OTish Hand driers & Hi Viz?

[The Medway Handyman]

Had to change a toilet seat this afternoon, office block, single WC room about 6' x 8'.

It being a trifle inclement outside I was wearing a Hi Viz fleece, bright yellow, reflective strips.

As soon as I entered the room the automatic warm air drier started up & stayed on.

If I left the room it switched off & stayed off.

After about 10 mins the room became rather warm, so I took the fleece off & left it outside the room. Drier didn't come on unless you put your hands underneath. Weird.

Spent a few mins waving the fleece in & out of the room like a demented matador. Not underneath the drier where the sensor is, but in front of it.

Something about the hi viz was definitely triggering the sensor on the hand drier. But what?

[ARWadsworth]

There is a well known fault/problem (but not admitted by the manufaurer but well known by electricians) of some hand driers activating when the PIR lighting in the toilets are activated (or just by turning the lights on).

BTW was it a Dyson hand dryer?

[Brian Gaff]

Well who knows, maybe its sensitive to one of the wavelengths of light that the day glo stuff converts the light to. Seems odd though as i'd have thought the sensor was not light based. Brian

[dennis]

Well I doubt they are passive IR, the stream of hot air would keep them triggered. They are almost certainly working by the light from a led(IR?) being reflected back to a receiver.

[Andrew Gabriel]

The scotchbrite reflective strips on them are very reflective to infra-red, as anyone who's seen them in a night vision camera will have found. It will be reflecting some IR source which is normally out of sight of the hand drier into its sensor.

[Andy Burns]

Occupancy sensor for lights or cistern?

[fred]

In article , Andrew Gabriel writes

The key feature being that they reflect back in the same axis as the light is received so a stray reflection from a source/detector combo[1] will be bounced back direct to the receiver (via the same stray reflection path), triggering it.

I imagine the receiver will be set quite sensitive as it is normally receives reflections from (non reflective) hands.

Normally, stray reflections from shiny bathroom surfaces will not affect the detector as they will bounce around randomly and don't reflect back directly at the source/detector.

[1] Short wave IR, it can't use a PIR as the hot air would retrigger it.

[Halmyre]

Not sensitive enough in some cases where I'm waving my hands about like a demented signer for the deaf, trying to get the blasted thing to switch on.

-- Halmyre

[Owain]

I have invisible hands too, which is why I end up doing Nazi salutes to the PIR on the staircase lights.

Owain

[Newshound]

Try wearing hi-viz gloves, then you will *really* start getting funny looks :-)

[Bob Eager]

So that you can see where you're going when you have to get up in the night? .-)

[Owain]

So I can move feet quickly from bed to slippers without treading on wire clippings, solder snots, screws, and anything else littering the bedroom carpet.

Owain

[Huge]

What's wrong with nightlights? We have a number of Osram Lunneta (sp?) which are very good.

[Andrew Gabriel]

Reminds me of my bedroom floor as a teenager. I did once step on an upturned DIL IC, which plugged itself into the bottom of my foot, resulting in 2 rows of red dots when I extracted it. Fortunately it was only an 8-pin DIL, and not a 40-pin one ;-)

[Huge]

A rather superior version of stepping on a Lego brick.

[Bob Eager]

Or a wire wrap socket.

[Bob Eager]

But if you're wandering to the bathroom or kitchen...

[Huge]

We have one in the bathroom.

[Bob Eager]

We've found that the little green lights on the smoke alarms on the landing provide a surprising amount of light. And there's a streetlamp at the back of the house that lights the bathroom sufficiently.

[Huge]

Ah, yes. Streetlamps. The nearest one is over a mile away.