Announcement: Boat Wiring Questions?

Questions about marine electrical? Easy Ac/Dc has the answers.

Whether you are in mid-project or just curious, there are loads of posts on the site to check out. If you’re trying to track down more specific marine wiring info, please use the search box on the right or check out the list of various subjects farther down on this page.

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Thank you for visiting. We look forward to hearing from you and hope that you will be able to come back often.

Lingering Light

VHF Radio

Boat Wiring Guys,

I put in new VHF radio into my sailboat. The installation seemed to be successful except...

Now when I turn off the marine electrical panel switch for the VHF, the green light from the breaker goes out but not right away, slowly turning off in about half a second.

Is there any problem with this? Did I screw something up?



It is not a problem.

The light in the switch gets power when the output side of the switch has power. The residual light is caused by a capacitive charge that is in the VHF radio. This capacitor in the radio helps with noise and voltage spikes but will give the appearance of voltage on the power wire which makes the light stay on.

Hope this helps

Self Lifting

Hello Easy,

I came across your site somehow and thought I would send a question.

If I can get my boat onto my lift next year, I am wondering about different ways to power the ac shore station hoist mortar without shore power. Is there an economic way to utilize the boats batteries or use an inverter, or a very small generator that could be on the boat? Last year I left a portable generator on the dock, but I would hate to get it stolen and am just hoping there is a way comparable to using a dc motor (which I don’t have). boat lift motor

My boat is less than 3000 lbs and the motor presses against the wheel to rotate it.



Hi Brian,

It is amazing how low the lakes were last summer. Hopefully they don’t drop too much more.

The most economical solution would be to buy an inverter just large enough to run the AC motor on shore station. The shore station should either have a wattage rating or a current draw (watts=current*120).

Running the inverter for a short period of time to lift your boat should not be enough to completely discharge your boat’s batteries. If your boat has a battery switch, I would make sure it is not in the BOTH position when you are using the hoist to help prevent draining both batteries.

IMPORTANT; If your inverter is not ignition protected, do not run it in the engine room

Hope this helps,


Cord Cutting

Hello Easy,

I am installing a new battery charger, a Guest Intelligent Charger, on my Irwin 25.

The new charger has an AC Plug and of course in the instructions recommend plugging into an AC receptacle protected by a GFCI breaker.Wire stripper

Is there any good reason or regulation, ABYC or other rules that would preclude me from removing the AC plug from the charger and terminating those wires directly to a dedicated breaker in my AC distribution panel?

The bulkhead where I am locating the new charger does not have a whole lot of room and I can save wiring real estate if I do not install an outlet. The run from the new charger to the AC distribution panel is no more than 2’.


Hi Andrew,

There are no ABYC regulations against hard wiring. In my opinion, it is safer to have a charger hard wired into the panel than to have any outlet in the engine room. You have no idea what other, non-ignition protected items may get plugged into the outlet. Also, GFCI outlets should not be used in an engine room because they are not ignition protected.

But, before you cut the plug off, I would make sure the charger works. You may void your warranty if the plug has been hacked.

Hope this helps,


Aluminum Fuel Tank Grounding


I am told a copper ground wire should never be connected to a aluminum gas tank. Is that correct. I ask because my new tank has a ground tab welded on it.

Thanks.RDS aluminum fuel tank

Captain Ron

Hi Captain Ron,

Copper wire – either tinned or not tinned – is the marine standard for boat wiring.

When grounding a metal fuel tank, the main requirement is to keep the resistance between the fuel tank and the boat’s ground to one ohm or less.

Here is ABYC standard H-24 says:


Each metallic fuel tank and metal or metallic plated component of the fuel fill system, which is in contact with the fuel, shall be grounded so that its resistance to the boat’s ground is less than one ohm.”

Hope this helps,


Itasca Inboard

Hi Kevin,

I have a 1986 Itasca motorhome in which I have installed a 2001 Chevrolet 8100 Vortec Mag HO Engine from a Mercury inboard set up.

