proper grounding on a gas tank

[love2fish]

I was reading a thread on Jamestown Distributers website about improper grounding and i wanted to make sure i grounded my gas tank correctly.
Originally (and still) I had just a ground from the tank's ground tab directly to my negative terminal on my #1 battery.

now that I'm switching to an electric fuel sending unit, I have the tank still grounded as well as the sending unit grounded (unit is grounded to my NEG bus bar). When i get my fuel gauge it will be grounded and I'll connect the POS leads....

I also grounded the fuel fill when i replaced that a few weeks ago... all that sound correct?

[Capt. Bob]

For me it is Chris.
Just the way I have mine.

[seabob4]

Yep.  The key is to have a lead from the tank to the ground bus, the fill to a ground bus, the sender ground to a ground bus (or, in the sender's case, if you want, all the way to the ground post on the gauge).  If you have continuity to ground throughout, all are happy...

[CLM65]

What is the proper size for the wire connecting the fill and tank to the ground bar?  I think I read 8 ga, but I want to be sure...

[seabob4]

Craig, per ABYC H-24, Sect. 24-15, Fuel system grounding...https://law.resource.org/pub/us/cfr/ibr ... 4.1993.pdf

Note there is no call-out for wire size, simply a requirement for resistance...

However, in ABYC E-01, Bonding in DC systems, it does state that the bonding wire shall be no less than 8GA...https://law.resource.org/pub/us/cfr/ibr ... 1.1973.pdf


Do I agree with them?  No.  And there must be a means of interpreting the section in E-01 that allows builders to use a smaller gauge, as there are no small boats (<26') out there that I know of that use 8GA, yet still meet ABYC req.s...

[CLM65]

Thanks Bob.  8 ga does seem kinda large.

[seabob4]

Craig, where I see 8GA is on twin inboards, where you have rudder ports, shaft struts, stuffing boxes, intake strainers, all that wonderful stuff that has to be bonded.  When they go that route, you'll usually see all the t/hulls and shut-off valves bonded as well...

[RickK]

What is the proper size for the wire connecting the fill and tank to the ground bar?  I think I read 8 ga, but I want to be sure...

I guess we go back to the poly tank "thing" again - do we need to ground the fill or the tank  

[gran398]

So what would be a good guage for the application?

They have a habit of corroding and rotting under the deck.

[RickK]

So what would be a good guage for the application?

They have a habit of corroding and rotting under the deck.

Are you talking about poly tanks?  

[gran398]

No, ground wires on tanks in general. They go green at the connection and look like a petri dish over time.

[Capt. Bob]

I have a 10 gauge on my tank and fill.
Same size was used on my CCP.

It was fine when I pulled the tank (CCP) 14 years later.

[Capt. Bob]

What is the proper size for the wire connecting the fill and tank to the ground bar?  I think I read 8 ga, but I want to be sure...

I guess we go back to the poly tank "thing" again - do we need to ground the fill or the tank  

I use a 10 AWG.

Poly or not, you still need to bond the fill, unless it is poly also.

[seabob4]

First, in response to Rick's question.  On a poly tank install, no bonding is necessary, not even the fill.  Any physical contact with the tank (through the fill hose) is with a non-conductor...plastic.  Thus, no static electricity can accumulate.  

What I would suggest on the tank sender (I think this is your big gripe here, Scotty...) is quality adhesive lined heat shrink terminals, a proper application of either dielectric grease or anti-corrosion spray, and stick with the gauge wire that does the trick...16GA.  Yes, you can step up to 14GA, but with a proper install, and proper maintainance, the 14 won't offer any less resistance than the 16.

The problem with tank senders and the wiring turning into something that looks like a spore colony in a petri dish is that nobody pays any attention to them!!  How many people pull their inspection pies and look at their wiring on a yearly basis?  How about every 6 months?  I'd say about 5% of the boater population.  And how many people, when they see a bit of water accumulating on top of their tank, stop their boating activities until they can track down the source and eliminate it?  I'd say about .05%!  

The point I'm trying to make is that there is no CORRECT wire size for bonding.  Yes, in theory, if the bonding system is part of a lightning protection system, and thus is terminated to a Dynaplate in contact with the water, then I would want 8GA.  But trust me, with the copious amounts of voltage a direct hit can produce, even 4/0 cable will be toast!!  The key is proper install and maintainance.  That keeps the resistance to a minimum, and keeps nasty little critters from colonizing on top of your sender...

[seabob4]

Bob, you are correct, E-01 does state that any metallic components of the fuel system must be grounded.  However, as an "out", typically, on new boats, which is what I am used to, boats which have poly tanks typically have plastic fills.