Michael Kiddle
Managing Director of Hawkesworth and a nationally recognised leader in electrical and fire safety, Michael (GIFireE) directs one of the UK's leading compliance companies, safeguarding thousands of businesses each year. Through his voluntary Safe Home Initiative, he has identified and removed thousands of dangerous household appliances from vulnerable people's homes, replacing each one with a safe alternative free of charge.
Your emergency lighting system is designed to work when the power goes out. But if the batteries can’t hold a charge, those lights won’t come on when you need them most. Winter power cuts test whether your system actually works.
An emergency lighting discharge test is the only way to verify that backup batteries can sustain illumination for the full required duration during a mains failure.
What Happens During a Discharge Test
There are two types of emergency lighting tests, and understanding the difference between them matters.
A monthly flick test verifies that emergency lights activate during a simulated power failure. It confirms the lights come on, but it tells you nothing about how long the batteries will last under real conditions.
An annual discharge test goes further. It simulates a complete mains failure, running every emergency light on battery power alone for the full rated duration, whether that’s one hour or three hours. If a light cuts out before reaching that time, the battery has degraded and needs replacing.
If a light is rated for three hours, it needs to stay lit for three hours. If it cuts out after two hours, the battery has failed and needs replacing.
This isn’t about whether the light works. It’s about whether it works long enough to keep people safe during an extended power cut or evacuation.
Why Winter Makes This More Critical
Power cuts happen more often in winter. Storms damage overhead lines, heavy snow brings down cables, and increased heating demand can overload local networks.
When the lights go out in an office building at 4pm on a winter afternoon, it’s already dark outside. Without emergency lighting, escape routes become dangerous. Staff can’t see where they’re going, fire exits aren’t visible, and panic becomes a real risk.
If your emergency lighting batteries are degraded, they won’t provide illumination long enough for everyone to evacuate safely. A battery that fails after 45 minutes leaves people in darkness with no safe way out.
This is why BS 5266-1 requires annual full-duration discharge testing. The standard exists because batteries degrade over time and monthly tests don’t catch that deterioration.
How Battery Degradation Affects Emergency Lighting
Emergency lighting batteries are rechargeable. Every time they discharge and recharge, they lose a small amount of capacity. After enough cycles, they can’t hold the charge they need.
Age accelerates this process. A battery installed five years ago won’t perform like a new one, even if it’s been maintained properly.
Temperature matters too. Batteries in cold areas or near heating equipment degrade faster than those in stable conditions. An emergency light mounted near a radiator or in an unheated stairwell will fail sooner than one in a climate-controlled office.
You won’t know any of this from monthly tests. The light comes on, you tick the box, and you assume it works. Then during an actual power cut, it fails after 30 minutes instead of three hours.
Annual discharge testing catches this before it becomes a life safety issue.
What BS 5266-1 Requires for Emergency Lighting Testing
The regulations are specific about testing frequencies.
Monthly functional tests involve briefly activating emergency lights to check they illuminate. This should take a few seconds per light. Results go in your logbook.
Annual full-duration discharge tests require running lights on battery power for their entire rated period. A three-hour system runs for three hours. A one-hour system runs for one hour. This identifies batteries that can’t sustain the required duration.
The discharge test must use key switches to simulate a mains failure, not just unplugging lights or switching off power. Engineers check every emergency light in the building, record the results, and flag any units that fail.
Failed lights need new batteries or complete replacement, depending on the unit type and age.
Testing Commercial Premises Properly
Large buildings can have hundreds of emergency lights across multiple floors. Testing them all properly takes time and planning.
Engineers need access to every area where emergency lighting is installed. That includes stairwells, plant rooms, corridors, offices, and storage areas. If areas are locked or staff-only, someone needs to provide access.
The test runs for hours. A building with three-hour emergency lighting needs three hours of continuous testing. During this time, engineers monitor lights to make sure they stay on for the full period.
This is why many businesses schedule annual discharge tests outside normal working hours. Engineers can work through the building methodically without disturbing daily operations.
Emergency lighting testing services should include a detailed report showing which lights passed, which failed, and what remedial work is needed.
What To Do If Lights Fail the Discharge Test
If emergency lights cut out before completing their rated duration, the batteries need attention.
In many cases, only the battery needs replacing. The light unit itself remains serviceable, and fitting a new battery restores it to full performance.
Older units may not have replaceable batteries, in which case the entire fitting needs replacing. This is particularly common with emergency lights that are more than ten years old.
It’s important to budget for potential replacements when planning your annual discharge test. If testing hasn’t been conducted for several years, you risk emergency lighting failing to work when it’s needed most. Addressing these issues promptly ensures the safety of your premises and keeps your compliance record intact.
Legal Compliance and Duty of Care
Under the Regulatory Reform (Fire Safety) Order 2005 and BS 5266-1, maintaining emergency lighting in efficient working order is a legal requirement.
Monthly tests confirm the lights activate. Annual discharge tests confirm they perform for long enough to be effective during a real emergency.
Your fire safety logbook should record every monthly test and every annual discharge test. Accurate records demonstrate compliance and ensure that nothing is missed between inspection cycles.
Getting Your Emergency Lighting Tested on Schedule
If you haven’t had your annual discharge test recently, it’s time to book it in.
Power cuts can happen at any time, and when they do, your emergency lighting needs to work. Scheduling your discharge test proactively gives you time to identify and replace any failing batteries before they’re needed in a real emergency.
Hawkesworth provides emergency lighting testing for commercial premises across the UK. Our engineers conduct both monthly functional tests and annual full-duration discharge tests in accordance with BS 5266-1.
We work outside normal business hours to minimise disruption, provide detailed reports showing test results, and can arrange battery replacements or unit upgrades for any lights that fail.
Request a quote to arrange your emergency lighting discharge test.
