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A Guide to Emergency Lighting - Testing

BS5266-1 states that emergency lighting should be regularly tested.

How often should emergency lighting be tested?

BS5266-1 states that emergency lighting should be tested as follows:

  • A brief functional test at least once each month
  • A full duration test at least every year
  • A visual inspection at least every year
  • BS 5266-1 also advises that records of all tests and repairs should be kept in a log book.

How should emergency lighting be tested and wired?

There are three widely used ways to test emergency lighting. To understand them it is necessary to understand first how an emergency light fitting is wired. Note that the remarks that follow apply to self-contained emergency fittings, not to central battery operated emergency fittings.

wiring diagram for a class I maintained emergency light fitting.



Terminal wiring diagram for a class I maintained emergency light fitting.



wiring diagram for a class I non-maintained emergency light fitting.



Terminal wiring diagram for a class I non-maintained emergency light fitting.



L SW is the normal mains supply. A normal light switch, or sensor, would usually be on this circuit to enable the end-user to have control over the light fitting in normal operating mode. L SW is always to be wired so that any switching of L PERM will disconnect L SW too, but any switching of L SW will not affect L PERM.

L PERM is the permanent live supply and must have no normal (manually operated) switch or sensor on it. However, a key-switch is permissible and will usually be installed on this circuit. L PERM has two functions:

1.It supplies the power that keeps the emergency batteries charged. That’s why it must not be affected by any switching of L SW.

2.When zero voltage is detected at L PERM it is the indication to the emergency module in the light fitting that mains power has been lost and that battery power must now be switched on.

A key switch example




A key-switch. This is installed on the permanent live supply to an emergency fitting. When actuated it isolates the emergency fitting, thus simulating a power failure.





The 3 commonly used methods of testing emergency lighting are as follows:

  • Manual testing of emergency light fittings. This is the most common form of testing and is appropriate for smaller installations. Most commonly, a key-switch is used to disconnect the permanent live supply (L PERM) to the emergency fitting, thus simulating a power failure. When this is done, if the fitting is working correctly it will switch to battery operation and the LED indicator lamp (which is supplied with every emergency fitting) will switch off. When power is restored to L PERM the LED indicator will switch back on, indicating that the batteries are re-charging. An alternative to using a key-switch is to have a test button on the fitting itself, and this is commonplace on some emergency exit signs and twinspot fittings.

Manual test button functioning as a key switch



Manual test button.

This performs the same function as a key-switch, isolating the fitting from its permanent live supply and thereby simulating a power failure.






  • Self-testing emergency light fittings. Some fittings carry out their own test without human intervention or the need for a key-switch and the associated wiring. A self-testing emergency fitting is autonomous; it operates on its own, conducting the tests required by BS5266-1 at the appropriate intervals without any communication with adjacent fittings or a central control point. Many UK manufacturers use a tri-colour indicator LED to show the status of the fitting after testing with green indicating that everything is working correctly, yellow to indicate an LED fault and red to indicate a battery/charging fault.

Self-test has several benefits. First, it saves the labour of manual testing. Secondly, it removes the risk that routine monthly or annual testing is overlooked.

  • Addressable self-test. This is a type of emergency testing that employs a central control point, module or server connected to all the emergency fittings in the installation either by wire or an Rf signal. Each emergency fitting is allocated an address and at pre-determined intervals the central module initiates a test of each fitting. The central module records the results of the tests and makes them available for the responsible person to interrogate or download.

Addressable self-test is well suited to large projects and large, distributed estates such as hospitals, colleges, university campuses and business parks.

Several different technological approaches to addressable self-test can be taken, including wired (often using DALI as the communications protocol), as well as wire-free using a range of Rf protocols including Bluetooth, Zigbee and other proprietary technologies.

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