MOISTURE THE ESSENCE OF WETNESS

摘要

Water damage to wiring is much more common than you'd think and there are ways to detect it when conducting routine maintenance as long as you record the electrical fundamentals of each systemrnyou look after and compare these results over time. As water penetrates the sheath what you're going to get first is noise on the wire indicating high frequency leakage between the conductors. This is because water conducts electricity much better than PVC. You'll also get greater impedance (this may not be measurable, even on an oscilloscope) and the level of isolation will fall. As the copper corrodes you'll get increasing resistance and a lot more noise. In the end you'll get false alarms. If you know there's a wet run in your installation use a gel-filled cable. And if you lose a cable run to corrosion, reinstall with gel-filled stuff. You can run gel-filled cable in a drainpipe and it will never die.