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What Is The Duration That Emergency Lighting Stays On?

When you’re in the middle of an emergency, safety is your main priority. Within commercial or business premises, the main objective is to get everyone out of the building when there is a risk of injury or worse.


Emergency lighting is designed to help you navigate your way out of a building in the event of things like a fire. When this happens, you need the peace of mind that your emergency lighting is going to stay on for long enough to evacuate everyone.

What’s The Need For Emergency Lighting?

The need for emergency lighting is simple; it’s designed to illuminate exit routes throughout a building to ensure that, in the event of an emergency, everyone is able to safely escape as quickly as possible.


Emergency lighting is often installed in places where there isn’t much natural light since it is activated when the mains power fails. You’ll usually find it in windowless rooms, stairwells, lifts, corridor intersections and above exits.

How Long Does Emergency Lighting Stay On?

Emergency lighting is wired to your mains power system but it does not rely on this as the lighting is designed to work when the mains power fails. For this reason, emergency lighting is powered by a backup battery which can be either a central battery or one that’s installed in each unit.

Since the emergency lighting does rely on battery power, this immediately tells us that the lighting will have a cut-off point. In most cases, an emergency lighting system is designed to stay illuminated for up to three hours. However, some systems don’t last as long as this (I’ll talk more about that later on.)

Are There Laws On How Long Emergency Lighting Should Stay On?

It may surprise you to learn that the law doesn’t only state that emergency lighting is required in business and commercial buildings but it also talks about how long the lighting should stay on.


The absolute minimum UK requirement for emergency lighting is one hour although this really only applies when the building can be fully and safely evacuated within this timeframe.


Where buildings are not immediately evacuated in the event of an emergency, it is recommended that the emergency lighting has a longer duration of around three hours.


This is not only important for people trying to get out of the building but is also essential for emergency responders who may need to enter and work in the building while the emergency is still ongoing.

The Importance Of Regular Emergency Lighting Testing

Since emergency lighting is hardly ever used, it can be difficult to tell whether it is functioning as it should. There are some emergency lighting systems, called maintained emergency lighting, which runs all the time.


These systems are connected to the mains and often serve as everyday lighting but, in the event of a power outage, they continue to run as they’ll switch their power consumption over to the backup battery. However, just because they’re illuminated that isn’t to say that they’ll be reliable in an emergency so it’s still vital to test them.


There are three main types of tests that you need to do to ensure your emergency lighting system is working to its best.


  • An annual check by a qualified electrician will ensure that there are no electrical faults with your emergency lighting system. Any issues that are discovered can be quickly addressed.
  • Each month, you should switch off your mains power to check if the emergency lighting activates. There are some systems whose units have a test switch built in so this makes it easier and doesn’t require you to turn off the mains power.
  • Once a year, you should activate your emergency lighting and allow it to run for the full duration. For example, if your system is designed to run for three hours, you’ll need to leave it on for this amount of time. If it turns off before the time is up, this could indicate a problem.

My Emergency Lighting Doesn’t Stay On For Long Enough; What’s The Problem?

Sometimes, you may have an issue with your emergency lighting system and one of the most common is that the lighting does not stay on for the intended duration. This is a problem that should be addressed as a matter of urgency and fortunately, there’s usually a simple solution.


In pretty much every case, emergency lighting systems that don’t stay on for long enough have a faulty backup battery.


As part of the UK regulations on emergency lighting, business owners are required to change the battery at least once every four years. However, in some cases, the battery may fail within this time so you’ll need to contact your electrician for an early replacement.


That said, most emergency lighting batteries have an expected lifespan of up to six years so, in most cases, your battery should last well between replacements.

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