After my little boo-boo with measurements, I purchased a new Wiska junction box from RS, this time with a little more width and the Sonoff relay fit perfectly! I also picked up some IP66 glands to help secure the wire from the LED strip.
This junction box had a membrane covering each hole, so I pierced a hole in it and fed the table through. The gland then screwed into the threaded hole (what makes these Wiska boxes so great).
I tightened it all up.
Sadly, I didn’t take any pictures of my SWA cable gland process as I did it at lunch time. This was the tricky part of my installation since it required a hacksaw. I found a great YouTube (https://www.youtube.com/watch?v=epmxqFiD9JI) video and followed that as best I could. I didn’t have the “glanding spanners” as recommended, but I made do with pliers. I do plan on using another armoured cable to connect to the other side of the garden, so I’ll take photos of that.
Anyway, with everything installed, I dropped the box in the garden.
You can see the thick black SWA cable and the thin LED cable. I should point out that this is not the final resting place of this box!
The lights look pretty nice in the snow and light the garden pretty well.
This weekend I plan on getting a few metres of SWA and using the small junction box to hook up the lights on the other side of the garden!