It aint good for the wire or the devices downstream. The copper goes dark and can cause high resistance terminations.
In Auckland with OHUG conversions from the last 15 years, sometimes drip loops were not provided and water gets in the actual cablecores, via the linetap, corrodes the copper and in case of 3 phases blows up the main switch PDL/HPM 60 or 80 Amps versions where the phases are quite close together.
Also problems with direct connections to Sangamo S 200.16 and 31 meters which have alloy terminations and water will corrode the terminals and cause a phase to neutral flashover, BANG !! fuse gone, power off in the house. sometimes the green gooiee stuff comes out of the earlier TPS cables as a warning of problems ahead.