The surge protector says:
Suppressed Voltage 330v
Electrical Rating 120VAC
Not sure what this means.
It might appear that there is a huge difference between the nominal operating voltage and the suppression voltage level on devices such as this, but you have to understand how these levels are measured.
A.C. power line voltages are most often expressed as a kind of electrical average value known as r.m.s. (root mean square). Because the power is in the form of a sine wave, the
peak positive and negative values which are reached during each cycle of the sine wave are considerably higher - 1.414 times the r.m.s. value.
Thus your 120V power from a wall outlet has a peak value of about 170 volts. Similarly, the 240V power supplied in Britain has a peak value of just under 340 volts. That's before we allow for the fact that the nominal 120V or 240V r.m.s. supply could be 10% or so higher during periods of low loads. Other factors also mean that the suppression level has to be set rather higher.
So as you can see, your existing unit has a suppression voltage level which is already
below the peak voltage of the sinewave on a British 240V r.m.s. supply. The suppressors would be trying to suppress what they saw as an overvoltage the whole time the unit is plugged in - At least until a fuse blows or the suppressors themselves burn out from excess dissipation.
With regard to the quality of power, it is quite "clean" in most of Britain compared to many other parts of the world, although there can be localized issues. High frequency switching transients and general noise are more likely in industrial areas; rural areas tend to suffer more from brown-outs in bad winter weather due to the prevalence of overhead cabling.
