They are both labelled as an AC22A, but the one with the the SPD is a WS102 which is a consumer unit main switch with a slot to accommodate a balcony busbar allowing it to to secured under output terminals screw heads, whereas the isolator in my photo is the “real” REC switch a WS102-TT with double screw terminals that tighten plates down onto the conductor rather than being a cage clamp terminal.


I presume the TT in the code refers to it being double pole and suitable for a TT earthed installation. If you pay particular attention you will note the main switch with the SPD is marked as a single pole isolator, despite being double pole, whereas the isolator I have posted a picture of is labelled as a double pole isolator. Though in both photos the switch is down, so that’s not obvious unless you look carefully.


I presume the SPD unit has been supplied with a consumer unit main switch rather than a REC isolator on purpose.


I would expect to see two short pig tail conductors with fork crimps on both ends allowing them to be secured in the balcony busbar slots under the terminal screw heads on the output, the bottom of the switch with the incoming supply connected feeding into the top terminals.


What I cannot see is how they the main switch can be connected to the SPD using busbar.


Andy Betteridge 

They are both labelled as an AC22A, but the one with the the SPD is a WS102 which is a consumer unit main switch with a slot to accommodate a balcony busbar allowing it to to secured under output terminals screw heads, whereas the isolator in my photo is the “real” REC switch a WS102-TT with double screw terminals that tighten plates down onto the conductor rather than being a cage clamp terminal.


I presume the TT in the code refers to it being double pole and suitable for a TT earthed installation. If you pay particular attention you will note the main switch with the SPD is marked as a single pole isolator, despite being double pole, whereas the isolator I have posted a picture of is labelled as a double pole isolator. Though in both photos the switch is down, so that’s not obvious unless you look carefully.


I presume the SPD unit has been supplied with a consumer unit main switch rather than a REC isolator on purpose.


I would expect to see two short pig tail conductors with fork crimps on both ends allowing them to be secured in the balcony busbar slots under the terminal screw heads on the output, the bottom of the switch with the incoming supply connected feeding into the top terminals.


What I cannot see is how they the main switch can be connected to the SPD using busbar.


Andy Betteridge