CC to battery cable size??

[Nan_wpg]

my controller is a Victron 250/60. the manual does not say what size wire for controller to battery connection, or the ground wire size.

for reference a morningstar controller manual does say 6g for the battery wire, and 8g for the ground.

I did a google and diysolar search and everything was all about the wire size for array to controller.

so does 6g sound correct? 8g for the ground? (I,thought power and ground are the same size, not sure why Morningstar is,different)


and could someone point me in the direction how to determine this? (Is it amperage capacity of the wire?)

 

[Flatpicker]

Wire size is based on what amperage that conductor has the potential of carrying. The larger the amp load, the larger (in diameter) the wire needs to be. Remember, lower numbers (in wire gauge) mean a larger conducto except when you get to “0” gauge then the wire size would increase with “one-ought” (1/0), then “two-ought” (2/0) etc.
Regarding the smaller gauge ground wire - that is pretty common to go down one size for the ground wire. It has no effect concerning safety or circuit performance but can make the conductors easier to pull thru conduit with the smaller ground wire.
6 gauge wire is rated at 60 amps so your controller is probably rated for 60 amps (sorry, not familiar with the Victron units- but I’m assuming with the model number that 60 amps comes into play somewhere….lol)
In short, you can use #6 on the ground too. It won’t hurt anything, but you can get by with #8 with no safety concerns.

 

[Bluedog225]

Yes. The ampacity needed to carry the current.

I believe the theory (or fact) is that the ground only carries momentary current. Therefore, it can be smaller. Though I’d get independent confirmation from others before relying on this.

I always go to the blue sea wire ampacity chart.

Part 1: Choosing the Correct Wire Size for a DC Circuit - Blue Sea Systems

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