Bonding Question

[sweetwaterec]

I will be installing a new aluminum fuel tank (mounts under deck to the cross members) and stainless flush mount deck fuel fill on my pontoon boat. The mfg of the fuel fill states that the filler tube should be bonded. My questsion is this; I assume I should bond the fuel fill to the tank by running a wire from the fill to the tank and then from the tank to the grounding bar that is wired to the negative side of the engine? Advice and help is certainly appreciated.

Thanks,

Stephen

 

[saumon]

Re: Bonding Question

Exactly. Fill ground wire to tank ground then to boat ground.

 

[Grandad]

Re: Bonding Question

Just curious. I'm not a toonie (but I am a tinnie), so I don't know how your tank is situated. If the aluminum tank is fastened directly to the aluminum structure and the filler neck is in electrical contact with the aluminum structure, is there any point in running an additional bond wire? - Grandad

 

[Georgesalmon]

Re: Bonding Question

Yes there is. Even if your metal tank is touching the metal boat you could have corrosion destroying the connection. The bonding system is to help get rid of static electricity. Static is usually high voltage and low current, that means long sparks can jump a gap easily. And then, your fill hose is usually rubber and you need a path for the static to follow to ground. Not to mention its a requirement of the coasties and ABYC. Course you don't have to pay attention just the manufacturers have to. Still there's a reason.

 

[Grandad]

Re: Bonding Question

Yes there is. Even if your metal tank is touching the metal boat you could have corrosion destroying the connection. The bonding system is to help get rid of static electricity. Static is usually high voltage and low current, that means long sparks can jump a gap easily. And then, your fill hose is usually rubber and you need a path for the static to follow to ground. Not to mention its a requirement of the coasties and ABYC. Course you don't have to pay attention just the manufacturers have to. Still there's a reason.

Ya, George, when in doubt, adding the bond isn't a big deal. I have a pretty good understanding of the reason and the "mechanics" of the electrics. As you point out, static is high voltage and since it can jump a distance, the corrosion between mating aluminum isn't likely to interfere much with the electrical discharge path. I teach electrical theory to electrical apprentices, so I come at this with a good respect for rules, but I also tend to examine the theory each time the rules are applied. Since I'm not familiar with pontoon boat gas tanks, I picture an aluminum box clamped in place to the aluminum frame with perhaps even a fuel fill welded to the box, without need for a rubber fill pipe. Even with a non-conductive fill pipe (they do make conductive rubber ones), if the filler is also electrically connected to the aluminum structure, the intent of the rule is met. As an aside, a copper bond conductor fastened to an aluminum fitting can have its own corrosion issues if not correctly installed. - Grandad

 

[sweetwaterec]

Re: Bonding Question

Ya, George, when in doubt, adding the bond isn't a big deal. I have a pretty good understanding of the reason and the "mechanics" of the electrics. As you point out, static is high voltage and since it can jump a distance, the corrosion between mating aluminum isn't likely to interfere much with the electrical discharge path. I teach electrical theory to electrical apprentices, so I come at this with a good respect for rules, but I also tend to examine the theory each time the rules are applied. Since I'm not familiar with pontoon boat gas tanks, I picture an aluminum box clamped in place to the aluminum frame with perhaps even a fuel fill welded to the box, without need for a rubber fill pipe. Even with a non-conductive fill pipe (they do make conductive rubber ones), if the filler is also electrically connected to the aluminum structure, the intent of the rule is met. As an aside, a copper bond conductor fastened to an aluminum fitting can have its own corrosion issues if not correctly installed. - Grandad

Makes sense, although my setup will be filler through wood decking under a seat, with filler hose etc. No good continuity with the tank.

What's your recommention on bonding the copper conductor and aluminum fitting to prevent the corrosion issues? I assume galvanic corrosion due to copper/aluminum? I'l' throw another issue into the mix. The tank is Aluminum, filler neck is stainless and the conductor is copper.......

 

[Grandad]

Re: Bonding Question

Makes sense, although my setup will be filler through wood decking under a seat, with filler hose etc. No good continuity with the tank.

What's your recommention on bonding the copper conductor and aluminum fitting to prevent the corrosion issues? I assume galvanic corrosion due to copper/aluminum? I'l' throw another issue into the mix. The tank is Aluminum, filler neck is stainless and the conductor is copper.......

Hi Sweetwater. Unless you're boating in saltwater, corrosion won't likely be much of an issue. However, if your fittings are like most, they'll be hidden away where you won't notice corrosion, so perhaps a little precaution is worthwhile. Even in freshwater, I would use quality ring terminals, crimped with a proper crimping tool and then slather some "dielectric" grease all over the exposed conductor, ring and fastener. Use of a lock-washer is a good idea You won't have any corrosion problems, just peace of mind. - Grandad