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Author Topic:   Float Switch Wiring
Frank O posted 09-11-2006 07:48 PM ET (US)   Profile for Frank O   Send Email to Frank O  
After debugging of bilge pump problems, I've found that the Johnson 36152 float switch installed in the bilge of my 1995 OUTRAGE 21 (along with a Rule 1500-GPH pump) is busted. It appears this switch is no longer available, but Johnson makes another one called the 3615w that looks close to identical.

Two questions:

-- The float switch has three wires coming out of it. I assumed this was a simple single-pole, single-throw switch and was expecting two wires. What's the third one for?

-- The 3615w float switch doesn't appear to get a very good customer review (one star) on West Marine's website. As long as I'm changing this out, is there a float switch any of you like better that I might consider? I'd just as soon not replace the pump itself since it seems to be okay.

jimh posted 09-11-2006 11:47 PM ET (US)     Profile for jimh  Send Email to jimh     
I think that Johnson Pumps are sold as the Mayfair brand. I looked high and low for a website to get information on these float switches, but I could not find anything. My only guess is the switch is a SPDT, hence the third lead. What you would use that for is anyone's guess.

A pointer to the Johnson or Mayfair website would be helpful.

jimh posted 09-11-2006 11:53 PM ET (US)     Profile for jimh  Send Email to jimh     
Found it! accessories/accessories.htm

Chuck Tribolet posted 09-11-2006 11:55 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Another posibility is that it's a SPST switch with two leads
on one side. Run the single lead to power, or the "AUTO" side
of the SPDT bilge pump switch. Run one of the
two leads to the pump, the other side to the "YES, DAMNIT,
RUN THE PUMP!" side of the SPDT bilge pump switch (which
also has the pump pilot lite wired to it).


jimh posted 09-12-2006 12:00 AM ET (US)     Profile for jimh  Send Email to jimh     
Here are the instructions: pdf

It looks like the switch needs to be connected to the battery negative (black lead). The brown leads are the switch contacts, which are placed in the positive lead to the pump motor.

Frank O posted 09-12-2006 12:39 AM ET (US)     Profile for Frank O  Send Email to Frank O     
Thanks, yes I see in the wiring diagram that one lead from the swtich goes to battery ground. Seems odd for a switch to have a ground connection -- it's not as though it has a shielded case, does it?

Re my other question, is there a float switch that's more popular that I might consider going with instead?

Casco Bay Outrage posted 09-12-2006 01:03 PM ET (US)     Profile for Casco Bay Outrage  Send Email to Casco Bay Outrage     
I use Rule for pumps and float switches.

See 10001/263685/0/0/rule%20float%20switch/All_2/mode+matchallpartial/0/0

They are $10 less at other stores.

Frank O posted 09-12-2006 02:03 PM ET (US)     Profile for Frank O  Send Email to Frank O     
Thanks -- I see Rule claims the basic Rule-A-Matic is the best-selling float switch in the world.

Also, it looks as though the Rule-A-Matic Plus just has two wires hanging out of it, so I gather I can just treat it like a SPST switch and seal off that wire to battery ground that the Johnson switch wanted connected to itself.

Chuck Tribolet posted 09-12-2006 02:35 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
I think I'd put an ohm meter on each of the three pairs of
wires and see what happens as the switch turns on and off.


Frank O posted 09-12-2006 02:48 PM ET (US)     Profile for Frank O  Send Email to Frank O     
My thoughts exactly, Chuck.
Frank O posted 09-16-2006 10:38 PM ET (US)     Profile for Frank O  Send Email to Frank O     
Interestingly, I stopped by West Marine today, and the entire wall of float switches was bare. Their staff told me that all the switches had been "recalled" because they contained mercury. The only switch they had available was a West Marine house brand switch with a loose ball rattling around inside.

Sal A posted 09-22-2006 12:56 PM ET (US)     Profile for Sal A  Send Email to Sal A

Maybe worth a look....

Frank O posted 09-22-2006 05:53 PM ET (US)     Profile for Frank O  Send Email to Frank O     
Looks interesting, Sal. But my bilge pump setup is wired straight to the battery, so it will go on even if the boat's master power switch is off (boat's kept in the water). If that switch draws close to 1/4 amp when the pump's not running, that sounds like it'd run the battery down.

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