Help! Bilge pump & float switch wiring

elv_1986

elv_1986

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Help, I need someone good with electrics!
I have a bilge pump, a float switch and a 3 way (on-off-on) switch..

My plan was to wire this up like this:

Left hand on position was 'auto', on the float switch

Off was all completely off

Right hand on position was switching the pump on

Now after some thought i'm not sure if this is possible, can anyone shed any light on if this will work or not?

Thanks!
Louis
 
elv_1986 said:
. . . . Left hand on position was 'auto', on the float switch

Off was all completely off

Right hand on position was switching the pump on

Now after some thought i'm not sure if this is possible, can anyone shed any light on if this will work or not?

Thanks!
Louis
Click to expand...

Hiya Louis, yes it is certainly possible but it would depend on your wiring capabilities more than anything else. I presume the switch has three spade terminals, is a rocker switch and from your description you are mounting it horizontally (left position, centre and right position)?

A battery live feed to the centre terminal on the switch which is then 'diverted' either right or left.

The left terminal on the switch goes to the float switch wiring at the pump.

The right switch terminal will need to go to the other side of the pump float switch (in effect by-passing the float switch).

The final wire of the pump returns to the battery to complete the circuit.

If you need the switch to operate 'the other way' with the switch positions reversed, reverse the left and right wiring on the back of the switch leaving the centre wire where it is. :)

Ring me if you like?

ps: ** The switch HAS to be able to handle the current demand of the pump **
 
Last edited:
Hi lenseman,

Thank you very much for replying, your presumptions are correct.

So, the wire from the left terminal goes to the float switch - does the other wire from the float switch then join with the brown +ve wire on the pump?
And the wire from the right terminal also joins to the brown +ve on the pump?

Louis
 
elv_1986 said:
Hi lenseman,

Thank you very much for replying, your presumptions are correct.

So, the wire from the left terminal goes to the float switch - does the other wire from the float switch then join with the brown +ve wire on the pump?
And the wire from the right terminal also joins to the brown +ve on the pump?

Louis
Click to expand...

You have a pump, a separate float switch and a three way rocker switch and a battery.

The pump has two wires coming out.
The float switch has two wires coming out.
The three way switch has three wiring positions.
The battery has two terminals.

OK
.

PUMP
Join one of the pump wires to the float switch and the other to the battery negative terminal.

FLOAT SWITCH
On the float switch, one wire now goes to the pump. The other wire on the float switch goes to one of the outer spade terminals on the rocker switch.

ROCKER SWITCH
One of the outer spade terminals already goes to the float switch. The other outer spade terminal goes to the connection you made when you joined the pump to the float switch, (basically it goes to the other side of the float switch, by-passing it for manual operation. This now is a three wire joint. The centre spade terminal goes to battery positive (preferably via a fuse of the correct rating as the pump current).

If necessary, draw out the above instruction and it should become clear? :)

ps: Probably a "Rule" Pump with a BROWN wire and a BLUE wire? The Blue wire goes to Battery and the Brown wire goes to the Float Switch.
 
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Slightly off topic perhaps, but out of curiosity why would want to be able to completely disable the pump so that it doesn't operate under any conditions?

I would think it's a lot more common to have the float switch permanently enabled and just add a manual switch so that you can manually turn the pump on if desired...
 
lenseman said:
Possibly so that it can be turned off if the pump or float switch needs servicing or whilst the boat is out of the water on a hard standing? :rolleyes:
Click to expand...

Fair enough... the question was asked from a perspective of wishing to learn, although I might not have got that across :D

I can see that it would be slightly more practical than manually isolating the pump from the battery if you want to work on it.. but could it add the potential to accidentally disable the pump completely when otherwise you'd want it operable?

Again, apologies for the Fred Drift.. and yes, I know this is starting to go just as predicted by this thread http://www.ybw.com/forums/showthread.php?t=292999 :D

Cheers

Paddy
 
scan0110.jpg
 
paddy01 said:
. . . . . but could it add the potential to accidentally disable the pump completely when otherwise you'd want it operable? . . . . .
Click to expand...

Very valid point and no problems with the question at all. :)

A green LED plus a 1k2Ω resistor (in series) across the lead from the rocker switch/float switch with the other end of the LED/resistor combination connected to the blue wire (pump to battery) will indicate that the pump is 'live' and switched to 'AUTO'.

:)
 
lenseman said:
Very valid point and no problems with the question at all. :)

A green LED plus a 1k2Ω resistor (in series) across the lead from the rocker switch/float switch with the other end of the LED/resistor combination connected to the blue wire (pump to battery) will indicate that the pump is 'live' and switched to 'AUTO'.

:)
Click to expand...

Ah groovy, I'll squirrel that nugget away...

And now we return you to the scheduled programming..:o
 
Brilliant response!! Thank you, everyone. I now understand exactly how to do this. Have done a little drawing so now all that is left is to connect it all up :)

I wanted to be able to completely turn off the pump for servicing/hard standing as said, also if you have oil/mess in the bilges for some reason its not a good idea for the pump to start pumping it all over the side :S

I like the idea of having light too, might have a play at fitting that. It would be a great way of glancing over to the dash to check the pump is on auto.
 
Personally, I would prefer to have a light indicating that the pump was running. This would remind me if I had left it switched on manually and, more important, tell me if I was taking in water and the pump was running automatically.

Having a light on whenever the pump was set to automatic would also cause a small current drain for most of the time.
 
paddy01 said:
Slightly off topic perhaps, but out of curiosity why would want to be able to completely disable the pump so that it doesn't operate under any conditions?

I would think it's a lot more common to have the float switch permanently enabled and just add a manual switch so that you can manually turn the pump on if desired...
Click to expand...
I agree - given that your boat can sink if the bilge pump is accidentally left in the off position, the advantages don't seem to outweigh this risk.

I would just wire the pump direct to the battery via a fuse.
 
I agree with what you are saying, but I would still like to have a manual on switch, incase the float switch fails

One of my bilge pumps has a built in float switch, it even has a 5 second run period after the switch is off to empty it of water. A very good idea!
 
You can do what you want to do without including the option of manually switching the whole thing off. I can't quote stats but I would think most boats do it that way.

The bilge pump is run (fused) directly to the battery (bypassing any battery isolation switches) so that it always will operate if the float switch activates and then a manual switch is added in parallel allowing you to manually activate the pump if the float switch fails etc.

Either way have fun, I love little projects like this :D
 
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