Battery switch ?
Engine, Tach & a switched (un-grounded, plastic ) bilge pump
Is it better to switch the - (Neg) side
The + (pos) side.
Catipillar switches the Neg
When working on your auto, many safety steps say disconnect the - (neg) lead.
Makes sense to me to switch the - (neg) on an aluminum boat. ?
reasons not to?
Bilge pump is grounded to negative, I think you mean to say its not bonded big difference.
Originally Posted by mudbuddy
Negative cable interrupt is not the preferred way to wire a marine battery switch. Electrons flow from Positive to Negative. (the reason we call it ground is because electrons flow towards Earth. Ground = Earth, see?)
You want your interrupt switch on the positive cable. Use at least 4 AWG, or 2 AWG if you need to mount the switch away from the battery box. Tinned marine grade wire is the best way to go for longevity and reliability, not to mention USCG and ABYC standards.
Since you are only wiring an interrupt switch and not a dual battery switch it will be an easy install for you. Negative still goes to systems ground, just like whatever you have now. You will need a new Positive lead to go from the battery to one pole on your switch, and the other pole on the switch gets connected to your existing positive. Done deal.
Bilge pump is a basic one. 2 wires
Originally Posted by SockeyeOne
+ & - (neg), no ground.
DC current: Was taught electrons are - (neg charged), flow - (neg) to +
I wired it to disconnect the +.
#4 AWG , 8 ft to the engine battery wiring harness.
I think you are within the proper specs for wire gauge and distance with the amperage you are drawing. Nice job getting it all wired in.
With regards to your bilge pump. No worries there. Thats pretty standard configuration in your type of setup.
Its important to remember when we speak about the negative side of a circuit in a marine application that is what we are calling the ground. What you think of as ground in AC electric is just the free floating neutral and ground which can be connected to shore AC in a marine system if the vessel in question has an AC system on board.
Bonding is basically tying all of your metals to a cable that connects to a scarificial anode (usually zinc in salt or magnesium in fresh H2O) that is located below the waterline on the exterior of the vessel. Usually this is a plate about an inch and a half thick and of varying dimensions depending on the size of the boat. Since you have a plastic body bilge pump there is no need to bond it, its plastic and wont create any galvanism.
You don't really need to worry about 'grounding' your DC systems in a boat because the negative side is your ground.
If you would like to do some further research on marine electrical and bonding systems and how to maintain them, I suggest the following link as a bit of a 'crash course'. Its full of all kinds of interesting information and will help illuminate some of the foggy areas and misconceptions many boaters have about their marine electrical systems. I know it helped me a lot when I went to upgrade the AC system in my boat with GFI's. I have a lot of wire, two 30 amp AC service entrances, and a 6.5 kw GenSet on my AC side alone. I needed a bit of technical information before I felt comfortable messing with it, and in the process even learned some things about my DC systems that I didn't know before. I hope it will help you wrap your mind around these complex issues as well.
Happy boating, and congrats on your new battery switch install.
on 20/72 Sea Ark