Reliable way to join wires submersed in water

Thread Starter

AlbertHall

Joined Jun 4, 2014
12,157
I need to join a two conductor cable - 12V, 1A. The join will be submersed in 1m of rainwater.
I need a reliable way of doing this, please.
 

Reloadron

Joined Jan 15, 2015
6,979
If I could not avoid it I would consider waterproof heat shrink. I would also overlap it a few times. I would try the Marine Grade stuff. Next would be a hermetically sealed connector but waterproof heat shrink first. At a 1 meter depth the pressure shouldn't be an issue.

Just My Guess
Ron
 

JohnInTX

Joined Jun 26, 2012
4,694
Try the stuff used for underground lawn sprinklers. There are several styles from RTV filled crimp terminals to wire nuts that you snap into a grease-filled tube and snap closed.
 

Lo_volt

Joined Apr 3, 2014
275
When my father sold submersible pumps, he always kept a can of 3M™ Scotchkote™ handy. It is rather expensive, but very reliable for submersed electrical connections.
Try searching for "heat shrink tubing with sealant". These add something akin to hot glue to seal the ends of the joint after shrinking.
 

Jon Chandler

Joined Jun 12, 2008
390
Something that works well for round cable, even submerged dozens of feet....

Roll a couple tight-fitting o-rings on each end of the cables to be spliced, and put them about one inch and two inches back from the edge of the cut outer insulation (i.e., on the intact part of the cable jacket). Make the splice, then cover the splice, the o-rings and a couple inches past the o-rings with adhesive-filled heat shrink.

The o-rings give the adhesive-filled heat sinking a good area to seal.
 

Ya’akov

Joined Jan 27, 2019
6,575
It is 3A mains cable - two cores inside an outer insulator.
These, or connectors like them are very easy to use and completely waterproof when applied properly. The linked ones have three ports but it doesn't matter. They are filled with a mineral grease and when crimped, the grease fills the insdoie making water ingress impossible.

It's best to use parallel(ish) jaw pliers like Channelock-style adjustables, when crimping them. Actual old-fashioned Sargents but it's not necessary.
 

Ya’akov

Joined Jan 27, 2019
6,575
To add to the above, if you want belt and suspenders, you can use marine grade adhesive filled heat shrink over them. Though I don't think it would actually improve the watertight aspect, it would provide good mechanical strength. The 3:1 type is best if you can find it.

Obviously, you'd want to line the connectors up so the were linear in the tubing.
 

MrSalts

Joined Apr 2, 2020
2,376
These, or connectors like them are very easy to use and completely waterproof when applied properly. The linked ones have three ports but it doesn't matter. They are filled with a mineral grease and when crimped, the grease fills the insdoie making water ingress impossible.

It's best to use parallel(ish) jaw pliers like Channelock-style adjustables, when crimping them. Actual old-fashioned Sargents but it's not necessary.
Those connectors are exact knock-offs of 3M Scotch-loc 316L and 3M Scotch-loc MGC for "LOW VOLTAGE LANDSCAPE AND IRRIGATION" systems. That is, 12vDC to 24v AC. I would never use or recommend a low-voltage connector designed for surface or burial for use on mains voltage in a submerged applications. There are no voltage ratings on the Chinese-made, Amazon-listed part. I wouldn't trust my kids reaching into a koi pond (or even my koi fish in the pond) to an unsealed little capsule of a Vaseline in a snap-fit plastic case.
 

MrSalts

Joined Apr 2, 2020
2,376
Look for the phrase, waterproof pigtail. The pigtail joins bare wires to a waterproof connector (usually with screw couplings with o-rings). They are commonly used for pumps on fountains in large ponds/lakes.
 

Ya’akov

Joined Jan 27, 2019
6,575
Those connectors are exact knock-offs of 3M Scotch-loc 316L and 3M Scotch-loc MGC for "LOW VOLTAGE LANDSCAPE AND IRRIGATION" systems. That is, 12vDC to 24v AC. I would never use or recommend a low-voltage connector designed for surface or burial for use on mains voltage in a submerged applications. There are no voltage ratings on the Chinese-made, Amazon-listed part. I wouldn't trust my kids reaching into a koi pond (or even my koi fish in the pond) to an unsealed little capsule of a Vaseline in a snap-fit plastic case.
need to join a two conductor cable - 12V, 1A. The join will be submersed in 1m of rainwater.
I need a reliable way of doing this, please.
 

SamR

Joined Mar 19, 2019
4,408
I've had great success with the heat shrink tubing with the interior adhesive in seawater. It doesn't need to be on each wire, just over the spliced area. I used a spliced cable to an OMC Electrashift Outdrive that stood up not only to seawater but also to the extreme forces of water velocity @ 50 mph and vibration for many years. In fact, it was still working when I retired the boat years later. If in doubt, double shrink wrap it overlapping the first wrap edges.
 
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