On 26/08/2019 14:03, Robin wrote:
On 26/08/2019 13:42, dennis@home wrote:
On 26/08/2019 12:19, Robin wrote:
On 26/08/2019 12:07, dennis@home wrote:
On 26/08/2019 11:56, Robin wrote:
On 26/08/2019 11:31, dennis@home wrote:
On 25/08/2019 23:08, Robin wrote:
On 25/08/2019 21:50, wrote:
On Sunday, 25 August 2019 19:59:32 UTC+1, ARWÂ* wrote:
A load of ******** here for you to read and forget
https://professional-electrician.com...d-as-standard/

"a relatively low-priced and widely available safety item"

low priced??

And isn't there a bit of a fire risk having something that goes
pftttt in a consumer unit? In the top photo it's wired across
the main switch and not even fused down



like many (most?) such it comes built in fuses so needs no
additional overcurrent protection.



You would think it should handle thousands of amps or its not
going to do anything useful.


They can handle 10s of kA - but only for /very/ short periods.

The overcurrent protection is to protect the cables and SPD against
faults.



The company fuse should protect those.
Typically its 100A, mine is only 80A though.
Obviously if the SPD you buy specifies less then you need something
extra to protect it.


1.Â*Â*Â* You may be happy to risk a faulty SPD taking out the "company
fuse". Others wouldn't.

2.Â*Â*Â* Some SPDs specify maximum overcurrent protection of less than
80A - including the one in photo (63A).


Then they are the wrong ones to use in that CU, unless you don't mind
your supply being reduced to 63A and you fit another fuse/breaker.


You have misunderstood how SPDs work.Â* They are in /parallel/ with the
circuits they protect. So an SPD which needs a max 32A MCB can happily
sit in a CU and protect 100A loads.Â* See the BEAMA guide - link in one
of my earlier posts.

It can but MCBs and RCDs have coils in them so don't expect the same
surge protection if the surge current has to traverse breakers.
To work well, they need a low impedance at a higher frequency than mains
so even small coils will have an effect.