It's not bugs, dust or humidity.

We have all been there; it's the middle of the night, everyone is asleep and out of nowhere, BEEP BEEP BEEP. The smoke alarms start sounding. Everyone jumps out of bed, the kids are crying, it's panic stations. But wait, there is no smoke, there is no fire. What is going on?

Contrary to popular belief and what other installers might tell you, it's probably NOT bugs, dust or humidity that is causing this horrible problem.

Transient Voltages

If your smoke alarms are hard-wired, then they are directly susceptible to any sort of power quality issue from the grid supply. This can be an undervoltage or an overvoltage condition. In Australia, our normal power supply is usually between 230V - 240V however, this is aloud to fluctuate from 216V - 258V. Many poor-quality smoke alarms simply can not withstand this volatility and can quickly become damaged. When transient voltages occur, the alarms may trigger and start sounding.

Off-peak Ripple Injection

Parts of Australia (including Brisbane) utilise off-peak ripple control, also known as load shedding. This is how the electricity distributor (Energex in Brisbane) can remotely turn on and off certain electrical assets such as street lights, and off-peak electrical tariffs such as pool pumps and storage hot water units. Electrical pulse signals are sent through the entire electrical network at a time that suits Energex and when electricity demand is low - usually at night. Regardless of if you have or do not have a pool or electrical hot water system, everything that is supplied from 240V mains power will receive these signals. Unfortunately this means hard-wired smoke alarms will also receive the ripple injection.

Ripple frequencies can alter the shape of the AC electrical sine wave which can adversely affect DC clock signals utilised by semi-conductors in the smoke alarm and causing it to start sounding. Ripple frequencies if strong enough can also potentially damage the smoke alarm. Consequently, some brands of smoke alarms will state that their hard-wired alarms must only be connected to a ripple free supply.

EMI

Electromagnetic Interference (EMI), is induced electrical "noise" within an electrical circuit which disrupts the normal operation of electrical / electronic equipment. Sources of EMI can be from the natural environment such as the sun and lightning, or from manufactured equipment such as light fittings; this is why smoke alarms must be located a specific distance away from light fittings. Cheap, poor-quality smoke alarms may not be adequately shielded against EMI and therefore may be more susceptible to it, causing them to false alarm.

Radio Frequency Interference

This is a type of EMI. If your smoke alarms use a wireless radio frequency for interconnection, there could be radio interference from other devices. Wireless interconnections on most smoke alarm brands operate within the 433MHz range. This specific radio frequency range is also used by many other household devices such as; baby monitors, wireless game controllers, garage remotes and smart home devices. Due to the airwave congestion of this frequency, it is possible for smoke alarms to receive signals from other devices and begin to alarm.

Capacitive Coupling

This is another type of EMI. If your smoke alarms are hard-wired, they may have a physical interconnection cable between each alarm. The interconnection signal is extra-low DC voltage. If this cable is enclosed with or run parallel too low voltage AC electrical cables in the ceiling, this can cause an induced voltage on the interconnection cable and cause the smoke alarms to sound.

Incorrect Pairing

If your smoke alarms use a wireless radio frequency for interconnection, they may not be paired correctly. When your wireless smoke alarms are installed, the installer should be pairing them all together on their own network with their own code. Incorrect pairing or simply not being paired to each other can cause nuisance alarming; the smoke alarms in your home may detect a signal from sounding smoke alarms in a neighbouring home which will trigger your smoke alarms.

Additionally, Many brands of smoke alarms and other home devices utilise a coding technology limited to 256 codes; not many, considering the multitude of wireless devices in our homes and neighbourhoods. It is entirely likely then, that the code utilised by your smoke alarms is shared with another wireless device.

No Network

Some poor-quality smoke alarms have been known to drop or loose their network connection to other smoke alarms in the home network. This may then cause the smoke alarm to detect signals from other devices or other smoke alarm networks in the area.

Mix and Match

Connecting different brands and types of smoke alarms together can cause nuisance alarming. This is generally seen with hardwired smoke alarms. All manufactures state; to only connect their smoke alarms together and not to mix with other brands. Doing this not only voids warranty, but does not comply with Australian Wiring Regulations as the alarms have not been installed per manufactures instructions. Yet, many installers will do this and comply the property.

Dual Interconnections

This occurs when hardwired smoke alarms all have a wired interconnection with each other AND also have a wireless interconnection with each other. Doing this confuses the whole system and will cause nuisance alarming.

Solar Inverters

Solar inverters used for rooftop solar PV systems can inject harmonics into the power grid. This effect can be compounded through many inverters all switching on at the same time; as is in the morning during sunrise. These harmonics can adversely effect hardwired smoke alarms and cause them to start sounding.

So whilst dust, insects and humidity can absolutely cause your smoke alarms to start sounding, be mindful that there are other factors. The design of the smoke alarm and how it has been installed is critical in how it performs over its lifespan. Don't be fooled by cheap smoke alarms installed by someone who has no idea what they are doing.

Do the job right the first time with River City Smoke Alarms.

Do your smoke alarms randomly sound?

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