I'm trying to replace a pir which activated a now inwanted low wattage external light with a proper security light including an integral pir. The existing wiring allows for manual override by a normal domestic light switch inside the kitchen. Two externally run cables end at the existing chock bloc to the old pir, each with line neutral and earth. However the new light assembly reveals one white cable running from the pir into the bloc. Could anyone offer me either instruction or a wiring diagram for this please?