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Old 20-01-2022, 21:12   #1
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Potting epoxy for bilge pump connections

Has anyone tried electronics potting epoxy for waterproofing electrical splices? A good waterproof bilge pump connection uses junction boxes placed high up but I'm not happy about the fact that the taps or leads that come with bilge pumps, although pretty long (so the splices above bilge waterlevel) but are much too thin (and unjacketed) Too thin leads are a problem for many items a aboard including Raymarine autopilot) I guess you can make up for the thin span of wire by using thicker connecting wire (which creates other problems)...If you cut off the wires to attach thicker wires closer to the pump you risk water intrusion into the splice, but the only truly waterproof way can think of is by using potting epoxy to splice the connections, covered with heatshrink for strain relief?
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Old 20-01-2022, 23:08   #2
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Re: Potting epoxy for bilge pump connections

solder the conductors together then slip heat shrink over the splice and shoot a good shot of hot melt glue into the heat shrink. The heat shrink will shrink and force the hot melt into any voids sealing the splice.
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Old 20-01-2022, 23:27   #3
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Re: Potting epoxy for bilge pump connections

Quote:
Originally Posted by Cyrus Safdari View Post
Has anyone tried electronics potting epoxy for waterproofing electrical splices? A good waterproof bilge pump connection uses junction boxes placed high up but I'm not happy about the fact that the taps or leads that come with bilge pumps, although pretty long (so the splices above bilge waterlevel) but are much too thin (and unjacketed) Too thin leads are a problem for many items a aboard including Raymarine autopilot) I guess you can make up for the thin span of wire by using thicker connecting wire (which creates other problems)...If you cut off the wires to attach thicker wires closer to the pump you risk water intrusion into the splice, but the only truly waterproof way can think of is by using potting epoxy to splice the connections, covered with heatshrink for strain relief?
My experience has been pump failure over electrical failure, necessitating pump replacement, which is easy to do with a good junction block mounted high using quality connectors and heat shrink. Heavier cable to the block eliminates any voltage drop.
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Old 20-01-2022, 23:50   #4
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Re: Potting epoxy for bilge pump connections

If you use solder seal connectors, you have the solder included in the connector. You put the ends together and within the ring of solder. Heat the center (solder) first. When the solder has flowed into the wire, move the heat to the ends to shrink the tubing.
You have a watertight seal. A heat gun or propane torch works well.You can buy the connectors on ebay or Amazon.
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Old 21-01-2022, 01:42   #5
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Re: Potting epoxy for bilge pump connections

I cut the top off of a water bottle and put it upside down over the terminal block, and screwed it to the terminal block support. Water splashing from the top is deflected, and if the water ever gets as high as the bottle it can't get into the bottle.
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Old 21-01-2022, 06:56   #6
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Re: Potting epoxy for bilge pump connections

I seem to remember that Practical Sailor tested the "solder seal" type connectors and wasn’t impressed. That conforms to my experience with them over the years. Even the ones made by a reputable manufacturer (not no-name Amazon/EBay) tend to be difficult to get consistent results, even in controlled manufacturing. Wires have to be new and clean. Temperature has to be high enough to heat the wires so that the solder actually sticks to the wire; just melting the solder isn’t good enough. To get the joint hot enough for the solder to work properly while not getting the sleeve and heat shrink "too hot," you’ll need a carefully controlled heat source; a propane torch won’t give consistent results.

In my experience, these have been much less reliable than a properly made and sealed crimp connection.
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Old 21-01-2022, 06:59   #7
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Re: Potting epoxy for bilge pump connections

For bilge pumps, I typically use adhesive lined heat shrink crimp connectors. And make sure the pumps are wired with tinned wiring, that way if a leak does occur in a connection it's not instant death for the wires. I also try to keep the crimps as high up as possible to minimize the chance that they'll ever get wet.
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Old 21-01-2022, 07:03   #8
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Re: Potting epoxy for bilge pump connections

I like the solder seals in theory. Junction boxes are the textbook solution for bilge pumps. I am not happy about using thicker wire to make for thinner leads, because it creates heat and reduces pump efficiency. A bottle neck in a critical circuit that should be oversized if anything. Why on earth would anyone think a 2000 gph bilge pump have the same sized leads as a 500 gph pump.

