Bilge Pump Wiring Question

Stu Jackson · May 4, 2015

https://www.bluesea.com/support/reference

Scroll down to the fuse-wire size chart and download the PDF. Only YOU know the distances involved. + AND -

JK_Boston_Catalina310 · May 4, 2015

Have you pulled the pump to see if there is something blocking the impeller? A 10 second run kind of sounds like something is blocking the impeller and then the breaker pops.

If you follow the link that Stu posted you will see that your wire size puts you in the 10% voltage drop category. I wouldn't do that on my boat.

And just checking but you do not have a check valve in line, correct?

Don S/V ILLusion · May 4, 2015

In addition to the above, bad connections which can build resistance could also contribute to the problem. When did u last check all connections?

Stu Jackson · May 4, 2015

Piratenorm said:
Stu, if I'm reading this chart right, and I blew up the scale to make sure I was, I need 14 gauge wire (which I can understand) AND a 30 amp fuse? Wow. For 3.4 amp draw pump? Sounds excessive. This I read is what I need for the single wire which would be for the Auto function of the pump. But that chart doesn't include the size of the breaker at the panel I should be using for the manual activation. Again, a 30? If so, why in the world was a 5 amp breaker in the panel in the Bilge Pump position in the first place (how I bought the boat...)
Just want to be sure. Again, Thanks.

The 5 a protects the motor, the 30A protects the wire and this fuse should be close to the battery. You can get a very inexpensive 30A glass fuse (just like on the chart) to fit in a fuseholder that costs less than $5.

Maine Sail has been repeating this for years on this and other boards. It's great that you're interested in doing it right. Please, buy a book on electrical boat systems, 'cuz that saves me having to type book-loads of "why?" answers.

Short answer: if the circuit goes wonky for any reason, like if your bilge pump melts but keeps drawing, even if the 5A fuse blows, the wire could heat up and melt and the 30A saves your boat and your a$$ because there's tons of energy stored in batteries. That's the Cliff Notes version.

JK_Boston_Catalina310 · May 4, 2015

Piratenorm said:
Again, a 30? If so, why in the world was a 5 amp breaker in the panel in the Bilge Pump position in the first place (how I bought the boat...)

I haven't looked at the wiring side of a MKI C-30 in a while but I think there were other problems with this panel wiring for the bilge. For instance is this actually a bilge pump switch meaning does if have a "Auto" and "Manual" setting with off being in the middle?

Most people want their bilge pumps wired "directly" to the batteries. [I put directly in quotes because there are ways to accomplish this without actually connecting to the battery but to a battery post on a 1/2/both/off switch.] This is done because typically you want the bilge pump to be always. If you are connected through the panel you might be shutting off your bilge pump when you shut off your batteries by the 1/2/both/off switch.

If you are connected just to an on/off breaker on your panel I would suggest you change that setup. I would consider adding a panel like this.

I would wire it direct to the battery with the correct size wire and fuse. It would let you know how much your pump is running and sound an alarm if it was excessively running. Add a high water alarm and you're in business.

Also, I personally try to stay away from the Rule bilge pumps. Especially the ones with the internal floats. I just haven't had good luck with them.

Good luck and fair winds,

Jesse

danstanford · Sep 21, 2015

Stu and others, I need to replace my pump and switch which is no problem but I am wondering about the wiring. Should I try and trace the wires back to source and replace them entirely or can I cut and splice just prior to the pump/switch? IF I can splice in, how do I do about waterproofing the splices?

Thanks,

Dan

The Garbone · Sep 21, 2015

Depends on your setup.

On mine I ran all new wire from the start battery with a fused link. I still had to splice the switch and pump to the wire, used good quality crimps that are heat shrink with adhesive and a good crimp tool.

