Inverter Grounding

[Gulf Comanche]

Sorry, I posted this question in the wrong category, here it is again:

I am in the last stage of my inverter installation. This inverter has a hookup for a ground wire, along with the positive/negative to the battery. The battery*(two 6v golf cart batts) are grounded to the frame of the boat, which is all aluminum. Do I need to hook up the ground wire mentioned above, or is the unit grounded by the battery's ground? Thanks.
Mike
Baton Rouge

 

[Capn Chuck]

Don't confuse grounds. The DC side of the inverter connects to the positive and negative on your batteries. Notice I did not say ground. Depending upon the inverter you have the AC side needs to connect to your AC loads, usually via a transfer switch, and to the GREEN ground on the AC side. This connection on smaller inverters is usually connected to the case. But then we can't be sure because you haven't given us all of the information. Chuck

 

[Gulf Comanche]

OK, a little more info. The inverter power comes from the batts then goes to several ac outlets in the boat. It is a separate system from the shore power, no connection between them at all, each has separate outlets. The neg side of the batt is grounded to the frame of the boat, which is entirely aluminum. Is this enough info?

 

[wingspar]

I'm far from an "expert" but I believe on a AL boat you would not want to use the hull as a ground. I believe it should have a sperate DC ground buss bar. Running any electrical currents through the AL hull can to bad things to it.

Dave

 

[Arctic Traveller]

Gulf Comanche wrote:

Do I need to hook up the ground wire mentioned above, or is the unit grounded by the battery's ground? Thanks.
Mike
Baton Rouge

Mike,* it's never a good idea to have your batteries negative side connected to a metal boat. It's unclear if the boat is used as a return path to the batteries, but in all cases, two wires should be used to complete a circuit, never one plus the boat.* As for your inverter 12v ground, you should run a cable equal in size to the two battery cables as a separate ground back to the negative side of the battery.* Often times, the lug provided by the manufacturer is too small to accommodate the large cable, so clearly there is a difference in opinion on this matter.* ABYC recommends (actually requires) the equal* sized cable in order to be compliant with their standards.* It's also not clear if you are referring to the A.C. side ground wire. I would highly recommend you get a copy of Nigal Caulders book on boat electrical and mechanical maintenance.* It's a great resource, and has never failed to answer questions I have had about any system aboard.* In addition, the manufacturers manual should address most of these questions.* ...........Arctic Traveller

Stop an see us at San Diego Trawler Fest* March 4,5 and 6th

*

 

[Gulf Comanche]

This is what I mean by "ground connected to the boat". Bottom right of the pic shows the ground wires from the batts.

 

[FF]

The drill is all AC power is grounded at its SOURCE.

The power pole ground is in the marina where the power enters the facility.

The noisemaker is connected to the ships ground by the transfer switch.

An inverter would be connected to its outlets with an internal ground IF all the circuits are all inverter only.

If it gets to the ships AC distribution usually a relay will connect the ground , while the inverter is on.

 

[Gulf Comanche]

Inverter is not connected to anything except batteries (2 golf cart 6V) and its outlets. Separate outlets for shore power and inverter. Grounded the inverter as shown on the instructions. Works fine. Thanks for all the replies.
Mike

 

[Forkliftt]

Mike,
I have the same post/ insulator inside my main battery box. The purpose I believe is to give you a way to attach several cables at the post, then run one cable from there to your battery post. The two bolts that hold the "post" to the stringer are insulated from the post.

 

[Gulf Comanche]

Steve & BS2:
Thanks for the info. I figured those lugs were separate from the frame, glad you confirmed. The inverter itself has a tiny attachment point on the rear side for ground wire. This I attached to the boat's engine room bulkhead, didn't know where else to go with it. So far everything works fine.
Mike

 

[FF]

The inverter itself has a tiny attachment point on the rear side for ground wire. This I attached to the boat's engine room bulkhead, didn't know where else to go with it. So far everything works fine.

Just get a good volt meter and measure the voltage in the water next to the boat , with the wire on & off.