PIR Sensor that can 'see through walls' legal?

[OwainDIYer]

it might be a microwave detector, which can sometimes be activated through walls (more likely through the wooden door). They may be specified for local authority contacts because the sensor can be concealed making them less vulnerable to vandalism than a PIR

http://www.elkay.co.uk/product.asp?id=52&catid=1

Or there might be a loose connection that is affected by vibration.

 

[DetlefSchmitz]

My thinking... Infra-red - wooden door or gap under door.

So experiment with blanket across bottom of door and/or moving across doorway. I know this could be difficult in your situation but maybe you know someone who could assist?

Knowing the mechanism may help in finding a solution.

 

[AnnaBee]

This is a very strange situation. As Kaku says the sensor detects IR disturbance so it has to SEE heat ie not sensing it but seeing it as infra red movement.I would think its impossible for an infra red sensor to see through a solid object.
Its rather like taking a photo through a solid door.
How do you know that its you who sets it off if its behind a solid door. Is it not just coincidence that some thing else has triggered it?
Why don't you get someone to watch while you move towards the door to prove your point.

Because I'm disabled I've got a camera in the spyhole so when the door bell goes I can switch my tv to show me who is there. I left the tv on that and noticed this was happening. I have a screen angled down the hallway so I can see what is happening outside the door as I move towards it. So it is 100% happening because I can see on the screen as I move towards the door that the light outside turns on.

 

[misterhelpful]

Just a thought that entered my head as a possibility after reading that you are disabled; I know you say you don't want to go into details but you wouldn't happen to use a motorised wheelchair or something similar that could be causing some sort of electrical interference, would you?

 

[AnnaBee]

My thinking... Infra-red - wooden door or gap under door.

So experiment with blanket across bottom of door and/or moving across doorway. I know this could be difficult in your situation but maybe you know someone who could assist?

Knowing the mechanism may help in finding a solution.

There is a gap around the door but the whole thing is covered by a door curtain on the inside completely covering the door and frame. The letter box is flush no gaps and has an anti-arson post catcher on the inside. So again no gaps. There is also a big old fashioned homemade draught excluder already blocking any light going in or out from underneath.

I've already experimented with sound. I don't think it is that and I've tried leaving the light inside MY hall on and off. It makes no difference it still detects me when I get to the point in the diagram on page 1 of this thread.

@misterhelpful
No electric wheel chair, nothing electric on me at all when it triggers. Smart thinking though.

 

[333rocky333]

No electric wheel chair, nothing electric on me at all when it triggers. Smart thinking though.

Thats why i asked if other people trigger it,

 

[viewer]

Couple of thoughts: - your answers might give a clue

Your TV camera doesn't use infra red does it?
Although no electric wheelchair; do you use Zimmer frame/ordinary wheelchair?
Do you carry one of those radio alert things?
Do you have a heart monitor - the sort which sends signals to the hospital?
Have you asked someone else to try moving about inside the door?
Do you have a wireless doorbell?
Do you have a loop system of any kind for hearing?
Does it happen whether the door is locked or not?

Whatever the cause, you should contact the council if it is a problem. You don't have to solve it and show them the proof; they'll have a look and maybe just a piece of tape over part of the PIR window is all that's needed.
Best of luck

 

[SimonH2]

it might be a microwave detector, which can sometimes be activated through walls (more likely through the wooden door). They may be specified for local authority contacts because the sensor can be concealed making them less vulnerable to vandalism than a PIR

http://www.elkay.co.uk/product.asp?id=52&catid=1[/QUOTE]
That was my thought when the symptoms were described. Doubt it would work through a wall (except a thin stud wall), but I wouldn't be at all surprised if it worked through a wooden door.

If the council won't fix it, then time to line the door with aluminium foil or paint it with nickel based (conductive) paint I think.

 

[AnnaBee]

Nope just me with nothing electrical at all only my clothes and two walking sticks (wooden) still triggers it. Other people trigger it too.

I tried waving a walking stick and a broom in front of the door while standing back where it can't sense me but it doesn't trigger it. I tried this both in pitch black darkness and with the hall light on. The camera uses no pir sensor it is permanently on unless I manually turn it off.

So either the broom waving around is to narrow for it to notice it or it is reacting to heat movement, yes, no maybe?

 

[AnnaBee]

it might be a microwave detector, which can sometimes be activated through walls (more likely through the wooden door). They may be specified for local authority contacts because the sensor can be concealed making them less vulnerable to vandalism than a PIR

http://www.elkay.co.uk/product.asp?id=52&catid=1[/QUOTE]
That was my thought when the symptoms were described. Doubt it would work through a wall (except a thin stud wall), but I wouldn't be at all surprised if it worked through a wooden door.

If the council won't fix it, then time to line the door with aluminium foil or paint it with nickel based (conductive) paint I think.

So would that not react to the broom being waved around (see post above this one)? That is horrible, I hate the council. Talk about big brother. If that is the problem can they 'turn it down' make it less sensitive?

 

[Mrdjc]

I think it's time to bust out the camera and take some pictures of your hallway and the common area and the device..

 

[echoes]

I'm puzzled. Does that spyhole let through light or does the camera obscure it? Could be that some light from inside is being focussed in the sensor's vicinity, but I'm clutching at straws...

 

[333rocky333]

I think it's time to bust out the camera and take some pictures of your hallway and the common area and the device..

Annabee, this is a public forum so dont post too much information, the light or sensor is all were concerned in

 

[ianblue]

Well Annabee its got me puzzled.
I think I can say with certainty that an infrared sensor cannot see through walls.
Yes microvave can penetrate possibly a timber door but hardly a concrete wall and then pick up your movement on the other side. Microwave is akin to Radar. Although I have been around to long to rule anything out, but I would warn you to expect, scepticism if you go to the council.

 

[AnnaBee]

I'm puzzled. Does that spyhole let through light or does the camera obscure it? Could be that some light from inside is being focussed in the sensor's vicinity, but I'm clutching at straws...

Nope no light is escaping whatsoever. And the camera doesn't trigger it. I leave that on. Only when I move towards it does ít turn on. Anyone got any ideas on why waving a broom behind the door doesn't trigger it but a human does? Would that be consistent with it being a microwave sensor? Also are those things a health risk?

@333rocky333
I agree but the light is just a bog standard 70's Council flat square shade on the wall. And I can't see a sensor.