My problem is with the wiring loom and the fact that the plugs appear to be wrong. As the loom is from a truck I thought that a marine electrical loom may be more suitable. The loom would be stand alone – engine only – but with a fly by wire throttle pedal.

Do you have any ideas as to how to make this work?itasca-motorhome


Hi Francis,

Sounds like a fun project.

The inboard engine should have all of the electronics required to run mounted directly to it. The only wires needed to get it to run would be 12 volt power from a key switch (usually purple on the engine wiring) and a momentary start wire from the key switch (usually yellow/red). Coming from the engine, the gray is the tachometer lead, the light blue is the oil pressure, and the tan is the water temperature.

I don’t have experience with fly by wire throttle. Most of the Merc engines in that era were a straight cable to the accelerator. Good luck with that part.

If you can find it, ebasicpower has a ton of short engine harnesses and boat wiring harnesses that may make your adaptor magic easier to accomplish.

Good luck,


Wiring a Boat’s Carbon Monoxide Detector

Hi Kevin,

Could you please briefly outline location of carbon monoxide detector on a cruiser? Do I have to dedicate a unique circuit to the monitor.

My boat has two state rooms so I assume two monitors are required. My current plan is to wire directly to bus bar coming off battery and not to main electrical panel.

Thanks,carbon monoxide warning


Hi Sanford

I would refer to the CO monitor’s installation manual or the manufacturer’s website for the best location.

  • Size the wire for 3 percent voltage drop but do not use wire smaller than 16 awg.
  • Use circuit protection at the source of power.
  • If you are using a breaker, I like to use a push to reset style for co monitors instead of a rocker style to make it more difficult to turn off.

I also prefer to wire CO monitors and bilge pumps to have constant power and not be controlled through a battery switch, but sometimes it is not possible to accomplish this.

Hope this helps,

Keyless Boating


Thank you for all of the info that share with boaters.

I have a 1987 Sunbird II that for some reason every time you connect the battery the starter engages – even when the key is off.

I bought a new starter and solenoid but still does the same thing.

Could you please tell me what color wires go where? Also, any other solutions that you might have would be greatly appreciated.Starter motor



Hi Denia,

It sounds like there is a short between the battery power and the yellow/red starter wire.

I would remove the yellow/red from the key switch and try connecting the battery. If the problem goes away, test the key switch. If it is still there, check for an accidental short between the yellow/red and red on the engine.

Let me know what you discover,


AC Out


I have a 1989 SeaRay 280DA.

While plugged into a 110v source at my house, I plugged a battery charger into one of the boat’s 110 AC outlets. The battery charger shorted out, after that I cannot get power to any of the 110 ac outlets on board.

I have checked all the breakers in the main panel, and even replaced all of the AC outlets on board without success. I have checked out the on board battery charger and it is working fine.

Any suggestions?Sea Ray 280 DA



Hi Earl,

I would start at the source of power and make you way through the boat. If there is a bad connection, it may have voltage with a meter but not enough current to allow the device to work. When you are carefully working your way through the system, try turning devices off and on while testing with a meter to determine where the problem is.

If you have power at the source (the outlet on your house), you should be able to logically trace it through the system. It could be something as simple as a bad connection in your shore power cord causing all of the problems.

Hope this helps,


Self Starter


I hope you can help me. I am trying to figure out if my ignition switch is faulty.

It is a 4-post switch. One post says IGNI, the second says ACC, the third says BAT and the center one says nothing but there is one wire which goes to the starter solenoid. Marine Electrical ignition switch

Is the the center one supposed to go to solenoid? The reason I’m asking is because I am trying to find a short in my system and the engine tries to start by itself when I turn on my master switch without turning the key.

Please help.



Hi Mark,

The last wire should go to the starter solenoid, but usually passes through a neutral safety switch first.

I would start by removing the wire for the key switch, if that solves the problem, then replace the key switch.

The next area I would inspect would be the wires on the starter.

Hope this helps,