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Star point earthing

Practical Motorsport Wiring - Club Level

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Discussion and questions related to the course Practical Motorsport Wiring - Club Level

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I built a harness with the following grounds:

- Battery is in the passenger floor and negative goes to a bulkhead radlok connector

- All the interior grounds merge at the same bulkhead connector as the battery negative

- The other side of the bulkhead connector connects to the cylinder head

- All the engine-side grounds are connected to the same place in the cylinder head

- There's a ground strap between the cylinder head and the chassis

- The fuel pump and tail lights are the grounded to the body of the car near the trunk

Now, I know that even ignoring the tail ground (which was also treated as an exception in the worked example of the course) to make this comply to a star point earthing design I'd need 2 bulkhead connectors to have the interior grounds go to the cylinder head instead of meeting with the battery cable earlier in the path. The difference here is a ~300mm long 6awg battery cable, but does it matter enough to have an extra bulkhead connector?

I'm trying to improve how I approach these problems, so my current thinking is that even in the worst case scenario this piece of wire would see ~120A@10V during cranking, which according to some googling would cause a

Tadeu,

What did you end up doing? I'm in a similar boat...

Hum, it looks like part of my original question got dropped... I think the editor has trouble escaping HTML characters (< and >).

Andris, I kept things the way they were. I got a scope and measured the voltage drop during cranking and it was acceptable, so I just moved on with my life. I think you could end up with a small ground offset for the things grounded via the engine block vs in the cabin, but even during cranking, if my googling before the original question was right, I think it'd be about 0.2V, so I decided to live with it.

I'd love to hear from others that actually know what they are doing though, just to know if it makes sense.