Day/night Sensor Query

[Caravan]

Hi everyone.

I am thinking of installing a standalone night sensor unit to illuminate a light in my porch but I understand from various sources that some work and some don't.  What I would like to know is - When the photocell detects dusk or darkness and switches the light on, does it not then detect the area that is illuminated ie my front garden and think it is daytime and then switch the light off or do photocells of this type only detect natural darkness or daylight?   I have tried to contact the manufacturer to ask this question but their phone line is "Out of Order" and as I wish to instal the unit ASP, I am wondering if one of you kind persons could put my mind at rest.  Any advice would be much appreciated.      

 

[Andy™]

erm... put it above / away from the light?

 

[Caravan]

Many thanks Andy but that did not answer my query ie Do photocells detect light produced from light bulbs or only natural light ?

If anyone knows the answer to this, I'd be gratefull.

 

[Andy™]

light is light, no matter what the source

 

[Caravan]

Once again many thanks for your reply. If what you say is correct then none of the Energy Saving bulbs which have integral day/night sensors ever stand a chance of working as the light bulb is no more than a few inches away from the sensor and I am sure the manufacturers such as Osram who produced them, were aware of this. Also, how do you account for the IP44 type security lanterns which have a dusk to dawn switch off. If what you say is true, they would switch off the minute the floodlight is operated so, to excuse the pun, I am still awaiting an answer.

 

[Andy™]

Once again many thanks for your reply. If what you say is correct then none of the Energy Saving bulbs which have integral day/night sensors ever stand a chance of working as the light bulb is no more than a few inches away from the sensor and I am sure the manufacturers such as Osram who produced them, were aware of this. Also, how do you account for the IP44 type security lanterns which have a dusk to dawn switch off. If what you say is true, they would switch off the minute the floodlight is operated so, to excuse the pun, I am still awaiting an answer.

because the sensor is away from the... forget it. have it your way. you can put the sensor anywhere you like. ideally with the lights its controlling shining directly on it. then feel free to report back here when it doesnt work and admit i was right.

 

[Sidewinder]

You have had the answer, it is down to the location of the sensor, it is totally feasible to do both of the things you say in post #5, with correct sensor location, and what you are asking can also be done, but it needs correct sensor location.

 

[SLIPSHOD & SLAPDASH]

In the case of a CFL with a integral sensor the detector faces away from the light source and is less sensitive than say a photocell on top of a lamppost.  From memory many of the 'all in one lamps' are not for use in fittings. Some  sensors are adjustable  for light levels. 

 

[Marvo]

There's several tricks employed by day/night sensors to prevent them cycling on and off because of the light fitting in the vicinity. Firstly some can tell the difference because they use a very short sample times which helps them determine if the light source has a 50Hz flicker and is therefore not proper daylight. Secondly they can use optical filters to allow through certain part of the real daylight spectrum easier than the spectrum of light frequencies that are more prevalent from electric lamps. Finally there's a differential between the lux required to swith on and switch off. This is how they managed to develope a compact fluorescent lamp (bulb) that has a built-in daylight sensor. Obviously with these the sensor is invariably inseparable from the light so normally they would short-cycle on/off. A lot of it depends on how much you pay for the item. I have a tech doc from Sylvania somewhere on my work PC, if I can find it I'll attach it tomorrow.  

 

[SPECIAL LOCATION]

Hi everyone.

I am thinking of installing a standalone night sensor unit to illuminate a light in my porch but I understand from various sources that some work and some don't.  What I would like to know is - When the photocell detects dusk or darkness and switches the light on, does it not then detect the area that is illuminated ie my front garden and think it is daytime and then switch the light off or do photocells of this type only detect natural darkness or daylight?   I have tried to contact the manufacturer to ask this question but their phone line is "Out of Order" and as I wish to install the unit ASP, I am wondering if one of you kind persons could put my mind at rest.  Any advice would be much appreciated.      

No idea what or who your sources are....

but I do know I have seen quite a few badly installed DIY night sensors...

which may result in people saying they don't work..

BUT as has been said...

Light is light...

Position your sensor correctly and it will operate in the manner you require..

install it wrong and it probably wont....

As an illustration....

Consider water and umbrellas....

If the umbrella is not positioned above the head then it probably wont keep you dry...

But if it is correctly positioned between you and the source of water... 

artificial (hose pipe) or natural (rain)..

it WILL do the job you expect it to do...

PIR's  & Dusk/Dawn sensors correctly positioned will achieve the required objective whatever the source of light..

Guinness

p.s.  Interesting question though!

:Salute

Note to Admins: should this be moved to Q&A's or similar?

rather then "introduce yourself"?

 

[Doc Hudson]

Hi everyone.

Welcome to the forum Caravan, to save cluttering the introductions area with numerous long posts, please put questions into one of the appropriate topic forums, Thank you.

Note to Admins: should this be moved to Q&A's or similar?

rather then "introduce yourself"?

I agree moved.

Doc H.

 

[Caravan]

Many thanks all of you for taking the trouble to reply. I appreciate your input and particularly "Marvo's" explanation and I will go ahead and instal the sensor. My query was simply that I could not understand how a sensor could keep a light on when the surrounding area was bathed in light but Marvo has gone a long way to providing an explanation. Either way, I will post this forum again when it is installed and hopefully working correctly.

Bernie

 

[kerching]

I hve EXACTLY the opposite problem!

£1.5m pound house and they have put a black NEEMA photocell under the eaves (. On a white stucco wall no less!!!)

Outside lights are now on ALL night AND most of the day

I have inherited the job of curing it

Just saying

 

[Sharpend]

Incorporate a timer?

 

[SLIPSHOD & SLAPDASH]

I have found the NEEMA type sensor doesn't like inductive loads so we fit a contactor. The older type you had to fit it pointing in a particular direction but thats been done away with.

 

[Andy™]

I have found the NEEMA type sensor doesn't like inductive loads so we fit a contactor. The older type you had to fit it pointing in a particular direction but thats been done away with.

the one i fitted a few weeks ago still had direction on it

 

[SLIPSHOD & SLAPDASH]

the one i fitted a few weeks ago still had direction on it

Ahh, you Northerners must have the old stock !  I fitted one a few weeks back and it even mentioned it was not directional in the destructions.

 

[Andy™]

possibly

 

[SLIPSHOD & SLAPDASH]

The plot thickens, i have a spare unit on the shelf here so i scanned the instructions



PS, i give up trying to get that the right way up on my pc.

 

[Andy™]

for those not in Oz