Marine electrical questions?

June 28th, 2010 by Kevin Hannula

Marine Ac/Dc attempts to answer your questions about boat wiring and marine electrical techniques, concepts, and products. We get lots of mail from folks in mid-project or who are just curious about their boat’s electrical setup.

There are loads of post already on the site which we hope you will browse through. If you’re trying to track down info about a more specific category, please use the search box in the upper right of this page or check out the list of various subjects farther down on this page.

If you aren’t able to find the info that you need to complete your particular boat wiring project, please send us an email at boatwiring@gmail.com.

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

Posted in Battery Charger, Battery Switch, Boat Wiring, Bow Thruster, Circuit Protection, Corrosion, Cruisers, Gauge Panels, Harnesses, Marine Electrical, Navigation Lights, Pontoons, Runabouts, Signaling Devices, Switch Panels, Testing, Trolling Motors, Uncategorized, VSR, Wipers | Comments Off



Wipe Out

January 23rd, 2012 by Marine Ac/Dc

Kevin,

I have to replace a wiper motor which has only two wires and an “on and off” switch.

I’m going to replace with a AFI MRV #34000 which states I need a three-position switch. This would be very difficult to rewire though the windshield.

The vessel is a 1991 SeaRay 350. Is it possible to us the existing switch and boat wiring??

Gary

AFI wiper motor

Hi Gary,

If your current wiper has two wires, power and ground, connect the ground to the case on the MRV 34000 and the power to either speed 1 or speed 2 on wiper motor.

If your current wiper has three wires, power, park, and ground, connect the ground to the case, park (constant power from fuse or breaker) to the park wire on the wiper motor, and the switched power to either speed 1 or speed 2. Even though your new wiper motor has two speeds, you will only be able to control one.

Hope this helps,

Kevin

Posted in Boat Wiring, Cruisers, Electrician's Log, Marine Electrical, Wipers | Comments Off



Light Motif

January 17th, 2012 by Marine Ac/Dc

Hi Kevin,

Quick question.

I am going to buy and install sidewall lights for a friend’s cabin. The locations are prewired.

Could you please tell me if there are any specifications that I should be aware of? Since these will be running off the battery, do I have to get DC specific lights? Any recommendations as to the boat wiring?

Thanks,Vista is one of the top suppliers of marine electrical lighting for your boat wiring project

John.   

Hi John,

You will need to buy DC specific lights. You will also need to know if the system is 12 or 24 volts. The higher voltage lights will illuminate at the lower voltages, but will be dim. For example, 120v lights will operate at about 10% output if a 12v supply is applied. They would last forever, but would be dim. Too low a rating, they would be bright, but short lived.

They will be labeled in the form…12vdc…10 watt.

Hope this helps,

Kevin

Posted in Boat Batteries, Boat Wiring, LED Lights, Marine Electrical, Mood Lights, Pontoons, Rope Lights, Sailboats | Comments Off



Correct Cable

January 9th, 2012 by Marine Ac/Dc

Hi Kevin,

I’m redoing the boat wiring an my old 1978 Catalina 25 sailboat.

I need to know which gauge of marine electrical battery cable to use in connecting the batteries to the boat battery switches and the switches to the boat bus bars. The overall distance for the wire runs is no more than 48”.Boat Wiring Store offers a complete line of battery cables that are custom built for your boat wiring project

Thanks.

Brice

Hi Brice,

This will depend greatly on the loads.

If you have a simple DC system and no starting motors, then you could use 4 AWG battery cable. If you use these batteries to start an engine or you have a large DC load bank, I would go with at least 2 AWG battery cable.

Hope this helps,

Kevin

Posted in Battery cables, Battery Switch, Boat Wiring, Marine Electrical | Comments Off



Sailboat Rewire

January 2nd, 2012 by Marine Ac/Dc

Hello Kevin,

I’m beginning a large boat wiring project on my 38 foot sailboat.

I have purchased new marine electrical panels and switches, and am beginning the wiring plan.

I need to know how to properly support the wires. For example, is conduit to be used…wrap around protective sheathing? The existing boat wiring (which was automotive wiring), had large lengths of wrap around plastic protective sheathing that looked to be flammable.

Please advise.

Thank you,

Earl

Hi Earl,

Per the ABYC, American Boat and Yacht Council, boat wiring must be supported every 18″ and any loom must be self extinguishing.

