The Brighter Choice
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 regularly 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?
There are four widely used ways to test emergency lighting.
• Manual test
• Self-test
• Wireless addressable test
• Wired DALI addressable test
Each of these test methods is discussed below, but to fully understand them it is necessary first to understand how an emergency fitting should be wired.
How should emergency lighting be wired?
To understand these 4 test methods it is necessary first to understand how an emergency light fitting is wired. Note that the remarks that follow apply to self-contained emergency fittings, not to emergency fittings linked to a central battery system.
Terminal wiring diagram for a class I 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. Note that any switching of L SW must 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. This is installed on the permanent live supply to an emergency fitting that is designed to be manually tested. When actuated it isolates the emergency fitting, thus simulating a power failure.
The 4 commonly used methods of testing emergency lighting are as follows:
• Manual testing. This is a very common form of testing and is appropriate for smaller installations. 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.
The benefits of manual testing are that the fittings are the lowest cost to purchase.
The drawback of manual testing is that there is the manual, labour intensive (and therefore expensive) monthly testing, recording and reporting process to be done. Apart from the cost, there is the risk that this is overlooked or not completed thoroughly.
Manual test button.
Pressing this performs the same function as a key-switch, disconnecting the permanent live supply, thereby forcing the fitting into the battery operated state.
• Self-testing .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.
The two significant drawbacks of self-testing are that, first, there is no facility to schedule the testing – so it might be carried out by the fitting at an inconvenient time, such as in the middle of a lesson (in a school), or in the middle of medical examination (in a surgery or hospital). Secondly, the processes of recording and reporting are not automated, so some labour cost will still be incurred every month.
• Wireless addressable test. These systems (for example, Casambi and Inventronics’ HubSense) use wireless mesh networking technology to enable emergency fittings to communicate with an app (on a smart-phone or tablet). In accordance with a testing schedule that the installer sets-up via the app, each fitting tests itself and then communicates the results to the app where the responsible person can see the test results and the status of each emergency fitting.
Wireless addressable test has many advantages. First, it saves the labour of manual testing. Secondly, it eliminates the risk that routine testing is overlooked. Third, it carries out tests according to a pre-arranged schedule, so that testing can always take place at a convenient time (not in the middle of a class, in the middle of a doctor’s consultation or while a film is showing in a cinema). Fourth, it automates record keeping and fault reporting. Fifth, it does not require additional wiring, so is typically quick and easy to install.
Some additional acquisition cost is involved with wireless addressable test, but in most cases this is quickly recovered as the testing, recording and reporting processes are all fully automated.
Wired DALI Addressable Test.
This is a type of emergency testing that employs a central control point connected to all the emergency fittings in the installation via a DALI network. 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.
Wired DALI addressable test is well suited to large projects, especially those with distributed estates such as hospitals, colleges, university campuses and business parks. It has the disadvantages of increased acquisition and installation costs over other test methods, but for large distributed estates a DALI wired approach gives unparalleled reliability and control.
This table summarises the key features of the 4 commonly used emergency test methods.