Titan 11477 Ratcheting Wire Terminal Crimper https://www.amazon.com/dp/B0069TRKJ0/ref=cm_sw_r_awd_aWcawb75XWS7P

3M Heat Shrink Butt Connector Kit 140 Piece https://www.amazon.com/dp/B008HMHJDO/ref=cm_sw_r_awd_VWcawb30DG60Z

Anonymous 121765 · Sep 22, 2015

Personally,

I have never had much luck with internal float switch pumps. I have a 1980 C30 MKII & use a rule 5000 pump & separate float switch. But, I ran & supported the wire connections & attached them to the underside of the bilge on the cabin sole next to the bilge wood cover using recessed screw heads & installed a fusible terminal block for both the pump & float switch. And, these were NOT under bilge water as I have frequently seen.

This was a breeze, I located this block inside the engine compartment just aft of the forward wall & as high to port as I could get. It is high & dry. I also have a 3 position bilge switch on my panel & this is fused also.

Listen to Stu & make sure your wire gage is suitable especially for the length of run as resistance will build up. Never be afraid to go heavier gauge as, this will cut down on resistance/heat. I tell folks that it doesn't take much to screw up 12 volt systems. Proper gauge for length is paramount. Read what Mainsail says, he's been doing this for years.

Off the pump & float switch, I use soldered push pin connectors, for when you need to do changeouts, you don't have to re-wire the whole extra length. I also use a connector coating for the solder & a protective heavy grease over the connections. No oxygen, no corrosion problems.

What most people perceive wrongly is this. People think that having a smaller boat & bilge, they only need a smaller pump. But, it is just the OPPOSITE. Having a smaller bilge & pump, your boat will fill up faster with flooding water than if you used a pump size that can remove more GPH. You may discover that you do not have the luxury of GP hours before floundering so, size is important. Just ask any woman.

CR

Cayennita · Sep 25, 2015

[I have owned quite a few boats in the last 46 years. Only on new one. On all the boats I have replaced EVERYTHING related to bilge pump. Pump, wires, breakers, etc. iI I never trust TPO on this critical systems. Not worth saving a few dollars.

wufibugs · Sep 25, 2015

Don't mean to hijack this thread. I want to add a bilge pump warning light to my cockpit panel so I am alerted to when the pump is running. I assume this should come off the wire between the pump and float switch.

Anonymous 121765 · Sep 25, 2015

Wu,

I understand you want to know if your bilge pump is running. I also assume you only have a panel circuit breaker/fuse for your pump. I, would install & wire in a 3 position pump switch @ your panel & let this control your pump/float switch. You set it on manual, auto or off. Just be sure you are not over thinking it pal.

If wanting to be alerted when you pump is running, they also have in-wire alarms you can wire off (when you install it) your 3-POS. switch & mount this speaker somewhere behind your panel. This WILL alert you.

This way, you won't have to fish wire & mount an indicator light in your cockpit panel. What if you are NOT in your cockpit to see the light. An alarm sound to me, is a much more viable approach no matter where you are located on deck.

I don't know why you feel this is a priority unless you may have bilge water building up when in your boat. If this is the case, maybe it's not the indicator light you need to address but, to find out where the water is getting in from.

Your cooler and/or your shower may be draining into the bilge but, there are other ways to isolate and/or fix these issues.

CR

wufibugs · Sep 25, 2015

Actually, Ron, I don't have an issue with water in the bilge, or at least I won't when I replace the shaft seal that leaks intermittently. I just don't want to be the last to know there is water in the bilge while I'm cavorting above decks. While an alarm is certainly an attention getter, it issues a command to stop and take a look. A light that comes on for a few seconds lets me be aware without panicking all on board.

Anonymous 121765 · Sep 25, 2015

Wu,

A bilge pump running for a few minutes should not be alarming.
If it keeps running, yea maybe.

What's better, your position, line of sight or........your hearing?
Remember, you can always have both, indicator & alarm.

I like to keep things simple that way, I am less disappointed.

Remember, different strokes for different folks. What works best for me may not work best for you of someone else. So at the end of the day....who's right or who's wrong?
Maybe all, maybe you, maybe me maybe no one. It's all personal choice pal.

