cx19...grounding wire, fuel fittings

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vta
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cx19...grounding wire, fuel fittings

Post by vta » Sat Nov 22, 2008 9:41 am

setting up aluminum fuel tank in typical recommended location, gas fuel. i've been asking around locally about grounding wire and fuel fittings and have been getting alot of differing opinions about copper grounding wire and brass/plastic fuel fittings and also thread(pipe) dope/tape.

some say i don't need to ground the tank, others say copper /brass is ok if not in wet loc. and others totally disagree with these notions.

thoughts?

thx, vta


cb-vta

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Post by ericsil » Sat Nov 22, 2008 10:02 am

The term you want is bonding. Ideally, EVERYTHING metal should have a bonding wire running to your underwater zinc. This is not necessarily the same as the grounding wire that carries current for the circuits. I would think bonding would be critically important for an aluminum tank and fill fittings. Not only do you want to inhibit any static buildup during gas filling, but you want to try to minimize any corrosion from exposure to salt water. Get that tank hooked solidly to your zinc or you may find gas in the bilge sooner than you would like.

There are a number of books on the subject. I'd try the Electrical Handbook by Charlie Wing as a good starter.

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Post by TomW » Sat Nov 22, 2008 10:46 am

All metal gas tank components must be grounded to the grounding block of the elctrical system. This starts with the fuel fill if metal, the hose clamps, the grounding screw on the tank, and then to the grounding or negative block of the electrical system. A plain copper wire can be used.

The bonding system is not the same and applies only to external through hull fixtures so that they have the same voltage and do not create a secondary current that causes electrolysis and thus one type of metal rusting before another. As an aside some better bronze fixtures even come with a bonding screw.

The best way to remember it is insde/ground, water/bond.

Here is a grounding/bonding plate you can use instead of the motors if you want. http://www.defender.com/product.jsp?pat ... 2&id=28060

Tom
Last edited by TomW on Sat Nov 22, 2008 10:56 am, edited 2 times in total.

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Cracker Larry
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Post by Cracker Larry » Sat Nov 22, 2008 10:47 am

The USCG and the ABYC both say that a metal fuel tank and any metal component of the fuel system must be grounded, including fill fittings.

reference

http://www.uscgboating.org/safety/boatb ... anding.htm
FEDERAL LAW

183.572 - Grounding

Each metallic component of the fuel fill system and fuel tank which is in contact with fuel must be statically grounded so that the resistance between the ground and each metallic component of the fuel fill system and fuel tank is less than 100 ohms.



Fuel flowing from the dispensing nozzle into a fuel tank is a potential source of a static electric charge which could cause a spark between the dispensing nozzle and metal component of the fuel tank fill system. To prevent such a spark from occurring, metallic components of the fuel tank fill system and metallic fuel tanks must be grounded.

Grounding or bonding may be accomplished by connecting the metallic components electrically by running a wire from one component to the next, and so forth to the boat’s ground. Grounding can usually be accomplished by a connection to the common bonding conductor or the engine negative terminal.

If the fuel tank deck fill fitting is nonmetallic, and nonconductive hose is used as a fill pipe, there is no need for grounding the fill fitting. Chrome-plated plastic fill fittings are treated the same as metallic fittings.

NOTES:

If a metal hose attachment fitting is used, it must be grounded.
Fill cap retaining chains need not be grounded
For the wire you use a marine grade tinned copper like is sold here...

http://bestboatwire.com/

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tobolamr
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Post by tobolamr » Sat Nov 22, 2008 12:50 pm

I figured out how to build 'em... I know how to make a circuit... But there are some nuances I don't know! For clarification, from above:
Grounding can usually be accomplished by a connection to the common bonding conductor or the engine negative terminal.
For us clueless folks, can that just be run to the negative terminal on the crank bettery? Or is there a grounding stud on the outboard itself that I should look for?

Thank you!

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Post by TomW » Sat Nov 22, 2008 1:04 pm

T the negative system is all one system negative from battery to negative at outboard so negative at battery can be used. Or you can run it to your negative distribution plate which then goes to the battery if you have room on it.

Tom

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Post by Cracker Larry » Sat Nov 22, 2008 4:50 pm

Yes, almost everything negative on the boat is run to a common grounding buss. Some boats may have more than 1, but a CX19 will have at least one similar to my OD 18 in the console.

It is the brass strip with all the black wires to the right in this picture..

Image

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Post by vta » Mon Nov 24, 2008 10:05 am

thank you all;

one thing that is not clear to me, or did i miss something?

the part about running copper wire to an alum. tank for a ground (or bond) and using a brass/plastic fitting to the tank for fuel. i have always been of the understanding you cannot have copper and aluminum together.

vta
cb-vta

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Post by TomW » Mon Nov 24, 2008 11:10 am

I think you are thinking of housing when they used aluminum wire with copper switches and the aluminum wire expanded at a different coefficeint than the copper screws and became loose.

Using copper wire with aluminum screws does not present the same problem. There is no corrosion problem as they are very similar in that regard.

Tom

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Post by reddog » Sat Nov 29, 2008 12:14 am

vta wrote:thank you all;

one thing that is not clear to me, or did i miss something?

the part about running copper wire to an alum. tank for a ground (or bond) and using a brass/plastic fitting to the tank for fuel. i have always been of the understanding you cannot have copper and aluminum together.

vta
If there is a chance of getting salt water on it your correct. Aluminum and copper don't play well together. For the contact points of a grouding wire on an aluminum tank coat the connection well in dielectic grease.

Since brass fuel fittings are common when installing an aluminum tank I like to add an aluminum fitting onto the tank itself then go to the brass fitting. That way if there is any corrosion at the brass/aluminum point it is not on the threaded fitting that is often welded to the part of the tank. I have seen a number of installs where the tank is in great shape except for where the brass fuel fitting is attached to the tank. A real PITB to deal with as the aluminum threads in the tank are destroyed removing the brass fitting. McMaster Carr has a good selection of aluminum pipe fittings.

A good anti corrsion goop for aluminum is Tuff Gel. Google will show it.

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