DC high power common ground/negative wire thickness

Thread Starter


Joined Sep 24, 2018
Say I've got a 100-ah battery, and from this, I have 3 separate fused loads running from the battery.

1x10A motor, 1x2A AUX socket and 1x4A light bar.

Each load has its positive cable rated for the current draw and length. To save on expenses and to make life easier, I was going to run a single ground/negative to a terminal block and then off to each load.

Does this single cable need to be rated to 16A's?

Kind regards

Edit: before someone asks why can't the positives end with a terminal block, all loads are in the same place, but switches will be operated from different locations.
Last edited:


Joined Jan 23, 2018
The more detailed answer is that a conductor must be rated for the anticipated maximum current that it will carry. There are two reasons, the code reason is because of the issue of overheating, the other concern is the issue of an excessive voltage drop causing performance issues between the various loads. This may, or maybe not, be an issue in the given application.