No announcement yet.

Wiring help

  • Filter
  • Time
  • Show
Clear All
new posts

  • Wiring help

    Going to be redoing most of the wiring under my center console. New battery switch, negative bus bar, terminal bar, and battery cables. What size wire do I need to go from the common on the battery switch to the switch panel? I believe it’s has a 10awg now. It’s only about a 3ft run. I was thinking about upgrading to 8awg. The vhf cuts off when I start the motor, and lights flicker when I use the washdown. I attached a photo of the panel. I know I won’t be using everything all at once but want to make sure it’s getting enough power.

    Click image for larger version

Name:	4D1C615A-FB22-4DF2-A484-E7BA5382169E.jpg
Views:	92
Size:	162.3 KB
ID:	560147

  • #2
    I would say that it depends a bit on which loads you want to be able to run together without voltage issues and also how you are planning to wire things up. Are you running a single battery for start and house loads combined or do you have two batteries that are split between start and house?

    Is you panel prewired so that you add power to one terminal and connect the loads to the appropriate switches to make it work, or do you need to run wire from a buss bar to the fuses and then to the switches?

    As to your question, for wire runs up to 6ft, which includes both the power and ground wire lengths, the following wire gages can support the following current flows:
    10AWG 30A
    8AWG 40A
    6AWG 70A
    4AWG 100A

    Google has lots of examples of wire selection charts, but here is a good one from a reputable source:
    Engineering high quality marine electrical components for safety, reliability and performance

    As to your comment about the VHF turning off when you start the engine, I would consider a two battery system separating house and start loads. If you don't want to or can't do this then consider turning off your electronics before engine start as the voltage fluctuations are hard on them.
    Toronto, Canada
    76 Mako 23


    • #3
      I do have two batteries with a 1 2 both off switch. The panel was pre wired with a pigtail, then to a terminal block, then to the device.
      Click image for larger version

Name:	339F1733-C889-4914-803A-EFFAD84B05DE.jpg
Views:	53
Size:	313.6 KB
ID:	560150


      • #4
        I guess my question is will it hurt the panel if I replace the 10awg wire with an 8awg for the power from panel to battery switch?

        when I’m fishing at night with the motor off I’m running fish finder 3amp, vhf 5amp(when transmitting), radio 10amp, anchor light (don’t know exact draw), occasionally a led spotlight for short periods of time (don’t know exact draw), and occasionally the wash down pump for short periods ~10 amps. If I have all these devices on at once, wouldn’t it blow the 30amp fuse? Would it be better to go to 40amp breaker and 8awg wire?


        • #5
          Originally posted by StrikeZone212 View Post
          I guess my question is will it hurt the panel if I replace the 10awg wire with an 8awg for the power from panel to battery switch?
          I see no reason why it would hurt the panel if you replaced the power wire.

          Toronto, Canada
          76 Mako 23


          • #6
            you'll be fine running a larger gauge wire.

            Washdown pump and engine starting are large loads, so you may have some wire sizing issues there. Are the batteries in the console or under the transom boxes? If they are in the console what size POS and NEG are running back to the motor (s)?


            • StrikeZone212
              StrikeZone212 commented
              Editing a comment
              My batteries are in the console and have 2awg wires for both positive and negative. And my wasdown push draws 6 amps at max