Emergency lighting must be designed so that testing of the system can be carried out without interrupting the normal supply. All new distribution boards must now be fitted with a central test unit to provide the facility of testing the emergency lighting system. It is possible that existing boards do not have this facility and therefore would need to have them installed in order to bring the installation up to regulation standard.

We will install these test units at a small cost to facilitate future testing, eliminating the inconvenience of isolating the power when future testing of the emergency lighting is being carried out.

The power will need to be isolated in order to install the CTU so this will have to be arranged at a time most convenient to your business.

Typical Central Test Unit.

Is the above unit installed in your Distribution Board? If not then your installation is not up to regulation standard.

Typical Wiring schematic of an Emergency Lighting Central Test Unit


It is a statutory requirement under the Code of Practice for Emergency Lighting IS3217: 1989, to have a Central Test Unit installed in all Distribution Boards.

‘Each emergency lighting system should have a facility for simulation failure of the normal supply for test purposes. The facility should not interrupt the normal lighting supply to the area concerned. After the test period the emergency lighting system should be automatically restored to its normal state’

‘Generally a test switch with 30 minutes and 3 hour timers to isolate only the unswitched supply to emergency luminaires is provided’

This facility enables the emergency lighting to be tested during normal working hours without any inconvenience to the day to day running of the premises in question.