i was wondering yesterday... might sound like a really silly question but..

the fuel tank has to be earthed to the chassis right?

i was thinking about this in the rare case of lightning striking the car...

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Originally posted by robertst
i was wondering yesterday... might sound like a really silly question but..

the fuel tank has to be earthed to the chassis right?

i was thinking about this in the rare case of lightning striking the car...

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interesting question - one I have not come across before.

I find it hard to imagine how you would secure/fit a tank without it being earthed to the chassis - you would need to go out of your way to use rubber pads etc.

Now if the tank was not made of metal,then that would be easier to do.

I doubt you need to worry about lightning; there were stories about sparks when filling from petrol pumps years ago but I dunno if it was a urban myth thing.

My ally tank is sat on sponge strips which are stuck to painted chassis rails. The painted tank straps are similarly lined with sponge. This means that the tank is very nicely insulated from the chassis. The fuel level sender has an earth connection, so in theory the tank is earthed (proved by testing with a multi-meter). I'm not planning on adding anything elase to it though.

Surely your car's seperated from earth by those four big round black rubber things anyway?

David

I would have to agree... your tank should to be earthed in some way.

I would think that Lighting will be along soon to explain all, I think thats his job hence the name.

The tank needs to be earthed to the chassis so that the fuel sender works.

I have fitted a decent sized earth strap between tank and chassis on my car because the tank is on rubber mounts.

It would in my view, be a bad thing to have a potential difference between the tank and the chassis as this could lead to sparks between the two.

Of course, this would not deal with the issue of the whole car being at a potential to the ground due to friction static charge. This is where you get a belt when you get out of the car and touch the ground.

Mike

It technically shouldn't be an issue due to the whole faraday cage effect you get.

However, most theories can be proved wrong at some point, and I'd imagine you wouldn't want the proving to be while your sat 12 inches from a full tank of fuel that's not earthed!

Another view to throw in the mix....

If you didn't need the earth for the sender wouldn't you be better off with the Ali fuel tank completely isolated from the Chassis,

Then should a stray live (+ve) wire touch it, it wouldn't spark?

you need to earth the tank and the fller neck

because when the rubber build up some voltage it cant crate a spark on the filler neck with the pump filler pistol..

thats where you donīt want a spark where the gas goes in!!

I grinded / welded mig / tigged near the petrol tank with some fuel..

offcourse it was shutdown...

Tks

so an earth strap would do the job then?
i dont really trust on relying only on the sender earth,

to make things clear and safe for everyone, maybe i/we should create a kind of checklist of all earth connections to follow so as not to forget anything at the time of SVA/simply gettting on the car.

i have heard stories about how some garages here forgot to reconnect the engine earth strap after a rebuild, and interesting things happening!

Definately eart the tank and filler you also get static build up when you fill a tank, i checked out the fuelers at wattisham and they connect both the Helo and the tanker to earth to stop static.
As for the 4 rubber things providing protection, it's a soft top so no farrady effect, static is high voltage and can jump gaps, the car has a battery so is a circuit all on its own. If you dont earth the engine etc then the cranking amps have to find somewere to go and that could be up any small wire it can find.
I am going to check all my earths now.

I have a nice polished stainless steel chassis.


Like the old Martini advert.....


Any bolt, Any screw, Anywhere.




Paul G

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you would need to go out of your way to use rubber pads etc.

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