Simple wire splicing question

This is a very basic question and I feel kind of silly asking but...

I have a dry bilge pump I want to install. It is simply a low capacity, and low profile pump designed to get out the last bit of water from the bottom of the bilge that the regular bilge pump doesn’t get.

I don’t want to create another thru-hull so I am going to run the outflow from this into the shower sump where the shower sump pump will pump it overboard. I also would like to put in on the same electrical circuit.

I want to splice the + and - of this new bilge pump into + and - wire for the shower sump pump. So my question is this...

What is a good way to splice the wires in the bilge area? They shouldn’t be wet, but they should be able to get wet if you follow me.

I'd spend $15 and install a little IP67 rated junction box, then just crimp connections and shrink wrap as normal. IP67 is rated to withstand immersion for 30 minutes.

I use terminal blocks and jumpers to connect two or more wires to one wire.
https://www.bluesea.com/products/category/19/Terminal_Blocks

HopCar said:

I use terminal blocks and jumpers to connect two or more wires to one wire.
https://www.bluesea.com/products/category/19/Terminal_Blocks

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Me too.

Me three. Short little terminal block, a few Anchor brand or similar heat-shrink ring terminals, bam...easy, quick, reliable. Of course, using tinned marine wire should go without saying....

Waterproof (adhesive heat sealed) butt splices are designed for this. Millions of artesian wells depend on heat sealed butt-splices and most are fully submerged for the entire life of the well pump.

#1 Use the correct crimp tool for the job

#2 Use a quality heat sealed butt-splice eg: Molex, AMP, FTZ etc..

#3 Properly heat seal the terminal using a heat gun, not flame. Heat it until any bubbles are gone and the adhesive begins to "flow". Heat from the center outwards...

#4 When properly melted the "glue" will create a small ring at each end of the terminal indicating even heat sealing.

#5 Do NOT put any grease or dielectric or paste of any sort inside the terminal. Bare tinned wire to bare tinned terminal, heat seal, done. Now it's fully water proof....

Marine Wire Termination


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So this bilge pump will always run before the other bilge pump will run and every time it runs, the shower sump pump will run. If you're away from the boat and the shower sump pump fails, does the bilge pump keep running (shower sump overflows back into the bilge) until it burns out?

Or is this second pump on a manual switch?

Ted

Here's a great online website dedicated to proper techniques of marine repairs and maintenance.
https://marinehowto.com/

dhays said:

What is a good way to splice the wires in the bilge area? They shouldn’t be wet, but they should be able to get wet if you follow me.

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If 12V is allowed to get into the bilgewater a lot of damage can be done very quickly via Stray Current Corrosion.

The +12V side MUST be kept out of the bilgewater.

I would want a separate switch for the additional bilge pump so it could be turned on and off as needed. The wires can be joined at the switch. You can buy adapters to allow two connections to a blade terminal.

Terminal strip outside of the bilge if you have to make some sort of 3 wire wye connection. No soldering, no electrical tape, and no ScotchLocs!

dhays said:

This is a very basic question and I feel kind of silly asking but...

I have a dry bilge pump I want to install. It is simply a low capacity, and low profile pump designed to get out the last bit of water from the bottom of the bilge that the regular bilge pump doesn’t get.

I don’t want to create another thru-hull so I am going to run the outflow from this into the shower sump where the shower sump pump will pump it overboard. I also would like to put in on the same electrical circuit.

I want to splice the + and - of this new bilge pump into + and - wire for the shower sump pump. So my question is this...

What is a good way to splice the wires in the bilge area? They shouldn’t be wet, but they should be able to get wet if you follow me.

Click to expand...

My rule of thumb is if bilge pump connections can't be made 18" or more above the base of the pump, they should be submersible/waterproof. As others have noted terminal strips and ring terminals are ideal if they can meet this criteria. This is especially critical for high capacity pumps, but truly applies to all bilge pumps, including drying pumps. The cascading approach is less than ideal, but marginally acceptable if that's not your primary pump.

