DB Surge protector installation SASP-15KA

[LightsOn]

I recently saw SASP-15KA in the ACDC catalogue and for R140 it's cheap insurance.

https://a365.acdc.co.za/Images/spec/SASP%20-5kA%2C%20SASP-15kA.pdf

I see it has a rating of 15kA and 275V and uses MOV's (which arrest surges by simply shorting the supply once the voltage goes above the threshold)

It doesn't say how it should be installed though.
Does SANS specify where it should be installed?
I would imagine it should be installed after the mains isolator. So the neutral output of the mains isolator connects to the bottom of SASP-15KA, and the live output of the mains isolator connects to the top of SASP-15KA ?

[LightsOn]

Using a wire gauge that can carry more than 63A, given a 63A Mains Isolator.

[GCE]

Using a wire gauge that can carry more than 63A, given a 63A Mains Isolator.

An Isolator gives no protection

[Isetech]

On page 302 of SANS 10142-1-(3.01) has a diagram with location of the overload protection device and how to wire an SPD into a single phase system.

[LightsOn]

Thank you very much for your replies! Most helpful

[Andrew_van_Zyl]

I install after main switch and before earth leakage. Shortest possible 16mm2 conductor to earth.
Remind the client to check condition often