How to wire a bilge pump? We show how to wire a 12V bilge pump float switch with a manual override.

How do you wire a bilge pump float switch? We show how to wire in a manual 12V bilge pump with a float switch, allowing the bilge pump to automatically activate when there is water in the boat bilge, but in this method we can override the float-switch in case of malfunction. Whether you have a Rule bilge pump, Whale bilge pump or another make, the wiring process is much the same. If you have an automatic bilge pump, then it already has a built-in float switch, but in this guide we focus on wiring a separate float switch with a manual electric bilge pump.
In the wiring installation of the 12V bilge pump the key elements are the 12V supply, a suitable fuse for protection, the float switch (which will be installed in the bilge), and a separate switch which can activate the bilge pump manually in the case of failure of malfunction of the float switch. In a previous video we wired the manual switch in series with the bilge pump float switch (which has its merits) but in this alternative method we wire the manual switch in parallel with the float switch, which has the benefit of allowing a manual override. Of course it would be quite easy to wire in a second manual switch to allow you to isolate the circuit in any event, we will leave that additional feature from this video, but will come back to that in a later more sophisticated setup with a main switch panel and master isolation switch
The basis of this electric bilge pump installation and float switch wiring is that there are two switches connected in parallel. In an ideal situation the bilge pump float switch keeps on doing its job and turning on the bilge pump when ever this is enough water in the bilge to trigger it, but in reality there are a couple of ways at least that things could malfunction. One is that the float switch could have some kind of internal failure with its electrical contacts. The other thing that might be more likely is that some debris in the bilge (eg a stray piece of rope, or a fender) could get lodged on top of the float switch and stop it rising with the water level.
The bilge pumps and float switch featured in this video can be purchased from the following links:
1100GPH Manual Bilge Pump: www.boatfittings.co.uk/p/12v_...
Bilge Pump Float Switch: www.boatfittings.co.uk/p/bilg...
A simple electric bilge pump comes with two wires, a positive and a negative wire. The impeller of the bilge pump is designed to turn in a specific direction, therefore it is important that the positive and negative bilge pump wires are connected the correct way round to their power supply. Any bilge pump should be protected by a suitable fuse, typically in the range 5Amps to 15Amps, but check with the instructions for your particular pump. In this guide we show you how to wire a 1100 gallons per hour bilge pump with a bilge pump float switch.
Starting from the positive 12V feed, we have the protective fuse (in this case a 5Amp fuse), this is connected to one of the wires from the bilge float switch (it doesn’t matter which). The other wire from the bilge pump float switch is then connected to the positive wire from the 12V bilge pump itself, this completes the positive side of the circuit. For the negative side of the bilge pump wiring, the negative feed wire is connected to the negative wire of the bilge pump. This circuit is then added to by putting a bypass wire from the positive feed to the bilge pump positive wire, via the manual override switch.
When connecting bilge pump wires, the connections should be kept in the dry. Where the wires enter the body of the bilge pump housing, the wires are sealed and the bilge pump itself can be fully submerged. Joints in the wiring, or connections to fuses and switches however should be kept safely above the bilge water level, or utilise waterproof connectors.
When choosing the position of the float switch, it should be approximately at the same height as the bilge pump, or a few cm higher. If the bilge pump float switch is too high then it will not be activated until the water has risen quite a long way. If the float switch is too low compared to the bilge pump then there would be a point where the float switch would have been activated but the water level would be below the bilge pump, hence the bilge pump would be pumping nothing but air.
When purchasing and wiring up bilge pumps ensure that the voltage of the bilge pumps match the boat supply voltage, most bilge pumps are 12V, but there are some 24V bilge pumps available.

[@norcal8718]

I am a mechanic by trade and you are correct, this is a very simple circuit which I've done many times. With that said, I know you are trying to make it as clear as possible for the viewers but you're really not explaining it well enough to make it understandable for beginners, you need to do one wire at a time instead of just saying "hook it here hook it there" because some people aren't going to understand it or get it. You made an awesome diagram on that board so maybe slow down and one wire at a time pointing to your visual. I would like to thank you for sharing your time and knowledge with everybody, you are very much appreciated 👍🏻.

[@Kaiwaka27]

Bloody awesome tutorial on bilge pump wiring. Thankyou thankyou so simple and un complicated.

[@seldom_seen8713]

Just what I was looking. Explained extremely well....Thank you Sir.

[@the1joncinnj]

Great video. Clear and concise. Thanks for adding.

[@BoatFittings]

Hi many thanks for your kind comment. Kind regards, Richard

[@TheNyfishguy]

Thank You for a simple Informative & to the point tutorial👍🏼👍🏼👍🏼

[@BoatFittings]

Glad it was helpful!

