Stranded Marine Wire Gauge Size?

Solix 12″ Power Draw 2.88 Amps. Mounted on the bow 35 feet max 5/7 amp fuse?
https://humminbird.johnsonoutdoors.com/fish-finders/solix/solix-12-chirp-mega-si-g2?jo-page=2

Solix 15″ Power Draw 4.56 Amps. Mounted on the dash 30 feet max. 7/10 amp fuse?
https://humminbird.johnsonoutdoors.com/fish-finders/solix/solix-15-chirp-mega-si-g2?jo-page=2

What gauge of marine grade stranded wire should I use for each unit wired directly back to the main boat battery?
Will 12 gauge be ok, is it a tad bit heavy or a tad light?

AWG Chart

I’d use 10 for those runs.

According to the American Wire Gauge you will need 10 gauge.

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Oops… Didn’t see the link to the chart Dandorn. sorry.

According to both of the charts, I see 5 amps going up to a max of 40′, 4.56 amps is the highest draw and I would assume @ startup for the 15″ unit. Anyway that unit is @ the helm and I’m thinking a actual line length of 25′.

The 12″ unit will be on the bow and where it draws 2.88 and an actual 30′, I can’t think I’m not far off using #12. If I was to do a rewire, yes I’d use #10. I have 12 in the boat now and I ordered #12, before I knew for sure what I had. Ok, should have ordered #10 to have been safe, I just didn’t know.

Suppose if I see an issue with the units being underpowered I’ll just have to do new home runs, eh?

Not so sure it’s an issue of being under powered. It’s more an issue of draw on the wire. If the draw is too high for the wire it will heat up and it can get hot enough to ignite. Starting a fire.

I’m no electrician but that is what I understood when I did a full restore on my boat. Checked all my runs, amprage and gauged every wire accordingly.

But like I said I’m no electrician. I could be wrong.

Anyone care to chime in?

Kevin Collins wrote:

Not so sure it’s an issue of being under powered. It’s more an issue of draw on the wire. If the draw is too high for the wire it will heat up and it can get hot enough to ignite. Starting a fire.

I’m no electrician but that is what I understood when I did a full restore on my boat. Checked all my runs, amprage and gauged every wire accordingly.

But like I said I’m no electrician. I could be wrong.

Anyone care to chime in?

I would hope the fuse would blow before that happened,but then again it depends on where the fuse was placed,at the battery or at the closest point to the load.
hopefully the fuse is always placed near the battery.

@ the battery.

Thanks Kevin, The graft was what I was looking for. I did not take the time to search for it further than a quickie that I did.

Denny, are your distances one way or round trip.

When working with DC voltages the length has to be computed on a round trip.

The wire size is based on run length and line loss for a given current.

The fuse size is there to protect the wire and not the electronics. The fuse is larger than the current draw to support the current inrush from turning the unit on… (normally higher from steady state operation)

I don’t know where the chart came from but my guess is that it has an extremely high margin of safety built into it. The NEC (national electrical code) rates wire gauge ampacity differently.

The difference between marine wire and other stranded wire is the number of strands (usually higher strand count) for improved flexibility and vibration protection and tinned (for corrosion protection)

Your new sonar will probably run fine on marine stranded 14 gauge and I would install 12 gauge as a safety factor. Your experienced line loss will be less than 1/2 volt.

I am assuming you are running new separate wire pairs directly to the battery without any interruptions or additional taps. Solder the connections and protect them with shrink tube. Reduce the length of the supplied power cord (20-24 gauge) to within a foot or two of the unit.

djshannon wrote:

Denny, are your distances one way or round trip.

When working with DC voltages the length has to be computed on a round trip.

The wire size is based on run length and line loss for a given current.

The fuse size is there to protect the wire and not the electronics. The fuse is larger than the current draw to support the current inrush from turning the unit on… (normally higher from steady state operation)

I don’t know where the chart came from but my guess is that it has an extremely high margin of safety built into it. The NEC (national electrical code) rates wire gauge ampacity differently.

The difference between marine wire and other stranded wire is the number of strands (usually higher strand count) for improved flexibility and vibration protection and tinned (for corrosion protection)

Your new sonar will probably run fine on marine stranded 14 gauge and I would install 12 gauge as a safety factor. Your experienced line loss will be less than 1/2 volt.

I am assuming you are running new separate wire pairs directly to the battery without any interruptions or additional taps. Solder the connections and protect them with shrink tube. Reduce the length of the supplied power cord (20-24 gauge) to within a foot or two of the unit.

Thanks, djshannon. You are correct in your assumptions.