Danlers Ceiling Surface Mounted Plug-In Photocell Switch Reset On Type. Built-in time delay of 1 minute avoids unnecessary switching. For saving lighting energy in offices, factories, sports halls and so on. For surface mounting onto solid ceiling.
This 'Re-set' version switches the lights off when there is sufficient ambient light but requires the wall switch to be operated in order to switch on. In this way the lights only switch on when they are demanded.
Built-in differential ensures the artificial lights do not effect the photocell.