On 19/11/2019 10:10:28, John Rumm wrote:
On 18/11/2019 20:56, Fredxx wrote:
On 18/11/2019 17:13:12, Tricky Dicky wrote:
In my earlier post I mentioned my BCO insisted I fit a Surge
Protection Device (SPD). The item arrived today and because the Surge
Devices web site has some information but not the full install
instructions, I have scanned the instructions in case anyone else was
thinking about one and would like further information.

https://www.dropbox.com/s/a8nv5zyk29...anual.pdf?dl=0


Is this not a contradiction:

Â*Â* "Connect to a 32A MCB b or c curve"
and
Â*Â* "You only need one arrester per board and all your outgoing
circuits on that board will be protected"

I thought the device relied on tripping a 32A MCB to disconnect that
specific circuit? Or will it take the company fuse with it?

No, neither of those. The SPD would function even without the MCB. The
way it works is to "snub" the transient (either L to N or L/N to E) -
i.e. it passes a current limiting the rise in voltage. The downstream
equipment should be none the wiser, and carry on operating as normal.

The purpose of the MCB is just for the protection of the SPD - should it
fail short, or attempt to act on a significant surge that would result
in its destruction. With a 32A C Curve MCB, it can pass up to 320A for a
very short duration to effect the suppression (or =160A for a type B),
and beyond that the MCB would operate removing from the supply.

Thanks for the explanation.

Looking at some more info and their characteristics at raised voltages I
do wonder how effective these are at preventing high voltage transients.