A range of general purpose time switches, which provide a single output circuit. The range includes a simple 24 hour electro-mechanical model, plus two electronic models, which offer 5/2 day or 24 hour and 7 day or 5/2 day operation. All three units fit the GP wallplate and have an identical wiring configuration, allowing systems to be upgraded without the need for rewiring. The electro-mechanical 103 has a timed, off, constant switch, and a thumbwheel which allows early selection of future switching operations. All models show clearly the current state of the output. The electronic units have extra programmes and overrides and incorporate a battery to provide back up of time and programme.