I have a condo neighborhood, where each house and the club house has post lights with buried UF, last year they had a tree removal company remove some trees by the entrance and damaged some of the cables, well they fixed them by just splicing them and using just electrical tape, I have tried to let me re do the whole mess in pipe, but as with many don't want to spend the money, so there having me meg them and only fix the ones that show below 2 megs, what is funny is I have one tripping the breaker but only reads 2.7 megs, the only way I can explain it, is carbon flash-over, there must be enough carbon tracking that any transient voltage spike will cause a flash-over into a fault, now a 1kv or higher megger will probably show this cable as a fault, but the one I have is only a 500 volt megger.