Just have fun sailing or what I like to call, "Flying sideways."

CR

Maine Sail · Sep 25, 2015

Piratenorm said:
On my Catalina 30 I use the Rule fully automatic 1100gph BP, the white oval one over the blue strainer, but I rarely get a season out of it without problems. Now the automatic feature doesn't work and when I flip on the switch at the panel manuallyl I get 10 seconds before the breaker trips, then 30 seconds later it makes a slight click and I can run it for another 10 seconds, and so on.
I searched the system and found a 5 amp breaker on my Blue Sea panel that I would have thought would be fine as the packaging for a new pump says the draw is only 3.4 amps, but maybe that is too low a breaker? The pump comes new with 18 gauge wiring and for the 8 foot run to the breaker I use 16 gauge, again I'd think that would be right but if I knew for sure I wouldn't be posting this question.
The auto bilge pump feature has a 6 amp fuse but that blows easily.
What a) Breaker should I have, b) gauge wiring from the panel to the pump and c) size of fuse for the auto side.
As always, Thanks.

#1 Stick with Rule non-automatic pumps and a bilge switch such as the Ultra Safety Systems Mini or Junior... The Rule automatic pumps are horribly unreliable. Heck, for that matter, all centrifugal bilge pumps are pretty damn unreliable...

#2 Your bilge pump should be sized for 3% or less voltage drop. The performance of these pumps is directly impacted by voltage at the pump and head.

#3 Often the best and most simple choices for a bilge switch is the AUTO-ON-OFF bilge switch with built in fuse holder. Blue Sea, Rule & others make them..

#4 NEVER place a fuse larger than what the bilge pump maker recommends, for your particular pump, in the bilge circuit. The fuse at the battery can be sized for the wire to the bilge switch but the bilge pump fuse must be sized at the pump manufacturers suggested size and NO LARGER.

Why...?

A while ago I had a new Rule 500 kicking around my shop so I attached it to a battery... Rule recommends a 2.5A fuse for this pump.

Battery = Group 31 AGM Resting Voltage 12.77V

Meter = Fluke 376 w/Inrush & min/max NIST Calibrated & Fluke infrared

These are the tests I ran:

12.75V - Ran pump dry for 10 minutes and saw 1F rise (Fluke infrared thermometer)

12.72V - No Load (spinning in air) = 0.7A with no load (in-rush/startup current current = 2.7A)

12.72V - Locked Rotor with a 3A Fuse = Blew Instantly

12.71V - Locked Rotor with 5A Fuse = Blew nearly instantly (about 6 seconds)

12.71V - Locked Rotor with a 15A Fuse = No blow 10.9A continuous draw, pump getting rather hot to the touch after 90 seconds of stalled rotor. Discontinued at 2 minutes and 10.7A (heat build in windings up likely caused current to drop a bit) bilge pump was at 136F at 2 minutes of stalled rotor..

12.70V - Locked rotor measuring inrush with 5A ATC fuse - Inrush = 10.9A - Fuse blew (separated/burned) but failed unsafely leaving a bit of metal across tabs. This is my first live example of where the AIC (amperage interrupt current) matters when directly connected to a battery!!!! Scary stuff! I ran the load for approx four additional minutes and the "failed unsafely" ATC 5A fuse still failed to blow even at 10.7-10.8A pump was very warm when I discontinued forgot to measure but hot potato hot.......

Bottom line, you want a fuse that will blow with your pump in locked rotor mode otherwise it can continue to heat and then melt and then potentially start a fire......!!!!!!!!!!!!!!!!:cussing: Sadly I see incorrect fuse sizing in bilge pumps almost every day. The boat I was working on an hour ago had a bilge pump catch fire two years ago when ice stalled the rotor.. Fortunately the pump failed internally, & fused itself, before it started the boat on fire.

Bottom line do not use a fuse larger than what the pump maker suggests. If the pump is not working properly, you buy a new one...