What is going on with SPD's and A3

[timhoward]

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That would be the new 443.4.1 See above post for how Napit instructed us to interpret it.

ah but that bit was dropped in a subsequent update. @pc1966 beat me to it - see above.

They rambled on for a bit but made it clear we had no choice but to fit SPD's even in single dwellings

Napit can say whatever they like (I'm a member too btw) but the regs are clear that with the exceptions in the first part of 433.3.1, the owner of an installation can still essentially opt out if they want to. Napit advice at the A2 Expo in Manchester was to get a signed declaration from the owner in such circumstances.

The last page of appendix 16 makes interesting reading, suggesting that more prominence is given to voltage limiting characteristics of an SPD rather than the energy it can withstand. I take that to mean that a Type 2 will still protect equipment if there's a direct lightning strike outside, but may be useless afterwards.
It occurs to me that one could replace a few type 2 modules before the price of a type 1 has been reached.

Of course, if I fit any new CU I fit surge protection. Where possible I add and SPD if adding a new circuit but I won't die on my sword over it. A reality of domestic sparking is that we have to be pragmatic when extending or altering existing installations and decide where we draw the line. At the end of the day, the regs are not statutory (I'll get my coat)