Wiring up an Auto Bilge Pump in 10 Simple Steps

by Ian Kuhl on July 2, 2016

in Chandlery, Featured, Marine Electrical Services, Shipwright Services

Having an automatic bilge pump on your boat or tender is an easy way to keep water out – as long as it is installed correctly.

Many people want to have an automatic pump but have trouble with the installation. If this sounds like you – you’re in luck! This article will run you through the basic installation of an automatic bilge pump.

You will need:

  • A Bilge Pump (of sufficient size – ask us if you are unsure) – A high quality brand that will last.
  • A Float Switch – Best to buy a quality brand. Don’t forget that it may save your boat one day!
  • A Fuse Holder (with appropriate size fuse for the pump size)
  • Some Marine Tinned Cable
  • Crimp Lugs to join cable and Ring Lugs to fit to battery
  • A 12v Battery

All of these parts are in stock at Franklin Marine. Be sure to check our prices before you buy from the City – you’ll be surprised!

Now… Here’s what you’ll need to do:

  1. Site the pump in lowest part of bilge, and site the float switch slightly higher.
  2. Put the fuse holder on the positive cable and connect it to the battery.
  3. Put the fuse holder in the battery box where it will be dry. Having a spare fuse taped to the lid of the box is helpful. Don’t fit the fuse yet!
  4. Connect the black (negative) wire to the battery.
  5. Run power cables aft to pump through a non-chaffing route.
  6. Connect the red or brown (positive) wire from the battery to one of the switch wires, then the other wire from the switch to the red or brown (positive) wire of the pump.
  7. Connect the black (negative) wire to the black (negative) pump wire.
  8. Make sure all wires are firmly connected and waterproofed with heat shrink tube or self-amalgamating tape.
  9. Fit the fuse and lift the float switch by hand switch to test it.
  10. Tie up the cable joins well clear of the bilge and keep all connections “high and dry”. 

Your wiring should look something like this…

As an extra, you may like to fit a bilge switch panel which will allow you to have both manual and auto operation.

To do this, you will need two positive wires to run from panel to aft supplying power from float switch and from manual switch.

There you have it!

That’s how easy it is to set up an automatic bilge pump!

If you have any questions about this guide – or any other electrical or mechanical system on your boat, please feel free to give our friendly team a call on (03) 6266 3768. They’re great at helping out over the phone and can arrange prompt delivery of parts if required.

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