Power for watermaker

[crayiii]

I'm installing a 12v watermaker in the port engine compartment of our catamaran. The house batteries are all in the starboard engine compartment.

12v cables go through a positive and a negative cutoff switch in the starboard engine compartment then (after the positive goes through a large fuse) they run 15 feet into a electrical cabinet inside the boat where all the large breakers are then to the distribution panel.

If I run the watermaker cables from the cabinet, the run would be about 30 feet so the cables would need to be pretty large. I'm wondering what the right way to run the power cables would be.

Can I just run additional cables from the cutoff switches (with the positive cable going through the prescribed 30 amp breaker) in the engine compartment? Then the cable would be about a 10 foot run.

What's the right way to get power across?

[john61ct]

How many amps maximum load while making water?

[crayiii]

Originally Posted by john61ct

How many amps maximum load while making water?

I believe it's 15 amps. The manual calls for a 30 amp fuse.

[john61ct]

That's not much. Go to Blue Sea, download Circuit Wizard to calculate the gauge needed.

Use 2-3% voltage drop, ask Qs back here if any

[crayiii]

Originally Posted by john61ct

That's not much. Go to Blue Sea, download Circuit Wizard to calculate the gauge needed.

Use 2-3% voltage drop, ask Qs back here if any

My main question is where to pull the power. Do I tap into the battery switch? Do I add a cable to the big fuse on the positive cable from the battery? Do I run it from the closet that has all the breakers but is a long way away?

[Sailmonkey]

Originally Posted by crayiii

My main question is where to pull the power. Do I tap into the battery switch? Do I add a cable to the big fuse on the positive cable from the battery? Do I run it from the closet that has all the breakers but is a long way away?

I used a power tap fused directly from our house bank, run to a big solenoid that was controlled by a small wire from the house switch panel.

If you’ve got a battery monitor, be sure that your negative lead is on the house side of the shunt.

[Dsanduril]

There's no particular reason that you need to go to the main panel, that's just a convenience in having control all at one point. Personally I'd come off the switch or the main fuse so that you can still shut down everything with the main switch. But even that is preference, you could connect anywhere that is convenient as long as adequately fused. Just remember that if you connect on the battery side of the main switch you have yet one more connection to deal with if you need to disconnect in a hurry.

Somewhat as an aside, for this very reason we actually have three electrical panels on our boat; port hull, starboard hull, bridgedeck. I can cut off power to all with a switch at the house bank, but otherwise have big feed cables to each panel, then appropriate for load cables from each panel to consumers. It's 'cleaner' to me, but others prefer a single/central panel.

[kenbo]

Originally Posted by crayiii

My main question is where to pull the power. Do I tap into the battery switch? Do I add a cable to the big fuse on the positive cable from the battery? Do I run it from the closet that has all the breakers but is a long way away?

Don't add your new power cable to the big fuse. That fuse is sized for the cable running inside the stbd. hull. Tap off the battery switch, add a new disconnect then an appropriately sized fuse and go from there.