apologies if you are already aware of this but with respect to the x5 or greater test current introduced in the 18th, Hager have advised that their RCBO units are manufactured to the 2017 amended version of BSEN61008/9 which permitted disconnection within 40ms at 250mA. Thus they advise testing at x 5 on both sides with the instrument set for 50mA on the variable range.
