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Cost of Installing Hardwired Smoke Alarm

A guide to installing smoke alarms that are hardwired in, including the cost, and what the job might entail.

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If you’re thinking of installing hardwired smoke alarms in your home or business you’ll find everything you need to know in this article. We’ll look at the most common methods of installing these devices, the cost involved, as well as considering potential problems a when carrying out such an installation.

Cost involved with installing a hardwired smoke alarm

This will depend on how many smoke alarms you are fitting, but as a guide, you are likely to pay around £20 for a mains smoke alarm, and between £50 and £80 for a professional electrician to wire it into your mains system. The unit cost is always likely to be multiples of the purchase cost, but the cost to install will not raise at the same rate, so it becomes more cost-effective to fit more units.

What are hardwired smoke alarms?

The term ‘hardwired’ means that an electrical cable taken from the buildings electrical system runs straight into an electrical device. The device doesn’t plug into an electrical receptacle, so cannot be disconnected by accident.

From the exterior, hardwired smoke alarms look similar to their battery-powered equivalents and are positioned in similar areas within the home. The variance is that an electrical cable runs hidden behind a ceiling or wall, directly to the smoke detector. The electrical cable delivers power to the smoke detector at all times, excluding the occurrence of a power failure. Should the power fail, the on-board battery resumes power to the smoke detector until the mains power is reinstated.

What installing a hardwire smoke alarm entails

The fitting of smoke detectors always make sense and for a decent reason: Research proves that smoke alarms save lives and assets by warning inhabitants to both early and smouldering fires. Fires often start so quietly that occupants have no idea that their property is on fire until it is too late. Smoke detectors stay active all day and all night, continually sensing even the faintest evidence of smoke and fire and alerting occupants to the possibility of danger at the earliest opportunity.

Smoke detectors work when they have a continuous electrical charge. This is supplied by robust batteries in many cheaper situations, and these make sense to fit. Still, when batteries die, smoke detectors become useless, and that can be very dangerous, particularly if the occupier believes the sensors to be still operating correctly. Many studies have shown that dead batteries caused about 25% of all failed smoke detectors, but hardwired devices prevent this from happening by always having a charge supplied to them.

At least two alarms should be installed inside a house – one optical and one ionisation, and if possible they should be interconnected. At least one alarm should be installed per floor of the building so in a house with two floors. For the utmost protection, a detector should be fitted into every room apart from the kitchen, bathroom and garage because they’re expected to encounter greater than average amounts of smoke. A mix of optical and ionisation alarms spread around the property is recommended.

Before fitting smoke alarms, the power to the property should be shut off at the isolators, and this will need to be carried out by your electrician. Fitting mains smoke alarms usually entails seating the fitting receptacle onto the ceiling and having your electrician taking a spur line off from a local, convenient source that cannot be switched off. Your electrician should be able to advise you as to how it is best to fit such alarms and will deal with the necessities of the wiring.

Your electrician will terminate the mains wiring with an electrical connector that corresponds with the mains input connector on your smoke alarm. This type of connection means that new units can be put in place as required with ease, requiring only the delatching of the detector from its baseplate, and disconnection of the connector to remove the old unit, and with reconnection of the new unit being the reverse.

Once your baseplate is attached to the ceiling, the electrical connector can be fitted to the appropriate point on the actual detector. Then the whole unit latched onto the base plate to attach it to the ceiling. Hardwired smoke detectors can be ‘chained’ together with a conventional mains electrical supply, but it is best to have some different mains sources so that one mains outrage doesn’t knock out all of the alarms.

Other jobs to tackle

The fitting of hardwired smoke alarms will involve analysis of your home or office electrical wiring it becomes an ideal opportunity to assess the state of your wiring and have a qualified electrician fix any problems that may exist.

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Sam J

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