And why was the sensor installed:
A couple have taken legal action after claiming motion sensors installed at their holiday flat in Dorset breached their rights as Orthodox Jews.
Gordon and Dena Coleman said they cannot leave or enter their Bournemouth flat on the Sabbath because the hallway sensors automatically switch on lights.
The couple's religious code bans lights and other electrical equipment being switched on during Jewish holidays.
They have now issued a county court writ claiming religious discrimination. They also claim breach of their rights under the Equality Act 2006 and Human Rights Act 1998 and the case is due to be heard at Bournemouth County Court next month.
The light sensors were installed at Embassy Court in Gervis Road to save money and energy but the couple, who live in Hertfordshire, felt they breached their religious rules.
Dr Coleman and her husband offered to pay for an override switch as a compromise but Embassy Court Management Company rejected this and the couple took legal advice.
They have said they will drop the legal action if an override switch is installed and their legal costs and compensation are paid.
The firm said almost all residents supported the installation of the sensors and taking legal action was the Colemans' "prerogative".
Other residents in the block of 35 flats, who could end up having to pay legal costs, are upset.