Kevin,

I am in the process of restoring a pontoon boat and doing some research on the fuel system.

If using a plastic fuel tank with rubber hoses that go from the tank to the metal deck fill on the side of the railings, should you ground the metal inlet to eliminate any static charge?

The U.S Coast Guard’s Boating Safety website says that any portion of the fuel system that is metallic has to be grounded. This confuses me because if you ground the inlet, it will essentially ground the entire marine electrical system, which could potentially cause corrosion issues.

Any advice you can give me would be great.

Thank you,

Bill

Hi Bill,

It is important to ground all of your boat’s metal fuel fill components together to prevent accidental, static discharge.

When fuel flows down a hose, the swirling action creates a static buildup. If the fill is not grounded to the tank, there is a change of a static discharge when the pump is removed from the fill which can cause an explosion. If the fuel fill is made of plastic, this static ground wire is not required.

Galvanic corrosion (the corrosion that occurs when dis-similar metals are electrically connected) will not be a concern. To cause galvanic corrosion, the two pieces of metal need to be electrically connected and submerged in the same body of electrolyte (water). If your boat’s fuel fill and tank are continuously under water, you have more serious concerns than galvanic corrosion.

Please let me know if you have any other questions,

Kevin

Kevin,

Thank you for quick response.

The way the boat was originally wired, there was a tank ground wire from the filler to the negative terminal of the battery.

The tank is plastic so I do not think bonding them together would discharge the static energy. The only metallic portion of the fuel system is the filler.

Is this the correct way to go about this?

Again, thank you for your help.

Bill

Bill,

Beyond connecting all metal components in fuel system that can come it contact with fuel, the system must also be connected to the boat ground.

The full intent of this practice is to give a low resistance path back to ground – metal fill – wire to tank – tank – to ground on boat – ground connected to metal underwater gear – boat in water – that will help prevent static discharge buildup.

• If your boat fuel tank has a fuel gauge sending unit, connect the static ground to the sender and the sender ground to the battery negative/ground bus.
• If your boat does not have a sender, connect the static ground wire directly to the battery negative/ground bus.

Hope this helps,

Kevin

Kevin,

This clears it all up.

Thank you very much for your help.

Bill

Hello Kevin,

My question is regarding marine wiring.

On my marine electrical, I’m using an isolation transformer in order to transform 220V to 110V.

Recently, the boat’s reverse polarity indication light is on. I’ve opened the circuit to see how this indication is measured and saw that there is a diode and led connected between the neutral and the ground.

I’ve realized that in the current situation the output of the transformer is basically floating, therefore the neutral line can have any voltage. One of the solution that I’ve seen online is connecting the neutral line at the output of the transformer to the boat’s ground (that is not connected to the shore’s ground). So I have several questions about it:

1. Is there advantage in connecting the neutral to the boat’s ground over working with floating voltage?
2. Is it ok to make this connection?
3. For about a year, the indication was off, what can be the cause for it to be on now?

Thanks in advance,

Ilia

Hi Ilia,

At the source of power, the neutral must be connected to the ground. With an isolation transformer, this is on the output (boat size). Please connect the output neutral and ground together immediately. It is an extreme shock hazzard as is.

The reverse polarity indicator is connected to the input side of your transformer. With an isolator transformer, the light is more of a nuisance than a concern. It is telling you that the polarity is reversed (Neutral is hot) on the input. Since you have an isolation transformer, you really don’t care as long as the neutral and ground are connected together on the output side.

Hope this helps,

Kevin

Hello Kevin,

I am really impressed by the Easy Add AC Shore Power System that you designed for your partner boat wiring site.

But, before I purchase the AC system, I have a couple of questions.

If my battery charger is mounted on the transom can I run 12 gauge marine three wire to the plug on back of panel and put a regular three prong plug on it? Marine grade of course. I did not want to run an outlet to the engine compartment.

Also could you please explain the placement of a galvanic isolator in the main line?

Finally, do you have any suggestions for marine grade three prong plug?

Thank You,

Morris

Hi Morris,

I am not fond of outlets in the engine room either. Even though it would be protected by the GFCI, you still have no idea if a non-ignition protected device will be plugged into the receptacle.

I would consider a studded battery charger as compared to a charger with pre-installed leads. You can run your 12/3 from the charger, up to the panel, and install a normal three prong plug at panel end. There is no need for it to be marine grade when it is in the cabinet in cabin. If this is not a possibility, I would make the charger AC connection outside the engine room.

Galvanic isolators are installed in the green grounding wire between the AC inlet and the marine electrical shore power panel.

• Cut back the white insulation.
• Cut the green wire.
• Install ring terminals on each end of the cut green wire.
• Connect them to the galvanic isolator.

Hope this helps,

Kevin