[@peterkaldanis9769]

Great video, thanks for uploading!

[@BoatFittings]

Glad you enjoyed it!

[@bobgil3464]

Finally someone explained the installation of a float switch in easy terms. My boat manufacturer said they don't add the float switch to save the consumer money. I would rather pay a few dollars more for the switch than find my boat sunk at the boat dock.

[@BoatFittings]

Hi thanks for your comments, and absolutely worth spending a few dollars more!

[@heddas68]

Finally is right!!! We were having a misunderstanding about the two wires on the switch both being positive. Makes sense now! Thanks!

[@the1joncinnj]

Great video. Clear and concise . Thanks for sharing.

[@bobbeckstead8340]

Do NOT trust a float switch to keep your boat from sinking. You have to keep an eye on a wet-slipped boat.

[@noblece]

excellent video!

[@BoatFittings]

Thank you very much!

[@Michael-zd9xs]

Nice job

[@BoatFittings]

Thank you! Cheers!

[@mauivi1113]

I changed also the switchplan as you showed and also i put in the circuit a buzzer. Like that i recognize also when the automatic works.

[@BoatFittings]

Hi thanks for your comment - that's an interesting idea, thanks for sharing your idea. All the best, Richard

[@MJMCHRONICLES]

Thank you

[@BoatFittings]

Hi thanks for your comment. Kind regards, Richard

[@Xray.71]

Awesome!!

[@BoatFittings]

Thanks for your comment.

[@hectorrodriguez-ye9lm]

Great inf

[@SandmannOZ]

A couple of thoughts... it's still a good idea to have a manual switch that can disable the float switch... in case it gerts stuck on (if some detritus gets stuck under the float switch etc), and so it can't turn on while you're refueling, connecting gas cylinders, etc as the float switch's contacts and the pump's brushes will make a very small spark internally and of course the pump's located at the lowest point where fuel/gas vapours will collect. Also, if you fit a small light to the common wire that connects both the manual & float switches to the pump you can have a "pump running indicator" which will alert you to when it automatically turns on. If your boat's filling up more often than it should be due to a leak or something it's not a bad idea to have some sort of indication that the pump's running, and if you turn it on manually and it doesn't light up it alerts you that the fuse is blown or that there's some other problem. You can easily mount the light next to the manual switch. (I also put an "automatic active light" next to my disable switch to remind me that the float switch is activated. I also fused both the automatic and manual circuits individually so if one fuse blew I still had the other option.)

[@BoatFittings]

Hi thank for your comments. I think you have made some very good points there, and I like your thinking. Much appreciated. Richard

[@bobbeckstead8340]

Like a three-way manual. You can also house the float so debris can't get stuck under it. But, I've seen floats stick open from grunge build-up at the hinge or even from just their own friction.

[@shynepo050]

Nice

[@BoatFittings]

Thanks for your comment. All the best, Richard

[@matthewswartz8155]

Thanks for diagram

[@BoatFittings]

Hi thanks for your message, glad you found it useful.

[@choimdachoim9491]

The manual switch should be one that lights up when it's "on" and the pump should energize a tell-tale light at the helm when it's operating. Manual switches can be accidentally turned on which is something the operator needs to know about. If the bilge pump stays on for a long time via it's float the operator needs to know that something is either stuck or there's a big leak somewhere.

[@timparker7275]

Can you zoom in on the connectors ( closeup) ie eg.the pos from switch and pigtail to 3way switch ,hard to see... I had to wire 2 negatives into 1female connector...after the instructiions said" Connect the neg wire from pump to neg terminal on float switch. Now Connect neg terminal of battery to neg terminal of switch... Helpful if more closeup of actual connectors thx great video... And of course instructions are not always diagrammed properly

[@noes.castillol.4935]

🙏🙏🙏🙏🙏👌👌👌👌👌👌Great Video👌👌👌👌👌👌🙏🙏🙏🙏🙏

[@BoatFittings]

Thanks 🤗

[@davecozzi6937]

Great video I had the same worries about float switch failure so this helps a lot! You referenced another video that will include a switch panel, is that still in the works? Also, what size fuse should we use if the pump says 4amp but the switch says 20 amp. Tsunami T800 bilge pump with Rule 40A float switch for reference. Thanks again!

