Industrial lighting

[Steve]

I was in B&Q yesterday, a store they built in Doncaster about 2-3 years ago, a good 3-minute walk from one end to the other. It has skylights and 3-tube fluorescent fixtures for lighting. I noticed the natural light got a bit dimmer, possibly the sun going behind a cloud. Then, the most amazing thing happened. The fluorescent lights got BRIGHTER!

I appreciate that this is probably part of an overall building environmental system, which manages heating / lighting in order to save energy, but can someone elighten me as to how it is possible to dim tens of kilowatts of fluorescent lighting, in unison, according to the brightness of the natural light? Just curious.

(They installed a similar system in some road tunnels in Doncaster centre 2 years ago, supposed to be constant fluorescent lights, with additional sodium lights coming on when its brighter outside. At the brightest setting, the ceiling is lined at both sides by lights! However, the sodium lights haven't made an appearance recently. Its either all or nothing. Usually drive through at night, and all the lights are on, blinding everyone, and during the day when just the florries are on and i cant see nothing. Waste of money.)

 

[ricicle]

Dimmable fluorescents controlled by local triac controls for small banks in turn controlled by one LDR controller monitoring external light levels ?

 

[DESL]

Or even an optical illusion

As the natural light fades so your iris opens and makes the artificial lighting appear brighter - just a thought.

 

[Lectrician]

So what does the photocell on top of traffic lights do then?? Brighten the lights when??

Not a trick question, but one that most people get wrong!

 

[Steve]

So what does the photocell on top of traffic lights do then?? Brighten the lights when??

Not a trick question, but one that most people get wrong!

I would say in the bright sunlight it brightens the lights, but i'd guess i'm wrong?

no idea then, but they installed some new LED traffic lights on my route to/from work, and they are blinding in the dark.

 

[DESL]

So what does the photocell on top of traffic lights do then?? Brighten the lights when??

OK bait taken - dims the lights at night.

 

[breezer]

Yes it does dim traffic lights at night.
mostly so the glare doesnt dazzle drivers, but also it saves power

 

[Pensdown]

I appreciate that this is probably part of an overall building environmental system, which manages heating / lighting in order to save energy, but can someone elighten me as to how it is possible to dim tens of kilowatts of fluorescent lighting, in unison, according to the brightness of the natural light? Just curious.

I'm not sure what dimming traffic lights have to do with the OP

To answer your question, the ballast's in dimming florys have a 0-10volt DC control input so its a bit like switching a large load through a contactor.

The 0-10volt control signal can come straight from a 0-10volt photocell but more often than not on large projects it comes from a central controller and the photocell is just one of the control inputs.

The 0-10volt signal loops to all the ballasts in one group in twisted pair cable and bobs your uncle they all control to the same light level. You can programme time delays, ramp up & down speed and a host of other features.

In large supermarkets & sheds the lighting is closely controlled but not for energy conservation reasons. As you probably already know, it's designed to make you spend money

 

[Steve]

Cheers Pensdown. Good explanation. I take it you have been involved in such a project?

And re. supermarkets, Our local morrisons recently had a bit of a re-jig. They ended up fitting new spotlights (some kind of induction lamp) in the ceiling above where the toiletries are (makeup, etc), I guess to brighten up the aisles, and make it feel cleaner. In fact, most of the aisles have had additional ligting fitted over the years (opened about 1994, IIRC). There used to be just the rows of ceiling lights, but now most aisles have additional high-output fluorescent rows suspended low, directed at the shelves.

However, the company I work for has said they are aiming for lower light levels in their newer stores and refurbishments, to save energy. I think a figure of 25% reduction in light levels was mentioned. I think this makes sense because many of our stores open till 11, and we get people coming in at night complaining its too bright.

Some of our newer stores have olde-worlde LF fluorescents, in order that they can fit special starters which modulate the flickering of the lights to communicate data to electronic shelf edge price displays. All the starters are linked with data cable, and linked to the store's price database, the lights refresh the data to every SEL in the store every 5 minutes. Very clever stuff. The lights are contactor controlled too, so at about midnight when the store computer recieves updates, increases and decreases every day, it switches all the lights on until it has cycled twice through all the updates to the SELs.

 

[securespark]

[Old Git="securespark"]Eeeh, and to think that when I started in retail, barcodes (and sell-by's for that matter) were very much in their infancy...[/Old Git]

 

[ppuch1]

This thread should have been named Commercial lighting, but that's just being pedantic.
What has been explained on this thread is something that a lot of big high street stores do. Its all about giving the correct 'Colour' of light to display their products. Just check it out next time you are at a Sainsburys or Boots. They often have warmer colour lamps over the meat counters to give it a 'warm' look and make it more inviting to buy the product. If you use very bright lights i.e. 8400K (cool white) then it can give a feeling of being cold. whereas an 8300K (warm white) renders a warmer one. Standard colour being 3500K
This may be difficult to see at first but if you were to put these coloured lamps next to each other you would instantly see the difference it makes.
K is for Kelvin and denotes the colour temperature. This colour rendition mainly applies to fluorescent lamps.

As far as the lights dimming when it clouds over, this has been mentioned by Ricicle as "LDR controller monitoring external light levels"
This means that they do save power but more importantly, you stay in the store and buy their stuff!

 

[Steve]

They often have warmer colour lamps over the meat counters to give it a 'warm' look and make it more inviting to buy the product. If you use very bright lights i.e. 8400K (cool white) then it can give a feeling of being cold. whereas an 8300K (warm white) renders a warmer one. Standard colour being 3500K

Very true. I recently called out a contractor to change about a quarter of the tubes in the shop (it had been neglected, looked terrible, only I noticed though ). The guy ran out of tubes, and had to put a couple of "pink/cream" tubes in, normally used in meat displays. Still left a couple without tubes. The rest are bright white. I was under the impression these pink/cream tubes dont have such a bad affect on the life of the meat due to the different spectrum of light. Personally, I think they look naff anyway, even in a meat fridge - look along a row of fridges with a meat fridge halfway down and a different colour tube, it looks silly.

 

[breezer]

its nothing to do with affecting the meat, its the colour temperature.

If meat is lit by a white / blue tube it looks "sick"

If meat is lit by a white / pink tube it looks "healthy"

 

[Pensdown]

I take it you have been involved in such a project?

The only daylight dimming projects I get involved with are in offices but if your store in Sheffield needs a competitive quotation......