Bonding/Grounding Aluminum Fuel Tank

[mr300z87]

I was in the process of cleaning up some wiring on my V210 Invader cuddy cabin and I notice a green wiring running from the neg battery terminal to the fuel filler. On closer inspection I found that it went in to the fuel tank compartment where the wire was spliced with a grounding lug but not connect to the tank. My question is should this be attached tank (sending unit mounting screws)? And second I have read that this should be bonded to the engine not the neg battery terminal? I want make sure it is correct and safe. I work in the telcommunicaton wiring field so I know the importance to proper grounding and bonding. Thanks in advance for the advise.

Mike

 

[Silvertip]

Re: Bonding/Grounding Aluminum Fuel Tank

The negative terminal of the battery is the same as the engine block since the very large negative battery cable connects to the engine block. There normally is a ground tab on the tank. The fuel filler neck and tank should be grounded.

 

[mr300z87]

Re: Bonding/Grounding Aluminum Fuel Tank

Thanks for the response. I did not see a specific tab for grounding could I use the same tap as the black wire or one of the screws from the sender? As long as it is bonded to the ground/Neg battery circuit?

 

[fucawi]

Re: Bonding/Grounding Aluminum Fuel Tank

It would be normal to ground the tank to the hull with a strap not a wire ( large surface area) and then this does not form part of any other system that can be disturbed.burnt out or disconnected .

Wires is for current straps is for static

 

[dingbat]

Re: Bonding/Grounding Aluminum Fuel Tank

A Caution About Grounding Your Deck Fill:
http://www.boatus.com/foundation/findings/findings40/links.htm

Please check with your installation instructions regarding grounding requirements or refer to a marina or boat yard that is versed in American Boat & Yacht Council (ABYC) construction standards.

Because fuel nozzles are metal and the flow of fuel through it generates static, a small but dangerous spark (called an Electrostatic Discharge or ESD) can occur when the nozzle is inserted into a metal filler neck. To prevent sparking, a ground wire must be attached from the metal deck fill unit to the boat?s bonding system. Also, it is important that the nozzle remain in contact with the metal deck fill at all times while refueling. Never wrap a nozzle in an absorbent pad or rag so that it prevents a good contact between the nozzle and metal body of the deck fill. When refueling portable fuel tanks, always place directly on the ground, never on a plastic truck bed-liner or a dock made of synthetic plastic wood. Good contact between a portable tank and a solid grounded object is essential.

Special Warning for Plastic Body and Metal Fuel Caps: Deck fill units that have a plastic body with metal components such as a metallic lid or metal retaining chain, are NOT to be grounded. Read the important Safely Message & Technical Bulletin issued by the United States Coast Guard (USCG) in February 2005:

Coast Guard Warning: Fuel Fill Technical Bulletin:

Recent events have caused the boating industry to examine the policy regarding the bonding of plastic body fuel fills with metallic caps and retaining chains. Existing USCG & ABYC policy states that the bonding of these components is voluntary. A study by IMANNA Laboratories has shown that connecting the metallic retaining chain and cap of a plastic body fuel fill assembly to a boats bonding system may result in electrostatic discharge from a land-based fuel pump nozzle to the metallic components of the assembly when the boat is not in the water. This condition does not exist when the boat is in the water due to the equalizations of the ground potentials between the fuel pump nozzle and the boats bonding system.

It is recommended by ABYC and the USCG that new and existing installations of this type of fuel fill assembly DO NOT INCLUDE any attachment to the boats bonding system. Existing connections should be removed from the point of connection to the boats bonding system to the fuel fill assembly. Removal of the metallic components of the assembly is not necessary; however, the U.S. Coast Guard and ABYC still require that METALLIC body fuel fills be bonded.

For further information contact:
John Adey, ABYC (410) 956-1050 ext. 29 jadey@abycinc.org
Richard Blackman (202) 267-6810 rblackman@comdt.uscg.mil

 

[mr300z87]

Re: Bonding/Grounding Aluminum Fuel Tank

Now I am confused? Does the green wire running from the filler neck (metal I think) which runs to the hatch where the sending unit is where it is spliced but not connected to the tank then runs to the neg battery terminal need to be bonded to the tank? It seems like it should but I want be sure before I ground the tank.

 

[Grandad]

Re: Bonding/Grounding Aluminum Fuel Tank

Now I am confused? Does the green wire running from the filler neck (metal I think) which runs to the hatch where the sending unit is where it is spliced but not connected to the tank then runs to the neg battery terminal need to be bonded to the tank? It seems like it should but I want be sure before I ground the tank.

Since you have a metal filler; yes, bond the filler to the tank and the tank to the negative battery terminal. What you're trying to establish is a common electrical potential between all parts that could become energized, including by electrostatic forces. As long as all conductive parts are at the same potential, there can't be any arcing and sparking between components near flammable vapours. Most flexible (rubber) fuel pipes are compounded such that they will conduct to bleed off any charge that the pipe itself might develop. - Grandad

 

[mr300z87]

Re: Bonding/Grounding Aluminum Fuel Tank

Can I bond to the same location as the black (Sending unit ground) wire or one of the sending unit mounting screws?

 

[Grandad]

Re: Bonding/Grounding Aluminum Fuel Tank

Can I bond to the same location as the black (Sending unit ground) wire or one of the sending unit mounting screws?

That's what I would do, as long as there is definite metal to metal contact with the tank. You could drill a hole for a nut and bolt connection if there's sufficient lip at the edge of the tank provided you don't drill through a roll-welded seam that would compromise the tank. You would still need to have a negative wire connection to the fuel sender flange just to ensure the tank and sender body are at the same electrical potential.
- Grandad

 

[Ike-110722]

Re: Bonding/Grounding Aluminum Fuel Tank

I worked in the USCG Office of Boating Safety that issued the above quotes about grounding fuel fills. I left shortly before that was issued but am very familiar with it. First, it is intended to apply only to boats that are fueled at auto gas stations (land-based) and not marine stations. Second it applies only to boats with solely plastic fuel fills.

For all other boats:
When fuel gushes through a fill hose it can build up a static charge that needs to be dissipated to ground. So, the fill (metal fill or metal plated fill) is normally connected to the tank with a green wire. (green wire is the grounding circuit on boats) The tank is then grounded with a wire from the metal fittings on the tank if the tank is plastic, or from the tank if the tank is metal, to the grounding point on the boat. Yes the negative terminal on the battery is at the same potential as the engine block so it would seem that running the green wire to the battery negative would be OK. But this is should not be done. On boats the grounding point is the engine block. On boats with more extensive electrical systems there may be a grounding buss (a cable or copper strip that runs the length of the boat, that is connected to the engine block. On boats with less extensive systems the grounding point is just the engine block. It is considered bad practice to run any wiring direct to the battery other than the red positive wire that goes to the Battery Switch, and the negative (black) wire that goes to the engine block. Your boat may have a negative buss bar that is connected to the engine. In that case the green grounding wire should go to the negative buss bar. That eliminates a lot of wires connected to the engine block, and means just one wire (black wire) going from the Buss Bar to the engine.

Anyway. yes your tank should have a grounding wire connected.

On trailerable boats with plastic (not metal plated) fills with only a metal chain that holds the cap from falling off, that usually fill up at a land gas station, the fill should not be grounded to the tank and the boats grounding system. But the tank should still be grounded.

A slight correction: I should have said solely plastic fuel fills with metal caps and retaining chains should not be grounded. Why do I always realize these things after I have hit the submit button? Must be old age!