[@BoatFittings]

Hi thanks for your comment and questions. The fuse should be selected based on the pump as it has a lower rating and you are therefore wanting to protect the pump from over-load. Yes the switch panel video is due pretty soon - hoping to get part 1 out in the next 10 days. All the best, Richard

[@bobbeckstead8340]

The amp rating for the switch or the float is the current flow it can handle without burning up - it's essentially irrelevant to the appliance circuit. What you want is the proper amp rating for the appliance circuit. If your pump can draw max 8 amps, use a 10 amp protector; if it can only draw 4 amps use a 5 amp protector. You're never come close to burning up a switch.

[@josephpergola1099]

how will I connect the 3 way splice waterproof for saltwater use?

[@joncr1]

Great easy to understand vlog, Thanks. What are your thoughts on integrated float switches in the bilge pump? Or go for both for the £25 quid for an extra bilge to guard against single bilge failure in parallel with the existing separate float switch and bilge pump here? Overkill and a more things to fail of worth it as it's not much more money for peace of mind.

[@BoatFittings]

Hi Jon, many thanks for your comment. I am glad you asked this question, I am in favour of many bilge pumps for added redundancy and safety, I would suggest at least 2 and sometimes 3 or 4 or more are appropriate for larger boats. I am quite a fan of pumps with an integral float switch as well. Richard

[@a1aadvancedmarine88]

I wouldn't own a boat with only one bilge and I always push my customers to add a second one ESPECIALLY if the vessel lives in the water. I also go a little overkill on the GPH cheap insurance if you have a thru-hull fitting or similar type failure.

[@bobbeckstead8340]

Separate float and pump only. Why? Because it's cheaper and easier to replace the bad one alone. If your float fails ($30); if your integrated detector goes bad, you have to replace the whole works ($200+).

[@bobbeckstead8340]

It would make sense to explain what a "larger" boat is. Up to 23 ft or so, one pump can more than suffice depending on its boat design and conditions of use. Twenty-three to 30, probably better to have two pumps. Thirty ft or so and up, go three. And, so on. @@BoatFittings

[@bobbeckstead8340]

If a thru-hull goes, you had better have a whole lot of GPH (that you're not going to get from even two or three typical pleasure boat pumps) and plenty of battery power (also unlikely). Keep an eye on your boat.@@a1aadvancedmarine88

[@jeffdege4786]

Do float switches never stick closed? That is, do they never fail in such a way that the pump is stuck on? A three-position switch might be a good idea, toggle on/off/auto. And I'd want a counter or hour meter, so if I was away from the boat I could know if the pump has been running.

[@bobbeckstead8340]

They can stick in either the on or off position - and, often do.

[@jmca3324]

It'd be interesting if you could show how to waterproof a 3 wire splice ,as is required for auto override. Pumps and float switches are never supplied with enough cable to reach somewhere dry in commercial fishing boats fish hold settings where there is always water dripping through the floor from melting ice , in such settings automatic pumps are ideal but manual override is also required for all the reasons you outline . Thank you.

[@BoatFittings]

Hi many thanks for your comment and explaining your situation on commercial fishing boats. I will put some thought into watering a 3-wire splice.

[@petermorton2869]

Regan my son got a special electrical clip over the main bilge pump wire which the female spade clip is crimped to the wire on the float switch which you push straight onto the male clip & the female clip has heat shrink on it & I completely wrapped over with black electrical tape & I hunted high & low for that type clip & was lucky to get one like that & it saved me cutting the wires & if I couldn't get this clip I would have got a complete T water proof connector from AliExpress Store & the clip I got is a T one as well but wasnt water proof but wrapped with electrical tape should work well & wrapped over electrical conduit & hopefully that's helped & it's pretty dry underneath where wires are Kind Regards Peter

[@bobbeckstead8340]

I would advise against a three wire splice. Use a terminal block that you can render water resistant or a quality, waterproof plug.

[@bobbeckstead8340]

Always go with a plug that's engineered to be water tight as opposed to heat-shrinks and (or) tape - neither is ever water-tight.@@petermorton2869

[@irishgold8783]

This

[@williamcollects393]

Hello, I've subscribed, I just brought the seaflo 4700 GPH and have no idea what cable I need all I k ow is its 14 gauge but from watching other you tube videos there saying copper is a no go with these pumps... This is to empty a swimming pool and will be connected straight to a battery could you help me in anyway or give me some guidance because I'm genuinely out my depth any help would be massively appreciated

[@BoatFittings]

Hi thanks for your comment and question. With regard to the wire I am not saying copper is a no-go, but there is an advantage in the long term for pre-tinned copper as it will not corrode. If you cannot get pre-tinned then normal copper wire would be ok. The most important thing when choosing the wire is that the gauge is thick enough. Thicker is not a problem, but thinner can lead to over-heating. I hope that helps a little.

