Bilge switch short wires a usual

fisherman

fisherman

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Have after at least 22 years had to replace the bilge alarm switch, got a reed switch from Maplin OK, £14.99, but as ever the wires are too short (less than a foot) to get anywhere dry. A trailer junction box, plastic with rubber seal will hopefully do it and the bilge pump wires also, £3.49 from Trago. Does it never occur to them that 3 feet of cable would cost little more but make the job so much better?
 
Just installed a second pump and alarm on my boat, I agree the wires on the alarm,from force 4 are about six inches long, and the wires on the pump are not much longer, infuriating.
 
Last time I cut the wires to uneven lengths and soldered extra on, then slid a tube over the joint and filled with sikaflex, was OK but the live went at the switch end when water got in.
 
fisherman said:
Have after at least 22 years had to replace the bilge alarm switch, got a reed switch from Maplin OK, £14.99, but as ever the wires are too short (less than a foot) to get anywhere dry. A trailer junction box, plastic with rubber seal will hopefully do it and the bilge pump wires also, £3.49 from Trago. Does it never occur to them that 3 feet of cable would cost little more but make the job so much better?
Click to expand...

Note that reed switches generally cannot handle much current and, if you use a relay to buffer it, don't forget the diode.
 
The old Rule flapper switch on my engine bay pump was causing a major problem with my anodes allowing stray DC current leakage into the low lying salty bilge water, which in turn found its way outboard to the anodes via nearby metalwork and the bonding circuit. It was also difficult to locate the cause of the anode wear, and had it taken out a prop the cost would have been massive.

Replaced it with one of these ...

http://www.force4.co.uk/7588/Whale-Electric-Field-Sensor-Switch.html

Simple test for a electrically leaking bilge pump switch is to turn every thing off except the circuit to the bilge pumps. Disconnect the battery positive and measure for voltage drop between the Batt +VE and disconnected terminal. If there is no leakage current flow then the reading should be 0 volts. More details in Calder's tome.
 
It says max current 50w/0.5A. At 24v, 50W is 2A. Or, 0.5A at 24v is 12W. Will it melt? It's working today.[/QUOTE]

Probably will not melt but the bilge pump is an inductive load which can produce a large voltage across the contacts when they open resulting in them burning & failing prematurely. I suspect the ratings given are for a resistive load.
A simple snubber circuit (capacitor and small value series resistor) across the contacts will prolong the life. This is similar to the 'condenser' (capacitor) across car contact points.
I agree with Graham, a relay is a good arrangement.
 
Dabhand said:
It says max current 50w/0.5A. At 24v, 50W is 2A. Or, 0.5A at 24v is 12W. Will it melt? It's working today.
Click to expand...

Probably will not melt but the bilge pump is an inductive load which can produce a large voltage across the contacts when they open resulting in them burning & failing prematurely. I suspect the ratings given are for a resistive load.
A simple snubber circuit (capacitor and small value series resistor) across the contacts will prolong the life. This is similar to the 'condenser' (capacitor) across car contact points.
I agree with Graham, a relay is a good arrangement.[/QUOTE]

Aha. I see where you're coming from, but for 'pump' read 'alarm'. I will check the wattage of the bleeper and the bulb tomorrow. The pump is on a different, manual switched circuit. I don't believe in auto bilge pumps if possible to avoid, for all the reasons in #6.
 
fisherman said:
Hmmmm.
http://www.maplin.co.uk/p/assemtech-compact-float-switch-horizontal-mounting-cl25c

It says max current 50w/0.5A. At 24v, 50W is 2A. Or, 0.5A at 24v is 12W. Will it melt? It's working today.
Click to expand...

Those are very much cheaper on ebay (assuming they are identical) and recently they have been offered with a buffer relay.

The spec doesn't state whether the current rating is for AC or DC. Eventually (speaking from experience) the contacts will either burn or seize.
 
Graham_Wright said:
Those are very much cheaper on ebay (assuming they are identical) and recently they have been offered with a buffer relay.

The spec doesn't state whether the current rating is for AC or DC. Eventually (speaking from experience) the contacts will either burn or seize.
Click to expand...

I think you've missed the salient point: this is to switch the alarm only, a small bleeper and warning light. I will check their wattage today. The previous reed switch was much the same and lasted at least since I bought the boat in 1992, it didn't burn or seize, the wire fell out. I route the neg via the switch so no pos current near the bilge, will that help I wonder.
 
Aha. I see where you're coming from, but for 'pump' read 'alarm'. I will check the wattage of the bleeper and the bulb tomorrow. The pump is on a different, manual switched circuit. I don't believe in auto bilge pumps if possible to avoid, for all the reasons in #6.[/QUOTE]

I took your comment about the bilge pump wiring being in the same junction box as being wired into the switch itself. You are right, if it is merely to bleep and flash then it should be ideal for your purpose providing the items themselves are not too heavy on current.
 
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