What’s the best way to cable an alarm system? The way you run alarm zone loops depends on the nature of the application and your professionalism.
Most installers build their cable plant in the ceiling and drop wires down to their wall-mounted sensors as they go. Other alternatives include running the cable under carpet, under floorboards or around skirting boards. It’s highly likely most installers will favour the technique with which they’re most familiar, but there are always installations that will throw a spanner in the works and get you scratching your head.
A big issue will be whether you can get onto the site during construction and get your wiring into place. There are some big advantages to this and some pitfalls. For a start, it’s going to be a far quicker and easier installation if you’re able to cable up before the walls go in. The only negative is the fact you’ll have to go back a second time and hang your controller, program the system and install sensors.
In many cases though, you’re going to be installing your cable in an existing domestic or commercial premises and that means you’re going to have to go either through the ceiling or under the floors. Installers in NZ and Queensland as well as those who’ve installed systems in older premises will appreciate the fact that it’s sometimes a lot easier to manage the cabling of an installation under the floor of a timber home – this is especially the case in Queensland, where you might need a step ladder to reach the sub-floor.
Cabling At Floor Level
When installing systems in units and commercial premises, you may find you need to stay at floor level. I’m no fan of ground level cable runs. These days if you’ve got a site that can’t be supported by an above ceiling cable plant, I believe you should install quality wireless sensors – especially in commercial environments.
A zone loop that runs around a skirting board is asking for trouble, especially in older systems that may not alarm if power to a zone loop is lost. Even in a more modern system, all you’re going to get is a trouble signal indicating voltage loss. There won’t be any sign that the cable has been cut by foot traffic rather than an intruder, or by a termination fault.
If you need to put in a zone loop in an exposed situation, and sometimes you do need to, hide it under the edge of the carpet, put a slim conduit around it or glue or tack a strip over the cable if you can do so with putting too much stress on the cable. You might also hide the loop in or behind an existing conduit, if it can be done tidily and there’s no AC to create noise issues.
Be certain volumetric detection covers the exposed cable section and be sure to explain any vulnerability to the property owner. It’s good practice to outline deficiencies the site and budget force onto your installation in a commissioning report. One copy of this report needs to go to the client and the other goes into your own files.
Another problem you’ll run into if you cable along skirting boards is crossing doorways. If the floor is polished timber or tiles, then you’re going to have to take the cable over the doorframe where it will be even more exposed to attack or accidental damage. If there’s carpet, you can run under it but take care to tuck the loop into a cable groove or an enlarged crack in the floor.
An alarm zone cable laying directly on a concrete slab will gradually be worn over a period of years, especially if heavy furniture is dragged across it, or high heel shoes step directly onto it. Alarm cable has virtually no protection against physical damage.
Should you be running wiring at ground level or under the floor be sure to install your reed switches down low – you don’t need to cart exposed cable all the way up the door frame to make a top-mounted reed switch just because everybody else installs reeds on the top corner. Discretion is good with reeds.
Pulling Alarm Cable
There’s subtlety required when pulling cable. Sometimes a sticking point will give way with a little extra pressure and other times you’ll only damage the cable if you use too much force. Take care. One thing you should try to avoid doing is hauling an entire light gauge cable through a route from the far end or from the origin of the run.
While this may be easier than shifting the cable in stages the result is likely to be damaged sheathing, stretch and broken strands inside the cable. Pulling a cable into a route using an existing cable run you’re replacing has some obvious advantages and some clear weaknesses. One thing you’re never going to know is at precisely what point a cable snagged, at just what point the exposed wiring could pull on metal studs or bracket edges in ceiling spaces. Behind the walls and under the roofs of most buildings lurks a dreadful mess and navigating it unsighted is never easy to do.
Installation by hand using more than one tech to help the feed is only the way to guarantee a quality cable run. Putting in cables this way will allow you to follow contours more accurately, to protect cable by taping the sheath for additional protection at points with ragged surfaces or corners. You’ll also be able to ensure the cable is running over pipes not underneath them, and you’ll be certain that any mains cabling is nowhere near your cable run. The idea is to ensure cabling is installed in the most secure, direct, economical and reliable way.
We’ve seen some extraordinarily dodgy cable runs over the years, with wires wound around roof beams for support, draped over rafters during builds, and even tucked under the edges of roof tiles instead of held in place using cable fasteners. Take pride in your cabling and it will last decades longer than the alarm system it supports.
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