Bilge pump polarity

[pcatterall]

Just installing an electric pump ( as none fitted on 'new' boat) I am fitting a 2000 gph pump and a manual/auto panel with alarm ( so two float switches upper one doing alarm)

The pump diagram shows positive through float switch to pump and the panel wiring shows negative is used through float switch to pump.

As long as I get the actual pump polarity right does it matter??

Thanks as ever!

 

[ostell]

If water wasn't involved I would say it doesn't matter. However I would do all switching on the positive side.

 

[nimbusgb]

If the negative side is switched you have the pump floating at 12v. If water gets in to the electrics then the potential (sorry ) for serious electrolysis is high.

Perhaps not the end of the world provided its contained to the bilge sump on a glass boat but if it gets up to the level of underfloor fittings, through hulls etc it could be really bad.

 

[lovezoo]

As others have said the negative side of the bilge pump should go to battery negative and the positive side should go through the float switch and a fuse to the positive side of the battery. Don't wire this through the isolator as it should always be on.