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How to fit a dummy alarm box

Updated: 20.10.2026

The box is on the kitchen table, and the question is where a plastic decoy belongs on a UK house. Fit it where a passer-by can see it, and where you can still open the cover next year. A dummy under the eaves has failed the only job it has. This is how to fit a dummy alarm box as a screw-fixed sign, not a wired alarm. Product choice stays on the [dummy alarm system comparison](/hub/burglar-protection/dummy-alarm-system). Notes were checked on 19 October 2026. This is not a lab test. A qualifying purchase can earn us a commission at no extra cost to you.

The box is on the kitchen table, and the question is where a plastic decoy belongs on a UK house. Fit it where a passer-by can see it, and where you can still open the cover next year.

Our top picks

Yale Yale AC-DBX dummy siren

Best overall

Yale Yale AC-DBX dummy siren
9.1/10about £22.03
View offer
Nedis Nedis DUMSS20WT dummy siren

Alternative

Nedis Nedis DUMSS20WT dummy siren
8.6/10about £22.74
View offer
QUANAN QUANAN blue dummy alarm box

Best value

QUANAN QUANAN blue dummy alarm box
8.2/10about £19.99
View offer
On this page
  1. 1.Pick a spot you can see and reach again
  2. 2.Screw it flat to a sound wall
  3. 3.Set the light, then close the cover
  4. 4.When to stop and get help

Pick a spot you can see and reach again

Stand on the pavement. The useful place is a flat wall a passer-by notices, level with the window heads, not in the eaves. Leave room for the lid to come off, or you cannot change the cells. Height is opinion, not a legal figure. On a MyBuilder thread one fitter suggests about 2.5 to 3 metres on the front face, not on a chimney, a low roof, or a window frame. Another prefers the box low and obvious. Do not treat 3 metres as a requirement. A real-sounder manual asks for screws into brick rather than mortar. Use that mounting point only. Do not copy cable or tamper steps onto a silent box. One box on the front is the pattern, including a ground-floor wall you can work safely.

Screw it flat to a sound wall

Use the pack's screws, not foam pads. A pad can let the box tilt. The Yale, the Nedis, and the blue box include fixings. The SD listings do not. Yale allows the house and an outbuilding. That is still a wall mount. Drill into the brick, not the mortar, and sit the back flat. The Yale is about 500 g, the Nedis about 510 g, the blue box about 600 g, and the Maclean about 310 g. If the render is loose, or you are looking at tiles, stop. Check the cell count on the dummy alarm system buying guide before you commit to the holes.
Yale Yale AC-DBX dummy siren

Testsieger

Yale Yale AC-DBX dummy siren
9.1/10about £22.03
View offer

Set the light, then close the cover

A UK review of the Yale says to switch the LED on before you shut the cover. Do that on the ground, and photograph the holder. Reviews of the Maclean report one LED and three cells against bullets that say three LEDs and four AA. On the blue box, a review says the instructions mention four cells and the holder takes three. Do not silicone every edge. A blue-box review described sealing the top and sides after water got in, and a sealed lid can hold a puddle on the cells. If the listing states IPX5 or IP44, rely on the housing as supplied. A dead light is often flat cells, which is on the solar or battery dummy alarm page.

When to stop and get help

Stop if the height is more than a gutter ladder you can manage, if the wall is tile, or if the power idea is a mains adaptor. These boxes are battery housings, or a solar top over small cells. They are not a circuit. A torch-charger note is dissatisfaction, not a method. UK mains are 230 V. Call someone for the ladder. Call an alarm installer when you need a sounder or a certificate. The best dummy alarm system page only matches a silent housing to a job. Two boxes do not meet a police note written for active sounders. Fit one visible box and leave the cover serviceable.

Common questions

How high should a dummy bell box go?
There is no British Standard height for a decoy in the sources used here. Fitters on a MyBuilder thread suggest a low, obvious spot or about 2.5 to 3 metres on the front face. Treat that as opinion. You should still see it from the street and remove the cover when the cells need changing.
Front wall, side wall, or under the eaves?
Use the front elevation, on a flat wall with room to open the lid. A side wall can work if it faces the path people use. Under the eaves the lid will not come off, and the box disappears into the shadow. Shelter is not the same as burying the housing in the soffit.
Do I need a professional installer for a plastic decoy?
Not for a single screw-fixed box on a wall you can work safely. You need help if the height, the ladder, or the substrate is beyond you, and an alarm installer if the job has become a sounding system. A dummy does not take NSI or SSAIB paperwork. Do not hire an electrician to feed it from the mains.
Can I stick a dummy siren on with pads?
Use the screws and plugs when the listing includes them. Pads are a poor substitute on brick or a wet wall, because the box can tilt or fall. The Yale, Nedis, and blue box include fixings. The SD listings do not state any.
When do I turn the LED on?
Before you close the cover and before you climb. A UK review of the Yale says to switch the LED on first. Confirm a flash at ground level, photograph the holder, then mount. The SD decagon has no light, so there is no switch to set.
Should I fit two boxes because the police guide says front and rear?
No. Those notes are about audible boxes on a working system. A dummy is one sign. A second shell still does not detect or sound. One visible decoy, with the cover reachable, is the fitting pattern here.

Related pages

Dummy alarm system

Best dummy alarm box: match the housing to the job

Dummy alarm box buying guide: six checks on the listing

Solar dummy alarm box or a battery housing in the UK

Dummy alarm vs real alarm: what an insurer will accept

Sources

Public UK sources from the research digest. Listing prices, stars, and review counts are from amazon.co.uk on 19 October 2026.

  1. Yale AC-DBX dummy siren (retrieved 19 October 2026)
  2. Consumer Rights Act 2015, section 11 (retrieved 19 October 2026)
  3. NSI on PD 6662:2017 for intruder and hold-up alarms (retrieved 19 October 2026)
  4. NSI, intruder alarm systems (retrieved 19 October 2026)
  5. Redditch Borough Council home security guide, August 2021 (retrieved 19 October 2026)
  6. CSA Group, ingress protection (IP) testing (retrieved 19 October 2026)
  7. MoneySuperMarket, burglar alarms and home insurance (retrieved 19 October 2026)
  8. Aviva, which alarm system for your home (retrieved 19 October 2026)