Why are the two poles of the Hager SPD rated differently

[spud1]

So I was installing a new split load Hager DB (with the integral SPD) and noticed that the SPD cartridges connected across the neutral and line poles of the SPD were rated differently. Is there a reason for these different ratings?

Spud

 

[spud1]

Is that the main switch?
So if the main switch is off, there’s no surge protection.

Would there be any need for surge protection if the main switch is off

 

[spud1]

Is that the main switch?
So if the main switch is off, there’s no surge protection.

Would there be any need for surge protection if the main switch is off?

 

[Deleted member 26818]

Could a surge damage the main switch?

 

[spud1]

Could a surge damage the main switch?

Possibly I guess? But how much is a main switch to replace?

 

[richy3333]

On their website Hager show fitting the SPD after the main switch protected with a 32A MCB. 6mm tails. Thats how Hager technical have talked me through it in past years.

Hager - Surge Protection Kit Videos - https://www.hager.co.uk/archives/videos/52326.htm

 

[freddo]

I have a Hager surge module here, it states fuses/MCBs can be omitted if the supply fuse is less than 125A. I have it on a 63A HRC fuse though.