[@michaelricatto9346]

Would there be any problems if both switches went on at the same time?

[@BoatFittings]

Hi thanks for your question. There would be no problem at all if both switches went on at the same time.

[@finno123456]

Hi what gauge wire can you with the pump and float switch it draws 15amp. And what amp fuse can i use Thanks

[@BoatFittings]

Hi thanks for your question. Normally the pump should have a label showing the recommended fuse rating. If it actually draws 15amps then the fuse needs to be a bit higher -eg 20Amps. As for wire gauge a quick google on 'wire gauge vs Amps' should bring up some good results. All the best, Richard

[@bobbeckstead8340]

Correct about wire gauge and appliance amp draw, but remember that TOTAL CIRCUIT LENGTH is important as well. A pump that is 4 ft from the battery (8 ft circuit) can get by with a smaller gauge wirenthan the same pump that's 24 ft from the battery. @@BoatFittings

[@JP-rf7px]

For safety, mount a second switch a little higher than the first in parallel with the first so if the first doesn't activate, the second one will a little later. Or hook the second switch to a second pump and add a buzzer wired across the second pump's leads to warn you when it comes on. Cheap insurance for an expensive boat.

[@bobbeckstead8340]

Good advice. Floats are notorious weak links - they fail frequently.

[@Enrx90]

Good video brother… asking about fuse size its confuse me Little bit .. I know that the fuse should be less than Amp max current … they mentioned in the manual it should be higher ?? Can you explain it please ? Thank you very much

[@BoatFittings]

Hi Mohammad, thanks for your question - I will try to answer it with an example. First thing to say is that fuse is to protect when things go wrong. So normally the fuse will not blow. Now for example we could have a bilge pump that normally takes up to 7 Amps. So in the normal situation the pump takes 7 Amps at most (when starting up, or when working hard) or when working less hard around 4 Amps. So the fuse should be rated above 7 Amps otherwise it will blow every time you turn the pump on so we could have an 8Amp or 10Amp fuse. So what could happen when something goes wrong ? The pump could get jammed or seized up and cannot turn. Then when you turn the pump on it takes more current than usual - maybe 12Amps or 15Amps and in this situation it would get hot and maybe burn out or melt the wires (bad!). Here is where the fuse comes in and as soon as the pump takes more current than the fuse rating, the fuse blows to keep everything safe. I hope that answers you question? All the best, Richard

[@Enrx90]

@@BoatFittings so Appreciate for the answer no it’s makes sense for me to continue my project thank you so much for your help brother.

[@billh6988]

Have an existing on/of switch and pump. Pump has brown and black. Float has brown and a brown/white wire. I ran fuse to battery + to brown/white on float. Other float brown wire to brown on switch. No power. Any ideas?

[@BoatFittings]

Hi Bill, thanks for your comment / question. I can't make comment based on your wording as I might mis-interepret what you have done. If you send me a photograph though to [e-mail] I could try and make a suggestion. All the best, Richard

[@billr6865]

Could you add a alarm system. So if the boat is collecting water and the pump is on for say 2 min a alarm will sound

[@BoatFittings]

Hi Bill, that is a great suggestion. I will have to think about that one. I will definitely put it on the list. All the best, Richard

[@peterhamilton8778]

Quick question. On my boat the bilge pump works when manually switched on but not from the float switch. However, when the system is plugged into the wiring harness for the other bilge it works. in other words, the float switch works fine, but not when connected to one of the harnesses. Very confusing.

[@bobbeckstead8340]

The float is not getting power from one of your harnesses due to a bad contact or tripped breaker (or burned fuse).

[@petermorton2869]

