On Wednesday, February 8, 2017 at 5:18:18 PM UTC-5, James Wilkinson Sword wrote:


I can't believe it's that likely for 4800V to get onto a 240V line. Possible, but so rare it's not worth bothering to install protection.

How frequently it happens, can't say, but all it takes is a car
hitting a pole along the road, taking it down, with one of the
primary wires dropping onto the 240V lines that serve homes.



I protect against little spikes, or voltages about 30V under/over what they should be.

Which is something virtually all modern electronics and components
don't need to be protected against. Power supplies will take that
range of over voltage and they all have MOVs to protect against short
spikes that are hundreds of volts or more.