See Bilge Pump Systems; Design and Installation | Steve D'Antonio Marine Consulting for bilge pump installation details. And Crimping Etiquette | Steve D'Antonio Marine Consulting for crimping/solderless connector etiquette.

Thanks to all the suggestions. Let’s see if I can clarify some things....

The bilge pump is only a drying pump, to use Steve’s terminology above. It is not the primary bilge pump in that location but is only designed to get the little bit of water that the bilge pump leaves behind.

Normally I like terminal strips and jumpers, as was suggested by some above. In fact, I have the same terminal strip and jumpers that HopCar linked above waiting for me to install it for another low power splice job I am going to do. That is in a dry location however.

Ted, yes, this bilge pump would generally run before the main bilge pump would run. You are correct that if my shower sump pump failed, then that drying pump would run continuously until it burned out. Putting a separate switch there somewhere to be able to turn it off would be a good idea.

Gallenharmon, thanks for the link reminder. Silly me, I didn’t check out CMS’s website before asking the question.

CMS, thanks for the tips. And I reread the article that you linked. It had been a while since I have read it.

Again, I am not looking to do just a butt connection but want to take one + wire and send it to two wires. I will check to see if there is a place above the bilge where I can use a terminal strip, but if I can’t, and have to make that connection in the bilge, any specific suggestions?

Edit: I just found that a step down butt connector could be used to connect one wire to two wires. That likely would be my best bet for use in the bilge.

dhays said:

Edit: I just found that a step down butt connector could be used to connect one wire to two wires. That likely would be my best bet for use in the bilge.

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I don’t think the heat shrink/adhesive step down butt connector will seal around the figure 8 shape of the two wires. You are best to stay in a dry location and use the terminal strip, at least then you can see the effects of any moisture or corrosion.

Is This going to run off of the Bilge pump float switch? If so, how will it not shut off when the bilge pump does? Does it have it's own sense switch? As for connections, Use the terminal strip method if at all possible. I have tried the step don type of connecter, with limited positive results, in wet environments.

gallenharmon said:

Here's a great online website dedicated to proper techniques of marine repairs and maintenance.
https://marinehowto.com/

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That's CMS's website who posted 2 posts above yours. Same guy, same great advice!

Island Cessna said:

I don’t think the heat shrink/adhesive step down butt connector will seal around the figure 8 shape of the two wires. You are best to stay in a dry location and use the terminal strip, at least then you can see the effects of any moisture or corrosion.

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I agree with the above concerns. I would make very significant efforts to keep any wire splices out of possible contact with bilge water. Once salty bilge water hits a positively energized terminal/wire stray current corrosion can run rampant and do serious damage in a very short time.

Perhaps you can extend individual wires with high quality adhesive lined butt splice connectors so that you can make the other connections where you can be sure bilge water will never contact a terminal that is not positively isolated from the water?

Ken

there is a better way than even the heat sealed butts:



and:



Most bilge pumps sold have short lives. Make the replacement exercise faster.
The carlon box, mounted hole DOWN, with the stock, gasketed cover, becomes a submersible, dry box.
I've used this method for years in very wet boat bilges.
Yes, use the sealed ring terms for the cinch term. strip if you wish.
Enough wire service loop to pull the terminal strip out a bit for work. BUT, it sits inside the box, loose.
No need to seal the bottom hole.
Try to get the system up high, like a couple feet above nominal "high water mark" in the bilge.

Mischief said:

Is This going to run off of the Bilge pump float switch? If so, how will it not shut off when the bilge pump does? Does it have it's own sense switch? As for connections, Use the terminal strip method if at all possible. I have tried the step don type of connecter, with limited positive results, in wet environments.

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It has its own sensor and pump.

I spent a long time looking at the situation again on Saturday. The "best" way to do it would mean trying to run a new pair of wires from the pilothouse down to the bilge. It shouldn't be as hard as it might otherwise be due to some well designed wiring runs. Even so, it still wouldn't be easy. I will continue to explore the options. I think a step down connector may work if I do it high enough. I could use a terminal strip, but I'd rather not use that in an area anywhere near where they may be water.