when a 13A socket is connected to a lighting circuit in a loft, it is very often so that a "wallwart" power supply (which only plugs into such a socket) can be used. Very often for a TV aerial distributor. Occasionally for an alarm, or other low-power accessories, such as a charger for a cordless tool
is also handy for a working lamp on a wanderlead
is also handy for a working lamp on a wanderlead