Well, I'll kick off the debate on SPDs. Once again, the emphasis seems to be on domestic (we all, or virtually all of us live in a home of one sort or another) so are the proposals an improvement or not?
An SPD of the sort considered here will not protect against a lighting strike (where the line of ionized gas terminates on the wiring in question)- The currents and voltages are too high to do anything about, short of immersion under a few metres of sea water.
SPDs may, in a limited subset of cases, help against voltages induced by lightning overhead or that terminates some distance away- though only for a limited range of radii - far away events would have had no effect anyway, and too near and the over-voltage is too extreme.
So the question reduces to calcualting how big an effective capture area the local LV network represents.
That ought to have units of square metres, so that it can be multiplied by a strike density per area per year, to get events per year.
An SPD of the sort considered here will not protect against a lighting strike (where the line of ionized gas terminates on the wiring in question)- The currents and voltages are too high to do anything about, short of immersion under a few metres of sea water.
SPDs may, in a limited subset of cases, help against voltages induced by lightning overhead or that terminates some distance away- though only for a limited range of radii - far away events would have had no effect anyway, and too near and the over-voltage is too extreme.
So the question reduces to calcualting how big an effective capture area the local LV network represents.
That ought to have units of square metres, so that it can be multiplied by a strike density per area per year, to get events per year.
