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Ground point on most harnesses

EFI Wiring Fundamentals

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I noticed on most harnesses, there is only one or two grounding points. Shouldn't hi amp equipment share a 1:1 ratio for wire size of power and ground?

G'day John.

You might find that the power wiring heading to many of the devices is actually pretty oversized. Even 22AWG wire on more fuel injectors is pretty overkill, for example. It can also seem like there are less ground wires than power wires, as the ECU 'low side switches' many of the actuators in the system, providing them with their ground, this is why ECU's typically have more power ground pins than power input pins.

Is there a formula of some sort for me to know that I am not undersizing my grounds. I typically run a ground for every power requirement. Question is how much load can a #22 wire handle for grounding.I have acutators, epas, lights, radio, lift pumps, and multiple fans in the car..Just want to make sure i am sizing the cable right.

Its the same way you size the wires on the power supply side, as the same amount of current entering your devices will be leaving it. So if you've needed to use 14AWG wire to supply wire to a fuel pump, for example, you will use 14AWG wire on the ground side also.

A 22AWG wire can handle the same amount of current on the ground side, as the power side, as its the current passing through it that will define the voltage drop across it. Anything more than a couple of amps on 22awg and I'd start looking bigger :-).