Alarm sensor for a stairwell

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neb

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#284142 2-Apr-2021 23:06

For the Casa de Cowboy's newly-commissioned stairwell, the alarm sensor will be in the unusual position of being in a "room" that's much taller than it is wide, about 2m wide but about 5.5m tall. Mounting it in the standard configuration means that it'll only catch movement at the top of the stairwell, confirmed by some informal testing with a sensor.

The manufacturer's spec sheet shows coverage by area (X axis), not depth (Y axis), so it's not possible to tell how deep the coverage can go. The two options are to either tilt it downwards, or to mount it sideways so the wide-area coverage zone goes down rather than across.

The first one is obviously easier, but without any idea of how good the Y coverage is all that could do is move the dead spot from the bottom of the stairwell to the top of the stairwell. OTOH the sideways-mount option seems a bit... odd. Anyone have an ideas on this?

In case this matters, the sensor is an Optex RXC-DT, dual PIR and MW.

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#2685910 2-Apr-2021 23:11

In the things that make you go hmmmm category:

Note how long ago Google thinks it was posted, then look at the timestamps on the messages...

MadEngineer

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#2685911 2-Apr-2021 23:25

Replace it with a 360 deg ceiling mount?

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neb

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#2685913 2-Apr-2021 23:37

MadEngineer: Replace it with a 360 deg ceiling mount?

Then it would mostly detect the chandelier :-).

On a semi-related note, does anyone have any idea whether the dual-tech sensor I've indicated uses AND or OR for the two techs? AND is for enhanced false positive immunity, which we've never had an issue with, OR is for enhanced detection, but none of the manufacturer's tech info indicates which one they use.

timmmay

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#2685923 3-Apr-2021 06:14

We've had a Bosch alarm and sensors for 5 years or so, we have had maybe 1 or 2 false alarms in that time. I suspect but have no evidence that they require dual things to trigger, movement and IR, rather than just one.

Goosey

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#2685929 3-Apr-2021 08:33

if it’s just a stairwell, why do you need a sensor? Wouldn’t a sensor in the most ‘accessible room for a burglar’ be better e.g. if there’s a room upstairs with a deck say a cat burglar would attempt to use?

And then a sensor outside or near this room facing the main passage?

same for the bottom of the stairs....where do these end up? Normally sensors are mounted above exterior entry points and face inwards to the room....

MadEngineer

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#2686041 3-Apr-2021 13:58

Goosey:

if it’s just a stairwell, why do you need a sensor? Wouldn’t a sensor in the most ‘accessible room for a burglar’ be better e.g. if there’s a room upstairs with a deck say a cat burglar would attempt to use?

And then a sensor outside or near this room facing the main passage?

same for the bottom of the stairs....where do these end up? Normally sensors are mounted above exterior entry points and face inwards to the room....

this.

You're not on Atlantis anymore, Duncan Idaho.

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neb

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#2686184 4-Apr-2021 01:24

Goosey:
if it’s just a stairwell, why do you need a sensor? Wouldn’t a sensor in the most ‘accessible room for a burglar’ be better e.g. if there’s a room upstairs with a deck say a cat burglar would attempt to use?

That's exactly why it needs to be in the stairwell, because that's the one chokepoint in the house that an intruder has to pass through to get from (most of) the points of entry to (most of) the points of interest for burgling.

same for the bottom of the stairs....where do these end up?

In an area with four doors, access to which would require tunnelling through significant portions of the house to get a wire in, and for which opening one or more doors would mask most sensor locations even if you could somehow get an alarm wire down there.

The reason for putting it in the stairwell is that that's by far the most valuable location for a sensor in the entire house.

timmmay

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#2686185 4-Apr-2021 05:41

Could you put one at the top and / or bottom of the stairs?

Goosey

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#2686193 4-Apr-2021 07:25

@neb

Agree, but are you saying all your valuable cash, jewels, electronics are kept in the hallway?

im no burglar, but if I can see a house has an alarm, I’d be making a plan to access the master bedroom for a quick rummage and perhaps leave with a tv, jewels, socks filled with cash, and maybe even some electronics sitting in the bed stands....then leave without tripping the hallway sensor, cause this crook has seen those casa de cowboy photos and thinking there might be some hidden trap door booby traps....

these days, if crooks really want to spend time in your house, they will cut the external sirens, but first cut the copper/fibre to the house....(so the alarm can’t dial out and taking a bet there isn’t a 3G fall over),otherwise it’s unfortunately crooks who want to get something quick to steal so they can then quickly on sell to fund habits and lifestyles.

Ted West and his gang ain’t doing house burgs anymore...

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#2686195 4-Apr-2021 07:28

reed switches on the doors as well

cyril7

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#2686207 4-Apr-2021 08:23

Hi so concider ING the stairs are a key passageway that cannot be avoided, the sensor will only trigger once the burglar gets to the top of the stairs, 5sec later than purhaps you wanted, is that really such a big deal?

Cyril

Edit you could tilt it slightly downwards, but be aware the pickup pattern is already tilted down so it would be a very small amount required.

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neb

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#2686296 4-Apr-2021 12:37

timmmay:
Could you put one at the top and / or bottom of the stairs?

No, see the second part of my reply.

sparkz25

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#2686297 4-Apr-2021 12:50

Install at the top of the stairs in a corner slightly tilted down as @Cyril7 has mentioned would be your best bet.

Do not mount it flat on the wall, as it will not work that well.

neb

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#2686300 4-Apr-2021 12:59

cyril7: Hi so concider ING the stairs are a key passageway that cannot be avoided, the sensor will only trigger once the burglar gets to the top of the stairs, 5sec later than purhaps you wanted, is that really such a big deal?.

It also gets armed at night, and I'd prefer to be warned about an intruder at the bottom of the stairs than right outside the (open) bedroom door. For one thing it'd be firmly closed by the time they got to the top.

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#2686363 4-Apr-2021 18:21

There are high bay PIR sensors which are designed to detect motion in a narrow corridor (some have lenses which can be altered to narrow the field). Unfortunately, I can't find any which are DC powered as they seem to mostly be used for lighting control.

If you must install at the top of the stairs, you could use a photoelectric sensor. If you can get power downstairs, an active IR driveway sensor may be an option. I use one with three sensors across our front yard. It's very forgiving when it comes to alignment so you could possibly get away with mounting it slightly off alignment to cover a wider area.

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