443.4.1 joke or what

buzzlightyear · Apr 26, 2022

what is with the IET regarding 443.4.1 against transient overvoltage
1) serious injury to lose of live ( sitting in a field where lighting strikes)
2) failure of safety services ( not got your hard hat on in a field)
3) significant financial or dater lose ( run over by a cow using your phone)
and the best one hey customer can you sign this just in case all above might happen.so now they have taken the map of UK away showing where you on the map no drawing pin required .

Dartlec · Apr 26, 2022

The previous system was a mess, so anything is an improvement I guess.

Kirsty from Surge Protection Devices has put together a useful sheet here though no surprises that it's weighted towards installing them.

Her view is that a mains powered smoke alarm would be covered under item 2 (Though if it had a back up battery I'm not sure if that's the only interpretation)

If the situation arises where the client doesn't want the extra cost of one I will probably rig up some sort of sheet that the client can sign when changing a consumer unit, to be kept with the certificate. And I'll note it on the EIC.

Though to be fair they usually only add at most £50 so I will be mostly putting them in unless there's a good reason.

pc1966 · Apr 26, 2022

That page by Surge Protection Devices is good, as it also point out that if you are fed from overhead supply lines you really ought to install a type 1 SPD as you might get a lot more surge energy than usually induced on under ground cables, etc.

The original 18th method was way too complicated as in practically no situations would you know the lengths and categories of cable (i.e. underground, or overground, maybe wombling free) so the risk computation was impossible to do. I do think they should have kept in the map showing lightning density, but that is more for curiosity then actually applying it.

Really SPD should just be fitted every time, cost is now low compared to the CU change and folks have more stuff at risk than they might think of. I would guess most homes have at least £3k new-replacement worth of stuff always-on (cooker, fridge, gas boiler, smoke alarms, PIR lights, wifi router/modem, TiVo box, etc, etc) that are now controlled by electronics and in commercial/industrial settings possibly more (as well as the likes of emergency lighting) so the £50 SPD is looking like reasonable protection.

We don't really grumble about the RCDs or RCBO/MCB cost being unreasonable for socket protection now, though AFDD are still eye-watering in price for a whole board, and they too have some limits in terms of surge voltage. Though I suspect damage to that sort of well-engineered product is fairly limited unless you have a very local strike or overhead lines involved.

I have seen a strike over my parent's town (Arbroath, hardly a high risk area) when young and that a good few filament lights in various homes and commercial buildings went out instantly!