Wiring an "Always On" circuit

[cpedw]

Wiring an \"Always On\" circuit

I am fitting an automatic electric bilge pump into my new (2nd hand) boat, a Westerly Falcon. It's my reasoning that this should be left switched on when the boat is unattended but everything else should be off.
There are 3 batteries, 1 for engine and 2 domestic, and 2 main battery switches, engine and domestic. There is also a charge controller, TWC I think.
Should I connect the pump directly to a battery (via its own switch and fuse) and if so, would that be a domestic or engine battery? Does it matter?
Thanks for your thoughts.

Derek

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[tr7v8]

Re: Wiring an \"Always On\" circuit

Personal thoughts are:-
Connect direct to the domestics via a fuse and an accessible switch.

Jim
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[oldharry]

Re: Wiring an \"Always On\" circuit

Connect it with its own switch and fuse to one of the domestic batteries. Not the engine battery, as if the float switch stick 'on' (it does happen) the battery will become discharged...

If you have one of those 2 way switches allowing manual or auto operation, conect it so that 'auto' is fed directly from the battery, while 'manual' is fed via the battery switching to avoid it being left on accidentally.

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[pvb]

And...

Good advice, and remember that the fuse should be as close to the battery as possible. Probably the best fuses for this type of use are the blade-type automotive fuses. You can get fuseholders for these from <A target="_blank" HREF=http://www.indexmarine.co.uk>Index Marine</A>.

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[Trevethan]

Re: Wiring an \"Always On\" circuit

I have done much the same as TR7V8, running straight from batter via a fuse to a four way panel.

Means I have 3 spare switches that could power gas alarm or carbon monoxide alarm for example.

I plan to run one to a really low poer LED that will act as a courtesy light, making getting on board the boat on a dark night a little easier.

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[tr7v8]

Re: And...

Whilst you can get waterproof blade fuse holders, you can get car type cartridge fuse holders that are truly water proof. Mine are a sicky shade of yellow and push together.

Jim
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[bedouin]

Re: Wiring an \"Always On\" circuit

I don't think I would wire the auto and the manual to different panels. In most cases the auto switch will also cause the "auto" wire to be connected to the "manual" wire (not always) and that could end up powering the whole switched panel through the bilge pump

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[LadyInBed]

Re: Wiring an \"Always On\" circuit

It is also a good idea to put a lamp/LED circuit across the pump so you have a visual indication that the pump is running. It is normally impossible to hear a pump with the engine running.

The 'Manual' switch which just shorts the contacts of the float switch will be seperate from a battery on/off switch (and fuse). I would not bother with the battery on/off switch, I would just have a fuse in line to the battery, as pulling the fuse turns the circuit off.

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[Trevor_swfyc]

Re: Wiring an \"Always On\" circuit

Your questions have been answered but I wonder if a bilge pump left on would be something that may give you peace of mind, but in reality would just delay sinking by 12 hrs. My theory being that if its a weep then no harm, if its a valve left open and a pipe splits shes going down bilge pump or no.
Its a bit like the theory that people drive more safely with no seat belt, so I double check all valves are shut before leaving the boat.

Any examples opinion from the forum regarding this?

Trevor


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[tr7v8]

Re: Wiring an \"Always On\" circuit

Understand what you are saying, but A. it is a condition of my insurance that I have an auto bilge pump and B. I remember a few years agobeing on a hire narrow boat and waking up in the middle of the night hearing a pump running which turned out to be the bilge pump! Was only a heavily weaping stern gland bt at least we were able to get the boatyard out toot suite to fix it.

Jim
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[anabel]

Re: Wiring an \"Always On\" circuit

Aoto bilge pumps often very necessary on timber boats, especially for some days after launching (until timbers have closed up). On grp craft they may comply with insurance and give you some peace of mind if you have to leave it afloat unattended for some time. However if a valve/skinfitting fails they certainly wont save your boat. It wont be able to handle the ingress of water. And if it could the battery will eventually fail. For slight leaks it will be ok. (It would be better to try to cure the leak). All skin-fittings below the waterline should have TWO s/s jubilee clips fitted. Check these each season before launching. It is a good idea to make a list of ALL the below w/l skinfittings and their exact location. Keep this list handy. In the event of flooding you will know exactly where to look for problem. Connect pump to domestic battery.

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[pvb]

Re: And...

Shouldn't be a lot of water in the battery box!

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[tr7v8]

Re: And...

Depends where they are, my batteries are 8inches off the bottom of the boat, on the starboard side of the engine bay (and not at present in battery boxes). Twill be very damp at least so mine is going to have a decent waterproof fuse. May not actually be water in the battery box but their will be various gases etc, so everything helps.
Always belt and braces must be my Avionic training!

Jim
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[bryantee]

Re: And...

Its good to have a led light ,so you know if the pumps running,its better to have a siren wired into the float switch,
If your motoring,then you will know as soon as the pump fires up.maybe the exhaust water is leaking into the bilge? if its in the marina ,especially at night some body may just hear,before its too late. Have the siren wired into the automatic feed not the manual side.

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[tr7v8]

Re: And...

The pump I am fitting is the fully auto Rule one so unable to know when it's on. It has electroinics inside which spin the impellor ever 2 1/2 mins and if it senses resistance pumps till it clears. I have another manual and an electric so this one is just to keep the ins. co. happy. Will probably put utlet for this one adjacent to cockpit so I should hear water splashing.

Jim
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[cpedw]

Re: Wiring an "Always On" circuit

Many thanks to all for your contributions.
The consensus seems to be to wire to the domestic battery via fuse and switch. Many favour an additional warning light.
I take the point that this can't cope with a serious failure when no-one is aboard, like a skin fitting coming away, but it would give an early external warning so someone else, if they are around and of a kindly disposition, could do something to help.
Thanks again,
Derek.

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[oldharry]

Re: Wiring an \"Always On\" circuit

Dont quite follow that one Bedouin. If its wored correctly I cant see how the auto feed can energise the switched board. Using the conventional diagrammatic for a two way switch, feed to the pump goes from the centre, and the 2 battery sources to the opposite 'ends', so that they would always be isolated one from another regardless?



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[bedouin]

Re: Wiring an \"Always On\" circuit

The autoswitch I've got is a single pole normally open switch. The "automatic" feed goes to one side the of the switch, and the bilge pump connection goes to the otherside - which is where the "manual" feed also connects (it has to be that way unless the auto switch is SPCO).

So if the auto connection is live, and the switch closes, that connects 12V to the manual connection. If the manual connection is also switched on on its switchboard then you are in effect feeding the "domestic" switchboard via the "always on" connection and the bilge pump switch &c.

IMHO the best way to wire this is with a SPDT centre off switch, with one latching and one non-latching connection.

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