On Wednesday, February 8, 2017 at 6:20:05 PM UTC-5, James Wilkinson Sword wrote:
On Wed, 08 Feb 2017 23:14:02 -0000, trader_4 wrote:

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.

In the UK I cannot think of where there would be an exposed HV wire and a 240V wire in close proximity. Usually the HV wires are underground and insulated up to the transformer, then the 240V is either also underground and insulated, or with older houses where the wires were inserted above ground into the roof, they are the only ones bare.

If you really have underground distribution lines running around
out in the country, it could explain why you're paying so damn
much for electric. Here the common approach in rural areas is
to have poles with the primaries at the top, then a pole mounted
transformer that drops it down to 240V. IDK what all the primary
voltages are, but think typical is probably ~10K. Underground is
in cities, towns, more developed subdivisions with newer 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.

Not LED lightbulbs, they're too cheap to have that protection. And my computer is not protected against 5 second outages. The system shuts off and corrupts the hard disk.


You said "spikes" of 30 volts. A spike is not a 5 sec outage. A PC
would never even notice a 30V spike. And while a surge protector
can protect against spikes of thousands of volts, a surge protector
is not going to guard against a 5 sec power outage.