Smoke and Carbon Monoxide Alarms

Smoke and Carbon Monoxide Alarms

07/02/18 Posted By:Admin

Smoke alarms provide a vital early warning and can allow extra time for you and your family to escape if there is a fire in your home.

Since October 2015, landlords are legally required to install smoke alarms in rental properties and could face fines of up to £5,000 if they fail to comply.

There are many different types of smoke alarms available including strobe light and vibrating-pad alarms for those who are deaf or hard of hearing, joint smoke and carbon monoxide alarms, and mains-powered alarms.

We recommend fitting smoke alarms that come with a 10 year long-lasting sealed battery.

Mayo Electrical Contractors have come up with some important tips to making sure your smoke alarms are working properly:

1. If you have a hard-wired smoke alarm, make sure it is installed by a qualified NICEIC electrician.

2. Always test your alarms on a monthly basis to make sure they are working properly. Most alarms will have a special button to make this process simple and quick.

3. Replace the batteries in your smoke alarm as soon as you hear the low-battery warning sound. Batteries should be replaced once a year regardless of whether they run low.

4. Get your smoke alarm tested by a certified electrical engineer.

5. Consider installing a heat sensor alarm in your kitchen rather than a smoke alarm. This will prevent the alarm from going off due to cooking fumes.

6. Interlink all your alarms so they all react the same to a fire. Electrical engineers can install a fire alarm system so all parts of the house go off at the same time, and so all alarms sound the same. You may want to consider installing additional warning signs such as a voice announcement or flashing lights for people with hearing or sight impairment

7. Make sure everyone in the house knows what your fire alarm sounds like and what measures they should take as soon as they hear an alarm. You may want to consider regular fire drills so people can practice exiting the building.

8. Even when you have your smoke alarm tested on a regular basis, they should be replaced every ten years.

9. Your fire alarm system should comply with the BS5839 safety codes for detection, installation, and maintenance.

10. Because smoke rises, install smoke detectors high on a wall or ceiling.


Sometimes called smoke detectors, you need multiple, linked smoke alarms for your property to be properly covered.

For example, if a smoke alarm is only fitted in the hallway, should a fire start in the bedroom the occupant's life may already be at risk before the alarm would activate.

You should fit smoke alarms in every room

As a minimum you should have at least one device fitted on the ceiling of every floor in your home, however, we recommend you fit one in every room you regularly use as well as in the hallway.

Ideal locations for smoke alarms include rooms where electrical equipment is left switched on, such as living rooms or bedrooms.

As well as fitting smoke alarms in your home, you should also fit a heat detector. These are designed for use in the kitchen and go off when a certain temperature is reached.

Do not place smoke alarms in kitchens or bathrooms as the steam can damage the unit or unintentionally activate it. You should also avoid fitting the devices on walls as this could result in a delay in the alarm activating because of the smoke needing to travel along the ceiling and down the walls.

Always read the instructions that come with the alarm for further fitting information.

  • Do not try to replace the battery on a 10 year long-lasting smoke alarm. Dispose of the device and replace it.
  • Never disconnect or take the batteries out of your alarms.
  • If your smoke alarms beep on a regular basis, change the battery immediately.

Smoke detectors are capable of saving lives by giving an early cautionary signal to a looming fire hazard. There are basically two main types of smoke detectors:

  • Ionisation Detectors
  • Photoelectric detectors


Ionisation Detectors

This type of smoke detector has an ionisation chamber which is exposed to air. The ionisation chamber has a couple of plates across which voltage is applied through a battery. A source of ionising radiation assists in detecting the smoke.
A chemical element, an isotope of americium-241, is placed inside the chamber which continuously decays to generate alpha particles. The alpha particles ionise the air present inside the chamber. The electrons knocked off by the alpha particles are attracted by the positive terminal of the battery and a small electric current is produced. The smoke detector remains silent until the current keeps flowing. However, if the smoke enters the chamber, the particles tend to neutralise the charged ions. As soon as the detector senses that there has been a drop in the current flowing through the circuit, an alarm is set off.

Photoelectric Detectors

The photoelectric or the optical photo detectors are the most commonly fitted smoke detectors in public premises. The smoke detector has a light source, typically an LED, and a sensor placed inside a chamber. Both of these are situated at right angles to each other. This is known as T-shaped construction where the light source is fixed at the bottom of T.
This specific design does not allow the alarm to go off in normal circumstances because the light will not be able to reach the sensor as it passes straight up, uninterrupted. However, in the presence of smoke, the particles will rise up and eventually enter the detector. Since

smoke particles are heavy, they will scatter the light and make it fall upon the sensor, which will then generate a current, sounding a loud enough alarm to wake you up.


Which is better – Ionisation or Photoelectric?

The ionisation detectors are cheaper but they require proper disposal because of the radioactive isotope, as it can cause harm if inhaled directly. They are also extremely sensitive and may cause the alarm to sound upon very little smoke, thereby, being prone to triggering false alarms.

It is equally important to get your smoke detection system checked regularly. A faulty system is worse as it keeps you under the impression that you are safe even when you are not

Carbon monoxide (CO) poisoning can kill. Although you cannot see, taste or smell the gas, symptoms of carbon monoxide poisoning include:

  • Headaches
  • Dizziness
  • Nausea
  • Tiredness
  • Confusion
  • Breathlessness
  • Stomach pain
  • Collapse
  • A loss of consciousness

If you suspect carbon monoxide poisoning or if your CO alarm sounds get some fresh air immediately. Open doors and windows, if possible, and leave the building. You should seek medical attention immediately and explain your symptoms may be related to carbon monoxide poisoning.

If you suspect there is a carbon monoxide leak in your building, call the National Gas Emergency Service on 0800 111 999.

Where does carbon monoxide come from?

Install a carbon monoxide alarm

If you live in a property that has gas appliances such as cookers, heaters and gas fires or solid fuel-burning appliances, such as a wood burner or coal fire, you should install a carbon monoxide alarm.
Carbon monoxide alarms should be placed in the rooms where the fuel-burning appliance is e.g. the kitchen or lounge.

These alarms are different to smoke alarms. A standard smoke alarm will not detect carbon monoxide, however, you can buy dual smoke and carbon monoxide alarms

When buying a carbon monoxide alarm ensure it meets current British or European safety standards and carries the appropriate safety mark - EN 50291 and CE - on the product and packaging.