These are primarily used by the public in disabled refuge areas, which should be provided on or near all protected stairwells to allow the orderly evacuation of people requiring assistance.

Refuges are not just for wheelchair users, but for all people who may slow the egress of evacuees,    and typically refers to those who cannot walk 200m without stopping or aid.

The unit fits in a standard UK style double socket back-box and has a green flashing button  to attract attention, especially in low light environments.