Better Together - Care and Maintenance of Batteries and Modules for Emergency Lighting

Self-contained emergency lighting is supplied via a module/battery pack arrangement and the battery content consists of cell varieties from 2.4V to 12V DC. The type of batteries for emergency lighting encompass Nickel Cadmium, Nickel Metal Hydride and Lead Acid.

All of the above mention battery types are regularly used in self-contained emergency lighting either integrally or remote to the luminaire. A maximum ambient temperature (ta) of 25 degrees centigrade is the recommended norm for most luminaires and the emergency luminaire should be mounted in an area where the ‘ta’ (25 degrees C) is not exceeded as the batteries especially are temperature sensitive. If their maximum temperature (usually 45 degrees C) is continually exceeded, their useful life will be reduced. Most batteries have a design life of 4-years but this duration is very much based on attended install conditions, the optimum building environment and effective maintenance regimes.

When batteries are first installed they will be in a discharged ‘storage’ state and it is imperative that after an initial uninterrupted charging period of at least 24-hours they are completely discharged. This process should be repeated at least twice more before the site is handed over. Proper initial cycling of the batteries is very important to ensure they reach full capacity.

Partial charging and discharging (especially over a prolonged period of time) is very likely to result in both reduced battery and emergency lamp life. Care should be taken, especially under site conditions, not to continually cut mains power.

Regular testing of the emergency circuit is an important factor in ensuring reliable operation. However, equally important is the connection method of the luminaire to the mains supply. 
One of the following illustrated circuits must be employed when installing the luminaire. Not to do so could result in serious failure of components when maintenance is carried out. The use of one of these circuits will also make it easier to carry out the monthly ‘operation tests’ as required under BS5266 (see test record sheet).

The emergency luminaire requires TWO power supplies, one to run the mains lighting fed via normal switching and the other to run the emergency side fed from an UN-SWITCHED supply. This keeps the batteries permanently on-charge. The emergency mains terminal block, labelled UN-SWITCHED SUPPLY could be part of a 4-way block, or may be a separate fused terminal. The fuse for the emergency supply is rated at 1A unless otherwise labelled. The neutral and earth connections can be common to both the switched and un-switched supplies.

To simulate mains failure, both supplies to the luminaire MUST be broken simultaneously. Single pole key-switches or separate sub-circuit fuses or MCB’s for the emergency supplies must NOT be used. Adherence to this method is mandatory regardless of other switching arrangements such as two-corridor lighting. Steps should be taken to ensure the emergency

supply is NOT inadvertently interrupted at any time. All switches associated with the emergency supply should be situated in a position inaccessible to any unauthorised person or to be tamper-proof and/or re-tractive. All such switches should be suitable identified.

IMPORTANT:

Under NO circumstances must the supply to the emergency gear (un-switched supply) be removed while the luminaire is being powered by the standard control gear (switched supply).

Normal and emergency supplies must be connected to the same phase.

When servicing the luminaire isolate BOTH power supplies AND the battery pack (-VE ‘black’ lead first).

Be careful when handling the battery pack not to short out the terminals with rings or watch bracelets etc.

Replace battery pack ONLY with a complete pack of the same type. NEVER replace a single cell in a pack.

High Frequency (electronic) ballasts that detect lamp failure are unable to distinguish between a lamp failing and the change back to mains from emergency operation. When this happens the ballast may shut down and the lamps not operate. To reset the ballast it will be necessary to interrupt the supply from the mains ballast for a few seconds. The installation should incorporate a facility to do this.

Do not ‘Insulate Test’ electronic circuits.

All self-contained emergency luminaires will be supplied with an emergency Test Log and this log should be updated to show both the initial ‘commissioning’ of the battery and module and all future tests/maintenance activity.

When batteries are replaced the new sets should undergo the same initial cycling procedure as indicated herein.