My preference self-extinguishing, split loom with cable ties every 12-15″. Make sure to add cable ties on each side of marine electrical bus bars and modular connectors. Even though these terminals are required to resist a 6 lb. pull test, it is better to take the extra time in installation than waste your time troubleshooting.

FYI, usually a blue tracer line on the split loom signifies self extinguishing.

Happy wiring.

Please send pictures of your project.

Kevin

Posted in ABYC, AC Wiring, Battery cables, Boat Wiring, Cruisers, Harnesses, Marine Electrical, Marine Engines | Comments Off



AC System Ground

December 19th, 2011 by Marine Ac/Dc

Kevin,

Your Easy Add AC – Marine Shore Power looks fantastic. Just what I need to plug and play!

I need some advice on the green ground wire. I have a DC system. No engine on my sailboat. Want to add your AC shore power system.

Your instructions state to connect to my DC negative which in turn on most boats is connected to the engine which provides ground. How do I accomplish grounding without an engine? Seacock, ground plate?

Thank you,

JR

Hi JR,

I’m glad that you like our system. As you said, we designed it to be truly “plug and play”.

As for your question…

The green AC ground wiring should be connected to the negative side of your DC system. This provides a low resistant path to ground in the event of an AC to DC fault. Even though the 5 mA GFCI on the panel will trip long before the 30 dock main, we still need to have the green AC grounding wire to keep our friends at the USCG happy.

Hope this helps,Shock Warning Sign

Kevin

Hi Kevin,

Thank you for the prompt reply.

I’m still confused. Is it ok that the DC is not connected to an engine (no engine on my sailboat)? Do I need to connect my DC bus to a seacock or external ground plate?

Thanks,

JR

Hi JR,

If you have a grounding system on your boat wiring (ground plate, seacock, etc), it should be connected to the DC negative system. The AC grounding wire from your AC system should connect here as well.

This will help prevent your seacock from being energized by 110v AC with no low resistance path to ground.

Kevin

Kevin,

Just to get it straight —the seacock and the AC green and the DC negative all connected to the DC neg bus? The seacock which is is on the water side provides the low resistance path ?

Thanks in advance for your tolerance. BTW you make it an easy choice to purchase from your boat wiring store with such great tech advice!!

JR

Hi John,

The wire that connects the AC grounding wire between the AC panel and your boat’s grounding system provides the low resistance path to ground that will trip the breaker on the dock. Without this, in theory, an AC wire can accidentally come in contact with the seacock on your boat. Since there is so much resistance the water, the dock breaker will not trip due to the low current the seacock path to ground (through the water) is inducing.

If a swimmer comes near the seacock, they become a lower resistance path to ground (the bottom of the marina) and then become paralyzed by AC voltage present in the water.

The main GFCI on our panel protects far beyond what the main dock breaker can do.

Hope this helps,

Kevin

Posted in ABYC, AC Wiring, Boat Wiring, Cruisers, Galvanic Corrosion, Ground Issues, Marine Electrical, Runabouts, Sailboats, Shore Power, Shore Station | Comments Off



Masthead Wiring

December 12th, 2011 by Marine Ac/Dc

KevinAttwood is the world's top source for LED navigation lights

My boat wiring question relates to 12 volt LED navigation lights on top of mast that is 75 feet tall.

The power draw on the navigation lights is less than 0.5 amps each for the white LED anchor light and red and green combo light.

What size boat wiring should be used?

Is there a four conductor tinned wire in the US that is appropriate? In Europe there is an Italian brand tecnikabel. Does your partner marine electrical site offer something like that?

Thanks,

Mary

Hi Mary,

Attwood LED navigation lights are a great addition to any boat, but are especially suited for sailboats.

If you are trying to maintain a 3% drop or less, you can be up to 156 feet total wire (source of power to light and back to ground) if the light draws 0.5 amps and still use 16 AWG wire. At 0.4 amps this goes up to 195 feet.

Here is a link to my wire size calculator for future reference.

Ancor makes a great 16-4 jacketed, tinned cable that would work well for your application.

Hope this helps,

Kevin

Posted in ABYC, Anchor Lights, Boat Wiring, LED Lights, Marine Electrical, Masthead Lights, Navigation Lights | Comments Off



Columbia Rewire

December 5th, 2011 by Marine Ac/Dc

Hello Kevin,

I’ve recently became the owner of a Columbia 22 sailboat built in 1969. I’ve gutted the boat wiring from her and need to rewire.

