Common earth points

[Dave Lane]

Lucas through no fault of their own often had to put earth and live wires together taped up in one loom = bad idea .
Mainly as any fault ( especially in a car with no fuses ) just blows the lot all to feek and back ( twice ) , letting the smoke out of Lucas wire is a real bad idea and often terminal .
One thing i did on the Singer was to get ALL the earth wires out the loom and give almost everything its own earth wire ( as well as the circuit its own fuse )
To connect all these extra earths i created 4 main common earth points , two under the dash and two in the boot .
Apart from the wipers and the new oil temp gauge ive just fitted every earth in the front goes to one of these four blocks . ( one block not photographed )

[John A. Ross]

I like the common earth under the dash, you got the inertia cutout inide the car ? or is the black box something else ?
Its the pump cut off , as long as its on a solid surface it should work , dont fancy testing this for real though

[GaryHnz]

I fully understand the concern expressed Dave, but this old Audio engineer shudders at the very concept of running (earth) returns other than closely-parallel to the 'live' conductors. Especially the traditional automotive practice of "chassis earthing", which is both vulnerable to and a likely promoter of corrosion as well as all sorts of mutual interference.
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[Dave Lane]

I fully understand the concern expressed Dave, but this old Audio engineer shudders at the very concept of running (earth) returns other than closely-parallel to the 'live' conductors. Especially the traditional automotive practice of "chassis earthing", which is both vulnerable to and a likely promoter of corrosion as well as all sorts of mutual interference.
.

Are you saying this idea is wrong ? i never liked the idea of lives and earths all taped together .

[John A. Ross]

Gary, not sure I have ever seen close coupled connections on a car, not even in moderns now, in fact most of the 422/485/CAN bus are all diffs and floating.

Always shortest and fattest connection back to chassis for me. Cant beet the lowest Z path back.

Broken "earths" still haunt vehicles today but only seen corrosion on ones with +VE tied to chassis. Even on the old heaps we love to keep going bad return path I always find down to aged cable with cable rot, bad crimps (even on new pre-made cables) or simply folks ideas that 2.5mm CSA cable will do same job as 25mm as it is an earth.

That was the "earth" we had on Boris and not only had someone relied on metal/metal contact via the rear panel bolts as a way to connect to the battery (bad idea unless you bare metal which is a worse idea)



Imagine if that was in a cable bundle

Big fat, huge, massive ground connections to chassis for me and shortest path from load to metal as well as a big fat lead of its own straight from battery to engine block for starter.

[John A. Ross]

Think Dave has his common earth point almost same place as mine, did this in all our cars (except Boris/Mildred as they are stock)

Never actualy did a comparison on return loop impedances might do that. Lab supply as battery to level playing field and see drops on Boris (stock) vs Millie (short earth).Added to the list for a bit of fun.

[Jim McGurk]

All Swahili to me