Although it looks ugly, this PVC bushing is one part of a fairly watertight (although only tested to 4 meters) electronics housing made from a 3″ PVC tube. Water did not enter through the wires, the epoxied section, nor the rubber seal.
Start by measuring out all the wires, with plenty of extra length for both inside and outside the housing.
One secret is to strip the wires (and if you’re really serious, to use solid cored wire instead of stranded) so that any water that enters the jacket on the wet side will hit epoxy instead of travelling inside the housing.
Cut a ring of plastic (e.g. from a milk jug) to wrap around the wires.
Hot glue the ring to the PVC, and then hot glue the space around the wires. This doesn’t need to be watertight — just epoxy-tight. This will help contain the epoxy until it sets.
Since the heat from the epoxy curing (or a poor glue job) can result in an epoxy leak, be sure to hold the bushing over a disposable surface of some kind. Notice that the funnel-end of the bushing is up, which will help us fill the bushing without getting epoxy on the wiring.
Time to mix up the epoxy and go.
Fill slowly, making sure to completely fill the area around the exposed wires. Watch for leaks, then let it cure overnight.
Two other important tips.
- Make sure you use a no-hub coupling for your seal, not a “flexible PVC coupling”; the no-hub coupling will need to be slightly stretched over the pipe, which forms an airtight seal.
- Don’t use vaseline, because it will begin to dissolve the rubber. Use a silicone grease to lubricate the seal.