I need bow port and starboard navigation lights and some minor interior lights she currently has a white masthead light at the cross tree and a transom light. Both of them seem to look fine however I would like to convert to LED for all the lighting.Attwood is the world's top supplier of navigation lights for boats

She also has in place a Guest battery switch

I’m considering buying everything that I need from your snap-together boat wiring site.  But, before I do, can you tell me everything that I will need?

I think I need to control three separate lighting systems

  1. The red and green bow lights
  2. Masthead and stern
  3. Interior lights
  4. Perhaps nav/GPS and cell phone charger?

Any help would be appreciated. Your snap together wiring system seems like a real timesaver, but I didn’t want to get the wrong parts.

Finally, do you also furnish instructions on how it all hooks up to everything including battery?

Thanks again

Peter

Hi Peter,

I would start with our smaller boat wiring harness. This will provide wiring for your red/green boat lights, your white, all-round light, and interior lights.

On your boat, I would combine this harness with our five switch marine electrical panel. This panel will provide switches for your nav/anc and stern lights along with your cockpit courtesy lights.

We have several navigation light kits that plug directly into our wiring harness. Simply choose the mounting configuration for your boat.

The installation is easy and instructions are provided.

I would keep the Guest battery switch in the system. The main power connection from your new boat wiring harness will connect to the battery switch to allow you to completely turn the power off when you leave your boat.

Hope this helps,

Kevin

Posted in ABYC, Anchor Lights, Battery Switch, Boat Wiring, Bow Light, Circuit Protection, Courtesy Lights, Cruisers, Horn, Marine Electrical, Masthead Lights, Mood Lights, Navigation Lights, Sailboats | Comments Off



Custom Marine Electrical Panels?

November 28th, 2011 by Marine Ac/Dc

Hi Kevin,

I found your sister operation, EzAcDc boat wiring on Ed Sherman’s site.

I am about to rewire my 42 foot ketch with new boat wiring and distribution/breaker panel.EzAcDc also has a complete kit to rewire you existing switch panels - a big part of any boat wiring project.

I have HF radio (35 A), water pump, sewage treatment (both 15A), VHF radio (8A)fridge (3A), plus the usual internal lights and external nav lights. No power winches or other serous current devices, other than of course the Yanmar 54 bhp starter battery and motor. I have a 300 AHr ships battery bank (3 x 100 AHr) and a 900 CCA starter battery.

Your marine electrical panels look interesting and also the boat wiring harnesses seem well made and should simplify installations.

Can EzAcDc supply panels suitable for larger numbers of circuits? What form do your harnesses take, can I get lengths custom made if I provide lengths?

Johnson

Hi Johnson,

At this time our partner sites, EzAcDc and Boat Wiring Store, do not produce custom switch panels and boat wiring harnesses.

Usually, when expanding an EzAcDc system, our customers purchase a fully wired marine electrical switch panel and then purchase either an unloaded switch panel or an unwired switch panel to install in conjunction with the fully wired system.

This give them the ability to have a second switch panel made from the same material and same switch style. We offer a complete line of tinned boat wiring and marine electrical connectors so they can custom wire the second panel to their needs.

Hope this helps.

Please let us know if you have any questions,

Posted in AC Wiring, Anchor Lights, Battery cables, Bilge Pumps, Boat Batteries, Boat Wiring, Bow Light, Bow Thruster, Courtesy Lights, Cruisers, Gauge Panels, Harnesses-Dash, Harnesses-DC, Horn, Marine Electrical, Masthead Lights, Navigation Lights, Switch Panels | Comments Off



Bow Light Always On

November 21st, 2011 by Marine Ac/Dc

Kevin,

I recently built a new marine dash panel for a used Invader Boat. I bought all new gauges and switches, but I’m having a problem with the new Attwood navigation lights. The bow light comes on when the switch is in both the anchor position and the navigation position.Attwood is the world's top manufacturer of navigation lights for recreational marine.

I used a Contura rocker switch, an on-off-on. Do I need to change to a double pole/double throw switch?

Thanks,

Seymore

Hi Seymore,

Please check out this post on navigation light wiring from our sister boat wiring site, Easy Ac/Dc. It will explain how to correctly wire both the switch that you purchased as well as a double pole/double throw.

Happy boat wiring,

Kevin

Posted in Anchor Lights, Boat Wiring, Bow Light, Cruisers, Gauge Panels, Marine Electrical, Navigation Lights, Switch Panels | Comments Off



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