Electrical wire gauge and colors for a boat?

[Al Gagnon]

While rewiring my boat for bilge pumps and hi water alarms, I discovered the boat uses white as the hot sometimes. I found the trim tabs are reversed from Port and Stbd. The Previous wire that was feeding the 4 amp bilge pump and the stern 20 amp bilge pump were wired in parallel and fed from a 15 amp breaker and had #16 gauge wire coming off of the breaker. When either float was closed both pumps operated. Now I know why the pumps were triping the breaker and the wires have turned black from over heating. The auto pilot has #16 feeding the auto pilot system and they used both wires so it could carry the amps to the auto pilot. I am going with the correct wire size and use tinned wire. I know that sometimes it is cheaper to run wire to a switch and have black going out from the breaker and use the white coming back and then off to the load. When ever wiring a boat make sure you understand that colors of wire can be black and white, black and red or now the new color is red and yellow. I am not bad mouthing the Blackman Electricians or Blackman boats Co. or a previous boat owner. Sometimes you do what is needed to make things work. Just letting people know that you never know what someone has done to the boat after it come from the factory. Sure glad I did not short out my auto pilot, trim tabs or anything else. I now need to go through the Volvo panel and verify all compn ets are clean and tight. Just having fun accomplishing things on my boat. Great feeling when you find out something is wrong and you can make it better.

[NoSlack]

The great thing about re-wiring a boat, you'll know exactly how everything works and were it is if you ever have problems out at see. You right about a lot of creative wiring being done after a boat leaves the factory.

Mike

[Knot Now]

Al
It sounds like someone replaced your sten pump with a monster....Rule's biggest pump (3700 GPH) has a 20 amp draw. I think mine is a Rule 1100 that draws 5 amps..might be smaller.
That pump also requires a special float valve. not the regular one....The wiring that the floats activate both pumps is correct. I would suggest you go back to the correct size pump in the stern.
If you want the additional capacity of the 3700 GPH wire that pump in with new wire to a separate breaker....no need for a float switch....just flip the breaker.....This is an example of bigger is not better.

Your Trim tabs may not have been reversed...they act crosswise so using the port trim tab controls the bows starboard side.

[Al Gagnon]

Thanks for your input Mike and Phil. Phil, I figured the trim tabs were ment to be that way so I left them as is. The rule 3200, that was a 20 amp, Rule upgraded to the new 3200 or 3400., forgot already, they are now 25 amp and I did install there special float switch. I wanted each bilge pump to be independant of each other. I drained the antifreeze solution, picked up another sender from SDMX, but incorrect threads. So I cleaned the threads and brass washer and reinstalled it. Seams to be operating a little closer to the stb engine now, so I will ck it out next run. The Stbd engine seem s to run hotter at highr rpms. I found that there is a tee in the line that goes into the air pre-cooler. It was used as a overboard visual to verify the pumps were pushing water into the engine. Im wondering if at hi rpms too much water is going out the overboard instead of what is needed for the engine. I am going to plug it off next time and see if it runs cooler at hi rpms. Both engines are very close to each other in regards to temps. Used the temp laser gun and each engine was with in a few degs. Main heat exchange had the largest delta T across the unit. So forward and onward. Thanks again for th efeed back.

[DOGHOUSE26]

Al,

On DC Electrical Systems BLACK IS ALWAYS THE GROUND, unlike AC Electrical Systems, That is why you see the white as the hot or positive lead. Don't make the mistake of mixing your black and whites up it just keep the black wires grounded.

[Zarco]

Rewired many boats. Most guys not familiar with a 12v system will use black as power.big nono in a 12v system. I use the national wire color code and wired my boat accordingly. All tinned marine wire with
heat shrink waterproof connections.