The advantage of using the potting epoxy over hot glue to help seal an electrical splice is that the epoxy is supposedly heat resistant, designed specifically for this purpose. Hot glue remains a little flexible too.
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Old 21-01-2022, 07:10   #9
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Re: Potting epoxy for bilge pump connections

Conceptually I agree the lead wires on the pumps are too thin, electrically itís OK in terms of voltage drop at least.
If you want a jacket itís easy to slip some PVC tubing or Teflon tubing over the wires.
I think the adhesive lined heat shrink crimp connectors are the best way to make the connection. You could enclosed those connections in a junction box for additional protection but I donít think itís necessary.
I worry that epoxy would heat cycle and open up voids that could let moisture in.
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Old 21-01-2022, 07:11   #10
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Re: Potting epoxy for bilge pump connections

You have to use any tech correctly. You have to use the right heating too for the right job, not just a Bic lighter, etc. Indeed I suspect he reason why the ABYC suggests the connectorsit does is simply because it is a compromise for inattentive worker rather than he quality of the tech itself. There are better ways of making waterproof splices, they just take more time, effort and care - three things rarer than butt splices
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Old 21-01-2022, 07:22   #11
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Re: Potting epoxy for bilge pump connections

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Originally Posted by Cyrus Safdari View Post
... Indeed I suspect he reason why the ABYC suggests the connectorsit does is simply because it is a compromise for inattentive worker rather than he quality of the tech itself....

You would be incorrect about this. The reasons given in the development documents, based on experience, were:


  • Solder will soften if the wire over heats, and a solder-only join can pull apart.
  • Flex fatigue and wire breakage is more severe with solder only joins. I have seen this in testing and the field.
  • Corrosion is more severe on soldered joins. I've seen many soldered wires corrode off at one end, more than crimps. Properly located and sealed, neither fails.
Workmanship was not mentioned. Personally, I find soldering no more complicated than proper crimping (the crimper must be properly adjusted and the correct dies must be used).
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Old 21-01-2022, 08:08   #12
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Re: Potting epoxy for bilge pump connections

The leads that come with the bilge pump should be long enough to easily get out to the "danger zone" in the bilge. I don't know why MFG's put such thin wire on them, but I would not cut back so that you have a connection that could potentially be in the water. My approach is to size the wire for 3% voltage drop which tends to result in a slightly over sized wire awg. Pump won't know the difference. Just use quality heat shrink butt connectors and zip tie the connection as high in the bilge as possible. Don't over complicate it. Pumps die so you'll be remaking the connections anyway so no point in making things more difficult for you later down the road.
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Old 21-01-2022, 09:08   #13
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Re: Potting epoxy for bilge pump connections

"Quality heat shrink butt connectors." Yes, good quality is important. But one of the ugly details here is that, even if the #14 or #16 wire built into the pump is "big enough," the wire that you use to connect to the power source is very likely going to be bigger since it is a longer run. Trying to use a standard butt connector to join #14-16 on one side to #10-12 on the other is going to result in some poor compromises. So one is left with buying Step-down butt connectors (which are available but not commonly stocked by most sellers in small quantities) or using some kind of terminal block or plug/socket, which has its own problems.
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Old 21-01-2022, 09:37   #14
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Re: Potting epoxy for bilge pump connections

http://www.cruisersforum.com/forums/...d.php?t=208821

http://www.cruisersforum.com/forums/...d.php?t=193531

From Rod / Maine Sail:

https://marinehowto.com/marine-wire-termination

https://secure2.pbase.com/mainecruis...ng_small_wires
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Old 21-01-2022, 09:38   #15
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Re: Potting epoxy for bilge pump connections

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solder the conductors together then slip heat shrink over the splice and shoot a good shot of hot melt glue into the heat shrink. The heat shrink will shrink and force the hot melt into any voids sealing the splice.
Or just use double walled adhesive lined heat shrink
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