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Author Topic:   Automatic Bilge Pump Wiring WITHOUT Switch
whalerajm posted 05-05-2005 12:04 AM ET (US)   Profile for whalerajm   Send Email to whalerajm  
I just picked up an Attwood Sahara 500 Automatic Bilge Pump for my 1975 Montauk. In the past I've used a manual pump and just clamped onto a battery when I needed to pump out.

I don't need/want a switched pumped (auto/maual on/off)... I was hoping to have a pump I could connect to power source (aka battery or terminal block)in automatic mode. Switched pump in a Montauk seems lake major overkill to me.

Can anyone tell me how to wire this pump so it is always in auto mode when I connect to battery...It seems the Attwood folks don't tell you how to do this in their documentation...apparently they want you to buy the "required" switch after you've bought the pump.


LHG posted 05-05-2005 03:21 AM ET (US)     Profile for LHG    
Just run the two wires directly to the battery posts. Be sure to buy the right size ring terminals. The Attwood auto pump in the splashwell of my 25 Outrage full transom came wired exactly the same way.

The only reason you would want an on-off switch is to override/disable the auto float switch feature, usually to prevent pump cycling if water is constantly rising in the bilge, such as if you want to let boat self-bail.

Clark Roberts posted 05-05-2005 07:07 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Advise that you install a fuse (appropriate amperage as recommended by manufacturer) in the positive wire at battery! Happy Whalin'... Spruce Creek Navy
whalerajm posted 05-05-2005 07:54 AM ET (US)     Profile for whalerajm  Send Email to whalerajm     
Thanks for input guys. I should have been more specific with my question...

The pump has 3 I do anythng with the 3rd wire or just not connect it? ...if so which wire do I not connect?

It sounds like you're saying that pump "default" mode will be automatic once positive/negative leads are connected to power source.

Sorry if these seem like dumb questions...Answers may seem obvious once I start palying around with it.

knothead posted 05-05-2005 08:57 AM ET (US)     Profile for knothead  Send Email to knothead     


Your pump has 3 wires, one is the ground that goes to the negative terminal. One is a positive feed that goes to the float switch which activates the pump in the automatic mode. You can wire this to the positive terminal for full time auto mode OR you can wire it to a switch so that you can control when the pump is in automatic mode. The other wire is a positive feed that bypasses the float switch and turns the pump on. This is usually wired to a switch so that you can manually turn the bilge pump on and off when you want.

I don't have a copy of your pump, so I can't tell you which wire is which, but that is typically how they work.

best regards---knothead

Joe Kriz posted 05-05-2005 09:40 AM ET (US)     Profile for Joe Kriz  Send Email to Joe Kriz     

Here is an easy way to figure out which wire is which wire if you've lost your wiring diagram.

1. Connect your ground wire to the battery

2. take either of the other 2 wires and touch it to the positive terminal;
If the pump comes on, this is the wire you Don't want.

3. Use the wire that does not turn on the pump. Install an inline fuse and fuse holder as Clark mentions.

Now, you can turn the pump upside down and it should activate the float switch. (just like it would when water raises the switch). Put the pump back in the sump and you should be ready to go.

The remaining wire is just capped off and not used.
If you ever want to disconnect your pump for any reason, just remove the fuse and put the fuse holder back together without the fuse.

whalerajm posted 05-05-2005 10:18 AM ET (US)     Profile for whalerajm  Send Email to whalerajm     
Thanks guys...all good advice (as usual)...
Sneddog posted 05-05-2005 03:19 PM ET (US)     Profile for Sneddog  Send Email to Sneddog     

I've got the exat same pump in my splash well. The striped lead is the override of the float swith i.e. manual on. The solid red lead is for "auto" i.e. functioning off the float switch.



Johnny Stugots posted 04-16-2007 10:53 AM ET (US)     Profile for Johnny Stugots  Send Email to Johnny Stugots     
Can someone tell me what Fuse Amp. I will need for the Attwood Sahara bilge pump and how to wire it. Thank you
RLSmith posted 04-16-2007 06:32 PM ET (US)     Profile for RLSmith  Send Email to RLSmith     
The Attwood web site shows specifications for each pump that include the current draw and recommended fuse size. For example, at nominal 12V the Sahara S500 draws 1.2A with a recommended 3A fuse.

Johnny Stugots posted 04-17-2007 09:27 AM ET (US)     Profile for Johnny Stugots  Send Email to Johnny Stugots     
Thank you
bob1008 posted 07-22-2007 08:42 PM ET (US)     Profile for bob1008  Send Email to bob1008     
I have a brand new Atwood Sahara pump and a new switch. I cannot get power to the pump, Although the switch light does light in the manual mode. My question is as follows:

I have (2) batteries connected to a Perko 1-2-all-off switch.
The Sahara pump is wired direct to the battery.
The Perko battery switch is OFF.
Since the pump is wired directly to the battery, I'm assuming that the position of the Perko switch does not make a difference and will not affect the bilge pump.
Is this correct? Please excuse me if the answer is obvious. This bilge installation is driving me crazy and I know that I'm missing something.

jimh posted 07-23-2007 08:08 AM ET (US)     Profile for jimh  Send Email to jimh     
jimh posted 07-23-2007 08:10 AM ET (US)     Profile for jimh  Send Email to jimh     
If a device is wired directly to a battery, it is not possible for the setting of other controls and switches which control the battery distribution to affect the device.
pglein posted 07-23-2007 04:16 PM ET (US)     Profile for pglein  Send Email to pglein     
Doesn't anyone ever read installation manuals anymore?
Ferryman posted 07-24-2007 04:39 PM ET (US)     Profile for Ferryman  Send Email to Ferryman     

Only when all else fails.

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