I've been using them for about ten years. I've never had a failure. You do tape the area where you've removed the UF jacket. I've dug up splices several years old to find them in perfect condition.
No problems with ground faults. These are large nuts filled with some type of silicone, which even after years doesn't break down, and prevents water entry
One common situation I've had is replacing broken or rotten residential lamp posts. Invariably the existing uf feeder gets destroyed in digging out the old post. I use these wirenuts in the ground to splice on a new length of cable to feed into the new post. I've had occasion to replace the new posts as well, or adding a second fixture in some instances
Thanks to all for the replies. The splices in question were in fact to feed a light post, but not because the post is rotting.
Epilogue: Since the two cuts were in the middle of a 70 foot underground run, I decided to hand dig just for the splices down to 18" (about ten feet of trench), trim the existing UF line back to cable unaffected by the backhoe and splice in new UF wire using four of the ($11) Ideal UF splice kits from Home Depot.
Materials cost was about $55 all-in. If the line were crucial, I probably would have dug the 70' trench and replaced the line end-to-end. As it is, the line is a seldom-used feed for the lightpole and nothing else - failure wouldn't be a disaster - so I skipped the
70' hand dig.
In retrospect, I spent much more time cutting, stripping and splicing the UF cable than I would have hand-digging the trench. I had never worked with UF before, and managed to give myself a pretty nice gash with a utility knife before I got the knack of stripping the solid outer jacket. Lesson: hand-digging a trench to bury cable just doesn't take that long. If I had done the hand-dig, I would have saved both time and money and would have a better result in the ground right now.
I may have a chance to check this out later. As I said, I didn't splice the cable because the lamp post is rotting, I spliced it because a backhoe hit the cable in two places. Having said that, the lamp post is, in fact, rotting.
Again, thanks to all for your attention and for sharing your knowledge.
Have to admit, that sometimes getting overzealous with a knife to cut uf's jacket has resulted in me damaging the individual conductor insulations, so I understand why it took a while.
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