When installing or replacing alarm and communication equipment, it can be tempting to use whatever suitable-looking cable is already available. However, the type of cable, its length and the environment in which it is installed can all affect how reliably a system performs.
We were recently contacted by a customer who had replaced an older unit with one of our 4G gsm auto dialler products. The dialler was being used as a standalone unit with its own power supply in a bespoke application, but the customer was having difficulty getting it to operate correctly.
After running through the basics, we looked more closely at the installation and discovered that speaker cable had been used over a run of more than 15 metres.
Can You Use Speaker Cable for Alarm Equipment?
Standard copper speaker cable can be suitable for some low-voltage alarm applications, including connections to keypads, door and window sensors and external sounders. These devices use low direct current and carry relatively little power, so unshielded 18-22 gauge speaker cable can work for short, simple runs.
However, there are several limitations to consider.
Speaker cable is rarely shielded, which can leave it more vulnerable to electromagnetic interference (EMI). It shouldn’t be run parallel to high-voltage AC mains cables or close to heavy electrical appliances, as interference could potentially result in system glitches or false alarms.
It’s also generally a two-conductor cable, whereas alarm cables are commonly available with four or six conductors. Finally, standard speaker wire may not have the appropriate fire rating for installation inside walls or certain commercial environments.
23AWG or 24AWG?
For a standard gsm voice dialer, both 23AWG and 24AWG cable can be suitable because audio and trigger signals require relatively little power and bandwidth.
However, there are some important differences.
23AWG has a thicker copper core and lower electrical resistance than 24AWG. This helps minimise voltage and signal drop over longer distances and makes the cable less fragile during installation. It’s particularly useful for longer runs, including those exceeding 50 metres.
24AWG is slightly thinner and more flexible, making it easier to route into tight alarm panels and dialler enclosures. It’s a practical choice for standard shorter installations of up to around 20 metres.
Whichever gauge is selected, cable type and shielding can be more important than the small difference in thickness. Shielded twisted-pair cable is highly recommended where voice dialler signals could be exposed to EMI.
Where Does 22AWG Fit In?
22AWG cable provides another option, offering a useful balance between compactness and electrical reliability over shorter distances.
Its flexibility and relatively low resistance make it suitable for several low-power applications, including telecommunications, telephone frameworks, security and alarm systems, motion sensors, sirens, door contacts and low-voltage LED lighting.
The requirements of the individual installation should always determine the most appropriate cable rather than simply using what’s readily available.
The Right Equipment Needs the Right Installation
Whether you’re installing a modern 4G dialler or replacing an older pstn auto dialer, choosing appropriate cabling is an important part of creating a reliable system. Cable length, conductor requirements, shielding, installation environment and potential sources of interference should all be considered.
At Keystone Electronics, we don’t just supply products and leave customers to work everything out themselves. As this recent example demonstrates, our team can help troubleshoot an installation and identify potential causes when something isn’t performing as expected.
Alongside diallers, we supply a range of equipment for security and connected monitoring applications, including low cost 868 MHz transmitters and receivers.
If you’re unsure which product or cabling arrangement is appropriate for your application, contact Keystone Electronics and our team will be happy to discuss your requirements.