SPD's - are they required or just nice to have?

[SUNRAY]

I saw the result of a radio hams shack supply using a 4 mm² earth cable from the CU to shack when the PEN was lost, little balls of copper, OK with a 65Ω earth rod no problem, but the 4 mm² was bonded to the earth bar in the shack which was connected to 4 earth rods with bare copper tape between them for the radio transmitter so was better than my meter could measure, I would say less than 1Ω. He had realised there was some thing wrong, turned off main isolator to house, and called me on 2 meter as this had not stopped the earth wire melting.

It was caused by some road works, and the DNO said it was impossible, but responded very quick, and the radio ham was only person in street not to loose equipment, since he had turned off the main isolator before his wire burnt out. Why the person wiring his shack had used twin core SWA and not used the SWA as earth I don't know.

But had the supply been PME and actually had multiple earth rods it could not have happened, but TN-C-S is not always PME.

Yes they do respond quickly in situations like that:
https://www.diynot.com/diy/threads/a-real-moan-tonight.552183/

 

[endecotp]

How many domestic installations have suffered damage from surges, excluding lightning. Are spd's a solution to an imaginary problem.

I have been considering building some sort of gadget to record how many "surge events" I get.

E.g. look for a L-E transient of more than 400 V and turn on a light, with a manual reset. Correlate with local thunderstorms?

 

[mattylad]

But what if you get further surge events before you can reset it?

 

[JohnW2]

But what if you get further surge events before you can reset it?

I'm sure that it would not be beyond the wit of man (or endecotp) to get his gadget to count, or even 'log' (with timings), the number of surge events'.

Kind Regards, John

 

[endecotp]

But what if you get further surge events before you can reset it?

I’m more concerned about how to test if it works at all.
It’s a bit like making your own seismometer in the basement, in this country.

 

[JohnW2]

I’m more concerned about how to test if it works at all. It’s a bit like making your own seismometer in the basement, in this country.

Given the uncertainties about how 'real', or how common (or rare) this issue is, if it were me I think I would start by configuring my gadget to detect transient excursions to voltages not much over nominal - maybe as low as 260V or 270V - otherwise I might have to wait a few lifetimes for the light to come on!

If I did detect anything by doing that, I would then gradually increase the 'threshold voltage'.

One issue might be that some of these transient surges might be incredibly brief (microseconds), and hence not all that easy to detect.

Kind Regards, John