New Generator Installation where to ground

Im new to the site and have really enjoyed picking up information here and there. Now that I am in need of assistance so I have to be more than just a snooper... I am installing a new diesel generator into my boat that had a previous small diesel generator that was not grounded. Electrical issues can be difficult I know to answer so the easiest way to put the question. Where and how is the new generator grounded? The manual is very short on the subject probably by design and more written for the professional installer. It is a very small single cylinder unit that hooks up quite easily. The ground system in the generator is through the common wire connection. The generator has a post marked to ground. Would I take a suitable sized wire to the DC ground system? To one of the engines? (DC ground system) to the AC ground system? Which underway the AC ground system isn't really a ground correct? Thanks for any assistance or direction.

Well, you open up a dogs breakfast of issues when you talk about grounding to the DC system.

Ignoring that issue, generators are considered a power source by NEC, duh, right;-). So the neutral and the ground point are one and the same. Connect the white neutral and the green ground wire to the same terminal.

If it is a NextGen, download their installation manual at http://www.nextgenerationpower.com/Info/Support/UCM1-35.pdf. Even if it is not a NextGen the AC end is probably the same- a Markon.

A couple of safety issues:

There must be a breaker (30 amp typically) within a few feet of the generator. On the Nextgen, it is to the left of the hot terminal. Hopefully your generator has one in a similar location. If not you need to add one.

This is a personal safety as well as a system protection breaker. Anyone working on the generator should trip the breaker to make sure he is not being back fed AC. Should never happen, but....

You had a generator in the boat before, but it was not grounded? Wow!!!!

Well, anyway, you need either a transfer switch (typically a rotary switch like Newmar's) or separate shore and generator breakers with a lock out bar that will only let one be hot at a time.

This switch should be at the main AC panel or if it is shore and genset breakers, it will be part of that panel. It makes sure that only one source of AC can feed the system at a time. If two sources feed at the same time, one will be fried- guess which one?

If you don't totally understand these instructions and the reason behind them, then you probably should get someone more qualified to help you with this installation.

David

I admire your desire to become informed on the matters of correct electrical installations, but it would be well worth your time and $$ to observe while a certified pro makes the connections. Having a previously installed genset that wasn't grounded (assuming it was integrated in the boat's systems) is already enough reason to have a pro inspect the system as-is. So what....it costs you 90 bucks to have a few things checked. Money saved.

The usual setup is for the AC ground and neutral to be joined at the set.

These wires are lead to the transfer switch and you are done.

AC is grounded at the source , so the noisemaker and inverter will be grounded to the neutral where the juice is made , the dockside juice is grounded somewhere were the electric is brought into the marina .

No problem with a proper rotary switch.

My preference is to have a plug 50A 240V , on a wire that simply is plugged into a socket , one for shore , one for noisemaker and one for inverter.

KISS , and no damage when some auto start noisemaker starts to fight with the power pole.

Yes so true problem is every other guy i speak to at the marina is an expert but my 22 year old son has more respect for electricity. I need to find a BOAT electrician and will before powering up the new unit. The ground is carried through the neutral on the old gen set and the new one. The gen-set itself needs to be grounded to where is the question.

Monarch:

With all due respect, your latest question indicates a lack of understanding of everything that has been said in this thread. Be safe, hire a qualified electrician to wire your genset.

The previous ungrounded genset was a disaster waiting to happen. If someone had gotten shocked and killed with that genset, your insurance company probably would have denied coverage and you would be personally liable.

David

First off there is only one "ground"

Thats where all the metal, through hulls, engine blocks, everything else is connected to.

Tie your neutral and the frame of the generator together, at the generator and connect that to ground.

Then MAKE SURE that the device you use to switch between shore power and generator power switches both the neutral and the hot wire (s).

This is extremely important as you DO NOT want a path from the shore power and ground on your boat.

10-4 David and Kevin...My bad the old gen-set was grounded the surveyor indicated such in the report from last year. The confusion for me came from the new gen set having an additional ground point "equipment ground post" on the chassis and the old gen-set was different. ABYC certified tech coming tomorrow to once over the electrical system. Thanks for the input and Kevin cool website and marvelous Yacht.

I agree with those who recommend having a pro (a marine electrician) install the genset or at least do the electrical wiring.

Electricity and water can be a lethal combination.

A ground post is more than likely a connection to the bonding system from the tray and case to your through hulls and tanks if the tanks are metal. I suggest hiring a marine electrician if he does nothing more than instruct you on the wiring. A generator on a boat is considered a source however once the source is changed your white or neutral again assuming this is a single phase 110VAC 60Hz generator should never backfeed effectively bypassing the one point the they need to be electrically connected at the dock pedestal.
Bill

Thanks for the input form most of you...The hired ABYC Electrician was awesome and I learned a lot in three hours. The new MASE generator is a great machine.

Thanks for letting us know how it turned out. Three hours, sounds like it was worth it.

Actually he did not answer the question of what the electrician did with the "equipment ground post" in question.

So?

Capt.Bill11 said:

Actually he did not answer the question of what the electrician did with the "equipment ground post" in question.

So?

Click to expand...

Exactly, no fair to those who took the time to try and help, what did the fellow do in his three hours of awesomeness? Others could learn, don't be a "taker".