Hi Sir how I'm going to wire up my float switch is by putting one from the float switch to the positive wire to the bilge pump & the other wire on a waterproof fuse holder & goes directly to the positive side of the battery as the other positive wire on the bilge pump already goes to the switch on the dashboard panel & it never had a Float switch put in the 2015 6.20 metre cabin fiberglass boat only the 1100 gph bilge pump was installed & it should have had a float switch installed in the first place as the boat I brought new had a bad Design Fault the bilge pump outlet was at the back of the boat which should have had the bilge pump outlet up at the side of the boat as when I get more people in the boat I noticed that I couldn't get the boat on the plane & when I got back to the boat ramp & got the boat onto the trailer & drove up the boat ramp & park at the vehicle & trailer up the hill well away from the boat ramp I took the 3 bungs out the middle bottom bung that I took out there was so much water coming out it wasn't funny & took a long time to drain out & even my youngest daughter said to me that's a lot of water coming out of the boat & shouldn't be that much amount of water coming out from a near new boat & it had me stumped why there was so much water coming out & it wasn't until later down the track that I found that the water was coming in from the bilge pump outlet & the it also had damaged the toilet pump NZ $300.00 later as the toilet wouldn't work & I had to clean out the toilet as it wouldn't flush & when I got the toilet pump out it was all rusted up as the bloody water that was coming in from the bilge outlet had gone right up the the bow of the boat & got into the toilet pump & now I've got a float switch that's going to stop the water going right up to the bow & later down the track I'm going to have the bilge pump outlet up high & at the side of the boat & have it professionally done & have the old bilge pump outlet hole professionally blocked off pissed me right off well having that done right & I will never never have that problem again & the only way I knew the water was coming in from the bilge pump outlet was I got the garden hose & I didn't have the tap on full running & just trickling in & I had the centre bung out & you should have seen the water coming out the was a lot of water coming out of the bung hole & so having the float switch installed the water that comes in through the bilge pump outlet will gradually pump the water out again Kind Regards Peter PS very good of you Sir for showing how wire up a float switch & on my dashboard panel there no way I can install an automatic switch but will automatically switch it's self on & I'm still be able to switch it on manually as well but most of the time when I turn on the main switches the float switch will be fully Automatic when I'm out in the boat & I get some spare money I will then change the bilge pump outlet over up to the left hand side of the boat & have the old bilge pump outlet hole completely professionally blocked off which will completely solve that problem I can't understand why the boat manufacturer didn't have the bilge pump outlet going up to the left hand side of these boats & there are a lot of other boat Manufacturers have their bilge pump outlets up at the sides of the boats so no water can go in through the bilge pump outlets

[@BoatFittings]

Hi thanks for your kind comment, and your entertaining story. All the best, Richard

[@petermorton2869]

@@BoatFittings Hi Richard Peter here again I apparently had put the new bulge pump outlet higher but apparently not quite high enough & I went out in the boat on last Sunday New Zealand time & when you get the boat on the plane the new bulge pump outlet goes under the water & let's water into the hull & operates the float switch which switches on the bulge pump & you slow down in the boat the bulge pump outlet is out of the water an a mistake on my part & will have to take the outlet fitting off & have that hole blocked off by the Fiberglass repair guy Rod to block that hole off & I rang Rod yesterday & he is going to quote me $200 to $300 to block the hole off bugger more expensive & the first bulge pump hole outlet to have blocked off was &189.00 & now it's more money Bugger & the other new bulge pump hole outlet has to go up another 5 to 6 inches what a bugger & it will be completely out of the water so no water can get into it a BLOODY BIG MISTAKE ON MY PART & then it will be all sorted & it a stupid place in the first place for the boat builder to put the bulge pump outlet at the back of the Smuggler Sport 6.20 boat in first place where water could get into it all the time & it was only the bulge pump was installed & that finally destroyed our toilet pump & that was $300.00 later & now it costs me $200 to $300 to have the blocked off bugger & that money could have gone towards fuel for the boat as petrol is not cheap anymore it is 2.75.9 cents a litre for 91octane fuel & other parts in Auckland New Zealand you could be paying $2.86.9 a liter for 91octane fuel & I have a 200 liter tank in the boat & it is nearly down to half a tank of fuel which is not cheap to fill the tank & I understand the fuel prices are going to up around Christmas & our cost of living is already high in New Zealand & will even go up more some parts in Auckland New Zealand Diesel is already at $3.00 at a liter Bloody really expensive & that's why our food prices are so high & everything is else is going up as well & you have a Lovely Nice Day or a Lovely Nice Good Night Richard Kind Regards Peter

[@JacobBarnesDjbbkk]

if i’m just going to use the manual switch without the float switch… would i still need a fuse? sorry i know nothing about any of this haha

[@edgar-valentine]

I would always fit a fuse, as a precaution,

[@user-cy6xr8nk7u]

The float switche will burn out pretty quickly if it's carrying too many amps. Best practice is to use a relay for larger pumps.

[@bobbeckstead8340]

The wiring illustrated on the blackboard will NOT work. The float switch will not work because the circuit is open at the manual switch. The manual switch will not work unless the float switch is closed. The white board is correct and will work perfectly. The manual switch circuit has to by-pass the float and go direct to the bilge pump and the charge to the float must by-pass the manual. This can also be achieved with a three-way switch (manual-off-auto). I put the manual breaker (fuse) in the line immediately AFTER the switch and the breaker (fuse) for the float close to the battery (before the float). The common positive to the pump contacts the manual and float feed at a terminal block or a three-prong watertight plug (never butt connect them).