Northwest Fishing Reports

I purchased a Dual USB Charger 5v 2.1/1 Amp & Power Socket Panel Mount Marine 12 Volt Outlet. It will get installed on the side of the dash by the steering wheel. The USB adapter will be used to charge cell phones and the 12 volt outlet will be used for a spot light. My boat has two 12 volt batteries. One battery is dedicated to running the trolling motor, the second battery runs the power to start the outboard mtor, Fish Finder unit and navigation lights. The distance from the usb/12v adapter to the battery is about 10ft. I'm not sure how much amps the spot light will pull. Image attached of the adapter with front and back view. Thanks for you help.

I'm looking for assistance for the following:
1) What size gauge wire would be recommended(18g, 16g, 14g, etc)
2) Would I use a single pair of wires for connecting the usb/12v adapter to the battery, or use two pairs of wires(one pair for usb and separate pair for 12v)
3) What size amp for the fuse/breaker should be used where the wires would connect to the battery
4) Could the usb/12v adapter be connected to the main wiring system under the dash without running the wires to the battery(if so where would be the best place to install the breaker/fuse)

Kfedka wrote:I purchased a Dual USB Charger 5v 2.1/1 Amp & Power Socket Panel Mount Marine 12 Volt Outlet. It will get installed on the side of the dash by the steering wheel. The USB adapter will be used to charge cell phones and the 12 volt outlet will be used for a spot light. My boat has two 12 volt batteries. One battery is dedicated to running the trolling motor, the second battery runs the power to start the outboard mtor, Fish Finder unit and navigation lights. The distance from the usb/12v adapter to the battery is about 10ft. I'm not sure how much amps the spot light will pull. Image attached of the adapter with front and back view. Thanks for you help.

I'm looking for assistance for the following:
1) What size gauge wire would be recommended(18g, 16g, 14g, etc)

You need to find out what the socket/s are rated for to choose correct wire gauge and fusing.

2) Would I use a single pair of wires for connecting the usb/12v adapter to the battery, or use two pairs of wires(one pair for usb and separate pair for 12v)

You probably should use two as I suspect fusing will be different between the two. You already know current limit for the USB side is 2.1amp max, so that's the most you should fuse that side for (I'd use a 2amp fuse).

3) What size amp for the fuse/breaker should be used where the wires would connect to the battery

What do the instructions that came with the sockets say?

4) Could the usb/12v adapter be connected to the main wiring system under the dash without running the wires to the battery(if so where would be the best place to install the breaker/fuse)

Yes if you have unused accessory circuits OR you have a way to tap into 12vdc and ground on your panel. You must fuse the new panel, whether off the accessory circuit or using a waterproof inline fuseholder.

You need to determine how much current your spotlight will draw so you can plan for correct gauge wire/fusing, however, if the socket is current limited, you will only be able to wire and fuse to the socket's max capability.

On the back of the 12v adapter it says the following "A13-142 12VDC/20A. So I'm assuming it's rate for 20amps. There are no instruction that came with the adapter.

This website http://www.offroaders.com/tech/12-volt- ... e-amps.htm has a chart titled "12 VOLT WIRE GAUGE VS. AMPS." So if max amp of the 12v adapter is rated for is 20 amp and considering it's 10ft from battery to this adapter, then 16g wire should be plenty, or just to be safe could go with 14g. And for the usb adapter since it rated at 2amp, then 18g wire will do.

Really need to know what the wattage of the spotlight is as it could easily draw more than what the receptacles are rated for. But heavier is better. For 20 amps (Receptacles rated current) running 10 ft I'd be running 10AWG but you could go 8AWG if the receptacles can handle it.

PS the usb adapter is typically 1 amp (unless you paid a lot for it) or less so you could wire them in parallel with no problem, size by your largest load on the main receptacle and of course you will want to put a fuse or breaker inline and probably an accessory switch.

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Would 12-2(12g) wire work that is used in home from electrical wiring? I have lots left over from remodeling.

Kfedka wrote:Would 12-2(12g) wire work that is used in home from electrical wiring? I have lots left over from remodeling.

No romex is not the stuff to use. At the bare minimum a stranded automotive type wire would work but ideally you want to use marine wire that has a tinned,stranded conductor. Spending more for the right stuff is a lot less painful than a melt down on the water!

db340 wrote:No romex is not the stuff to use. At the bare minimum a stranded automotive type wire would work but ideally you want to use marine wire that has a tinned,stranded conductor. Spending more for the right stuff is a lot less painful than a melt down on the water!

Absolutely! NEVER use household, solid conductor wire for your boat.

Here's a good read for marine wiring - https://www.bluesea.com/articles/1437" onclick="window.open(this.href);return false; and a nice chart for determining proper wire gauge and ampacity for length of run that meets USCG and ABYC standards. The forum chops the chart, but you can see the specific recommendations for critical and non-critical circuits matching your specific condition:



As you can see in the chart, 14awg will work up to 20' (wiring run is both directions to/from) since neither the spot light nor the USB port would would be "critical". If you want less voltage drop, use the critical column, and 8awg. Personally, I think that is huge overkill for what you're doing, and 12awg or 10awg would be fine.

Genuinedealz.com has a 12' spool of 14awg marine grade wire for $5.54, so just over $11 for wire. Step up to 10awg and price is $8.94 per 12' spool, so say $20, or you could split the difference and use 12awg at $7.15 per spool and have something around 6 - 7% voltage drop, PLENTY adequate for your short run and intended use. Want a simple approach? Get a 25' spool of 12awg duplex (just over $18), add marine grade terminal connectors (both ends), waterproof fuseholder, and a 20amp fuse for maybe another $10 and you've got good wiring designed for marine application.

I buy my wire at West Marine in the valley, it's convenient, close (sort of), and even though Genuinedealz has free shipping, I don't have to wait for stuff to arrive.

Db340 makes a good point, unlike automotive wire, marine wire is tinned full length under the insulation so is the correct choice for boat use. Automotive wire is cheaper because it isn't tinned and insulation is thinner, but it's certainly better than solid conductor house wire which should never be used.

I would have to agree with 10g or 8g for the distance. The spot light amps are important to know as said. Yes to Do Not use house wire. Not sure were you are mounting the adapter but you want it to be easy ish to get to the fuzeable link. I would recommend the square type they take the abuse better. You could run one wire to the cigarette plug then a jumper over to the usb side just have to add the fuse link in that jumper. Hope that helps.

Glad I asked about the wire type. Thanks for all your help guys, it was very useful and I learned a lot!