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Watertight cable junctions

Working with installations in and under water at illutron, we often need watertight cable connections.
Commercial products exist for this - But they are very expensive - And can be hard to get to in rural conditions. 

The watertight connectors where used to wire up the installation "Lotus Illutronica" in the lake of Skanderborg Festival in 2009.

We have devised a way to connect cables simple, cheap and reliable using standard plumbing parts.
Parts that are available anywhere. 

You need

  • 1 pipe union
  • 2 pipe inserts
  • 2 electrical fittings 

Make sure the electrical fittings fit into the pipe inserts. 
We are using M20 fittings, that fits nicely into a ½ inch pipe thread. 
Mount the two inserts in the pipe union. I use old fashion jointing compound and Flax / hemp. 
IMG_5039 IMG_5040 

The jointing compound and hemp works fine on the electrical fittings too. 

Tighten the fitting well in the pipe insert, but be carefull with the plastic ones.

Run each of the cable ends through the electrical fittings. Join the cable ends.

Connect the pipe union and tighten

Cooking oil 
Fill up the pipe union with regular cooking oil - If you want extra extra security against incoming water or need to operate in high pressure enviroment (>5 bar = below 50 meters of depth)

Tighten the fitting around the cable to seal and give mecanical strength.

Thats it

Very simple and reusable. We have use this setup for extended periods without failure. 
If maintenance is needed, it is possible to take the joint apart and put it back together easily. 

It is possible to fix broken cables in open sea conditions - You just need basic plumbing tools. 


2 pipe inserts á 3 €
2 fittings á 0.5 €
1 union á 10 €
€  6.00
€  1.00
€ 10.00
17 Euro