5 replies to this topic

[hoggy]

Hi is it possible to have too many earth wire's going to the same earth point on the body?

 

Thanks.

[nicklouse]

No. But yes.

Is the earthing point is not able to handle the current it could fail/melt/burn.

Bug that is a rather unlikely position in a Mini.

[KernowCooper]

every connection will have a certain amount of volt drop, multiply the connection and you have more volt drop, how many earth connections are we talking at one point?

[hoggy]

I have at the earth point, earths for.

6x gauges
9x gauge lights
Interior lights
Horn
Heater blower
Amplified aerial
Brake test circuit

Thanks for your help.

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[cal844]

You need to use 2 maybe 3 earth points for those circuits(well I would anyway!)

[tiger99]

Yes, you certainly need multiple grounds/earths. Not just for current carrying capacity, which can be improved by using a larger bolt, e.g. the battery ground and engine earth strap can carry 400 amps during engine start.

The other thing that matters very much is safety. What combination of things fails if the ground fails? For example it is no longer permissible to connect both headlights to the same ground points. Sudden double headlight failure on a dark, winding road is very bad, as I know from my own experience in about 1970. That was not a Mini, but it could well have been, as all early Minis would lose all front lights due to a failure of the single ground or the horrid bullet connector behind the top of the grille where it joins to both lights. The most recent Minis were built to later regulations and/or consideration of product liability and have left and right earths.

If you are maintaining, fixing or updating your Mini wiring in that area, please always take the opportunity to put in seperate left and right earths. A few minutes work may save your life.

At the rear much the same applies, but slightly less urgently because the car behind will have headlights and your Mini will have reflectors. But nonetheless, seperate left and right earths make fault diagnosis much easier. We have all seen cars showing strange things like sidelights and indicators glowing dimple when brakes are applied. Some peculiar effects will still happen if one earth of a separate left and right earth system fails, but the fault will be far easier to locate.

So it is not at all about current carrying capacity but the need to consider failure modes and their effects.

Ant there is one more thing, if you have an engine management ECU or other electronic systems. Voltage drop on the ground return line is critical, and if it is too high, massive damage is likely to its interfaces. I happen to be working for a company that makes ECUs for diesel truck engines at the moment, so I know...