding the Main AC power panel.

With the generator off, remove the cover, generally a 4in. by 4in. box, check all the connections,splices and screw terminals for a good connection. There could be a ground wire running from this box to the chassis frame.

Any loose connections could be causing your problem. I'm thinking a ground loop problem caused by an open ground at / or in the generator; or in the ground between them.

This will cause a hum bar because the two 110 volt AC circuits in the generator are, for lack of a better term, talking to each other= ground loop!!!!

Also, check all the connections at the transfer Relays !!!!

Hope this leads you in the right direction. This problem can be caused by the smallest and seemingly unrelated item.

R.M. Thanks for the Question, This is a area that can go unnoticed.

[dickandlois]

A follow up to my response to Leo,

With a defective ground on the generator this can cause a number of problems with anything in, on; or connected to the coach when running on the Generator.

The generator Turbine section is damaged by Eddy currents that build up, burning out the Turbine assembly or any AC motors and devices. This current increases directly with the load on the generator. The greater the load, the greater the eddy current. Causing more and more heat to be generated until it fails.

R.M.

[thrushl]

You called it. Ground strap inside the generator compartment was disconnected. Connected it and added another one as a backup and the problem went away. Excellent job spotting the problem. Thanks SO much.

With greatest repect

Leo

[dickandlois]

Good news, Hay! your know a blind squirrel finds a nut sometimes.

R.M.