PIR Sensor that can 'see through walls' legal?

[AnnaBee]

This is the situation. In an enclosed communal area between two council flats there is a light that operates on some kind of sensor (heat/movement, not sure exactly). Now the problem is that it turns on the light when I move near the wall on that side of the flat (within the flat and door closed). There are no windows there. Just a concrete wall and a solid front door.
How is this possible? I thought that these things detected heat or movement, but couldn't 'see' through solid objects. I'd like to go to the loo without a warning light going on outside my front door.

Thanks for reading, any informed input would be great.


Read this bit only if you are bored or annoyed.
P.S. Hello, yes I'm one of those horrid people who sign up and post twenty seconds later. This place came up in a google search so I'm sorry but you seem like you might have some insight into this. Googling hasn't given me many answers. I know it might seem trivial and silly but I am really worried about this please forgive me.

 

[RedHerring2]

Hello and welcome AnnaBee. Don't worry about signing up and asking a question straight away. I'm sure that's how many posters start.

I can't help you with your question, unfortunately, but you really should try in the 'Electrics' Forum. The 'General Discussion' forum is full of opinionated posters.

Ask the mods to move it for you, by clicking on 'Alert Mods' - lower right of the posts.

 

[AnnaBee]

Hello and welcome AnnaBee. Don't worry about signing up and asking a question straight away. I'm sure that's how many posters start.

I can't help you with your question, unfortunately, but you really should try in the 'Electrics' Forum. The 'General Discussion' forum is full of opinionated posters.

Ask the mods to move it for you, by clicking on 'Alert Mods' - lower right of the posts.

Thanks for answering. I did look through to see where was the best place but really wasn't sure where would be considered most appropriate. My google search had brought me too 'Electrics' initially. Then I had a look around & I nearly put it in the CCTV bit. I was hoping general would ruffle the least feathers. I don't mind if they are opinionated so long as I find some answers.

 

[HERTS P&D]

Welcome Anna, can you try and post a picture of the PIR, that way someone on here might recognise what one it is and if they can 'see' through walls.

Andy

 

[EFLImpudence]

You are right about the usual sensors working by detecting heat and movement (infra red).

Just to be sure, do you mean the light in the communal area (outside)
comes on when you walk around your flat (inside)?

I haven't had experience of any sensors which 'work' through walls but have no doubt there are such devices.

I would think that anything like that would have been fitted by the council.
Perhaps you could have a word with them.

 

[Kaku]

Passive is relevant to this

Its not exactly a heat sensor as such
All objects above absolute zero emit infra red
The sensor sees a different level of IR passing across another

An Infra Red heat source, exactly the same level as the background will detect nothing
You are the source,it may be via a glass in the door

Try angling the detector away from the door

 

[AnnaBee]

I'm disabled and without going into details the light being right at the top of the wall near the ceiling means that isn't possible for me to photograph it. All I can see clearly is the big old fashioned square cover over the light itself . I'm sorry that is no help I know.
It only switches on when I am near or in front of the door (me on the inside of the flat inside with the door closed). So it is possibly seeing through just the door not the wall.
It is definitely a council fitted sensor. And yes the light in the communal area and comes on when I move near that corner of the flat. It seems to activate at the point where I've still not reached the front door but if you drew a straight line between me and where the light is on the wall it would pass through the closed door rather than the wall.

Edited to say Just seen the response above. There is no glass in the door. There is a solid wooden door.

Here is a diagram showing me at the point it detects me and the layout.
http://imageshack.us/photo/my-images/31/29472688.png/



Uploaded with ImageShack.us

 

[333rocky333]

a freind of mine has a porch lantern that comes on when you are on the upstairs landing, and was fitted by the council, it baffles me as the sensor is aimed away, in our case though i think it deflects back of the car windows or something and shines back through the upstairs window, is the outside wall opposite painted with a glossy finish.

 

[AnnaBee]

a freind of mine has a porch lantern that comes on when you are on the upstairs landing, and was fitted by the council, it baffles me as the sensor is aimed away, in our case though i think it deflects back of the car windows or something and shines back through the upstairs window, is the outside wall opposite painted with a glossy finish.

No the wall isn't painted glossy in the communal area. It is reacting to movement within my flat either through a solid concrete wall (NO windows) or the solid wood door(NO windows) with a heavy thick door curtain hung on the inside of the door. So no light can escape from my flat out. And it happens regardless of whether the light inside my flat is on or off. It reacts to me moving inside the flat with door shut.

 

[333rocky333]

Could the council have put a sensor internal to your property for your conveniance and not made you aware, apart from a gap round the door or the letter box or maybe a door spy hole, i give in,
do other people trigger it or is it just you.

 

[Blasphemous]

If this light is causing a nuisance to you and/or someone else then I suggest the first line of attack in getting it sorted is to contact the local council and inform them of the nuisance their equipment is causing to you.

Also, is this a new problem or something that has gone on for a while? Give them the full details.

 

[RF Lighting]

The only thing I can think is that the fitting is sound activated rather than by PIR.

These are sometimes installed in offices where people are sat still at a desk, but the lights are required to stay on.

 

[Equaliser]

http://www.xandem.com/technology-that-can-see-through-walls-goes-commercial

Our cousins over in salt Lake City, USA, are already enjoying this technology.

Looks too expensive to be used by Local Council, but it could be a trial run as it appears to be a new product on the market.

 

[AnnaBee]

Could the council have put a sensor internal to your property for your conveniance and not made you aware, apart from a gap round the door or the letter box or maybe a door spy hole, i give in,
do other people trigger it or is it just you.

No that isn't possible, I've lived here for years. Short of them breaking into my flat in the night and fitting it while I slept. And I have chains on the door and I'm home 24/7. I have not left the flat since I moved in.
The light was on 24/7 at first then they fitted a sensor this year so it would turn on only when someone entered the communal area.
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.

Could it be detecting heat through the gaps? Because it definitely can't be light from my flat triggering it because none can escape.

@Blasphemous
I want to be armed with the facts so I can get them to change it. I find it intrusive that my movement in the flat triggers a light outside it. I don't want them fobbing me off. So I want to be clear on why it is happening first before I approach them. Plus the whole point was energy conservation. That is patently failing as it goes off every time i go down my hall to the bathroom.

 

[ianblue]

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.