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Power Supply Units

Fire alarm power supply units are necessary for ancillary fire alarm systems. Business and public premises are required to have fire alarm systems in place, in line with the Fire Safety Order 2005. Due to their high voltage, they need to be powered by the mains. This is where the power supply unit (PSU) comes in. 

Most power supply units also have a battery backup. This ensures the fire alarm system is still fully functional in the case of a power outage.

We have a wide range of fire alarm power supply units to ensure your system runs reliably and with little maintenance. Whether you need a full 24-volt main supply unit, door release supply unit or fire alarm panel mains isolator, we've got you covered. 

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What are fire alarm power supply units?

Power supply units (PSUs) for fire alarms are connected to the main power of the building. They ensure the fire alarm system runs 24 hours a day, keeping the building and its occupants safe at all times. As most fire alarm units have a high voltage, they require mains power to operate. 

There are also many other devices that require their own power supply unit. These include beam detectors, AOV systems, aspirating smoke detectors, sounder systems, and auto-dial communicators. Additionally, magnetic fire door holders require a smaller PSU. Each is individually powered, enabling them to communicate with the fire alarm system. 

What are the fire alarm power supply requirements?

Fire alarm supply units should have two independent power sources to ensure there is a backup, should the main power source fail. These are usually mains power as the primary source, and batteries as the secondary source. Up-to-date fire alarm systems should be 24 volts with backup batteries of the sealed lead-acid variety. 

Larger fire alarm systems often have their backup batteries housed separately from the control panel. In this case, they should be located as close as possible to the main system. And no further than 10 metres away.

What is the best fire alarm supply unit battery?

Power supply units (PSUs) usually use 12-volt lead-acid batteries. 24-volt fire alarm systems will require two 12-volt batteries to operate.

There are many different battery manufacturers, however, we recommend Yuasa rechargeable batteries for fire alarm supply units. Yuasa is known for its reliability and low maintenance, with a life span of up to five years. Their advanced electrolyte suspension system technology means the batteries can be used in any orientation, without leaking or building up gases.

What is a fire alarm key switch?

A fire alarm key switch in the UK is a device that allows the Mains supply to a fire alarm panel to be switched on or off. It is typically a red box that is located near the entrance to a building or exit stairwell. Fire alarm key switches are an important safety feature in many buildings in the UK, as they provide a way to quickly and easily activate the fire alarm system in the event of a fire. They are also useful for testing the fire alarm system on a regular basis.


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