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Understanding the characteristics of self-contained (SC) and central battery systems (CBS) – emergency lighting’s two core technologies – is important for any building owner or operator planning their emergency lighting strategy.
Every building will have its own unique set of factors that will ultimately point to one or the other route as being the most appropriate. This section highlights the differences between SC and CBS approaches and some of their features.
A self-contained (SC) emergency luminaire has its own battery. Under normal conditions, this remains permanently on charge via the mains lighting circuit until the power supply to the luminaire is lost and the battery takes over.
All elements of a SC luminaire micro-system, including battery, light source, control unit and any test or monitoring equipment, will either be located within the luminaire housing itself or in a directly adjacent enclosure, connected via short cabling (i.e. less than 1m).
A central battery system (CBS) – also known as central power supply ‘CPS’ or low-power supply ‘LPS’ systems) supplies ‘slave’ emergency luminaires with no onboard battery. Instead, the luminaires automatically draw power from one centralised battery in the building, supported by a charger, change-over devices and alarms should mains lighting fail.
In some CBS installations, several Low Power Supply systems (LPS) are distributed in the building to serve only individual floors or fire protection sections.
As each country has its preferences and regulatory frameworks, CBS can encompass multiple formats with varying features. These can include different testing approaches and functionalities as well as AC/DC power configurations.
Although UPS is not prohibited for emergency lighting systems, its use does require compliance with both UPS and CBS standards.
For further information, Eaton has a white paper on CBS selection. Similarly, an Eaton expert will be happy to discuss this further.
Specific regulations and standards govern how all emergency lighting systems – whether self-contained or central battery unit – are tested to ensure they are functioning as they are meant to.
The owner or manager of the building has a moral responsibility to ensure a thorough risk assessment is conducted, acted upon and continually updated. In most countries, the obligation to implement such a process is enshrined in law.
Testing starts when a system is first commissioned following installation. It then continues periodically during the system’s working lifetime to protect against failure and minimise risk to life. Records that detail all testing events are needed to demonstrate compliance.
There are two main approaches to emergency lighting testing:
Simple, unmonitored luminaires need to be inspected visually. Centrally supplied (CBS) luminaires feature no indication of their status and the system needs to be switched manually to battery mode to check if the luminaires will light up.
A self-contained emergency light can use a simple green LED to indicate only that voltage is applied through the battery charge circuit.
When the luminaire’s test button is activated, it simulates a mains lighting failure and the luminaire should light up. Inspection record books are managed manually.
Self-contained luminaires with automatic test (self-test) onboard continuously display battery and light source circuit status via LED, automatically starting weekly function and annual duration tests. This visual test removes the need to push a test button which often requires a use of a ladder. Inspection record books are managed manually.
Also known as ‘addressable test’, ‘central addressable’, ‘automatic test’, and ‘emergency test and monitoring’ systems
These centrally monitored luminaires feature automatic testing and monitoring capability, notification functions and remote/web access. Inspection record books are automatic/digital.
Relevant standards
EN 62034:2012 Automatic test systems for battery powered emergency escape lighting
How often should emergency lighting be tested?
Manual testing should take place via a monthly “functional” test of short duration to verify if lamps illuminate from the battery source and batteries correctly recharge after the test.
Additionally, a “duration” test is undertaken annually to ensure the lamps illuminate for the full duration time and batteries correctly recharge after the test.
Establishing a testing frequency
Establishing a schedule is important to make sure all tests take place when they should do. A minority of building owners and operators choose manual testing when they prioritise its low initial cost and simplicity over the higher initial investment, but lower lifetime total cost of ownership, of automatic testing alternatives.
If the user performs an annual duration test on all emergency luminaires at the same time, the building cannot be occupied until the batteries are sufficiently recharged.
However, if alternative luminaires are tested, a level of emergency illumination will be provided in the event of a mains failure during the recharge period. In this scenario, the building may be occupied during and immediately after a test.
It is not possible to test alternate luminaires when using a central battery unit. As a duration test needs to be undertaken in full load conditions.
Therefore, in a scenario where the building must be occupied continuously the following options are available:
The automatic option takes management time and hassle out of testing – also facilitating data connection between products to ensure fault-free performance. It follows that more and more building owners and operators are finding automatic testing worth the higher initial investment. It not only reduces labour costs and enables flexible test scheduling, but streamlines testing management processes and simplifies compliance.
