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  1. #1
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    Feb 2006
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    Default Some actual shed illuminance measurements.

    There have been a number of postings regarding shed lighting recently but all of these are based on manufacturers specs for their lighting fixtures. What really matters is the actual light that gets onto a surface. This can differ markedly from theoretical values for a variety of reasons such as the age of light appliances, positions of blockers including operators, reflectors and absorbers, windows, etc.

    I was visiting my former work colleagues this morning and managed to borrow a Lux Meter and have just used it to measure the actual illuminance (in lux or lumens/m^2) at various positions around my shed.
    Two numbers are shown for each shed position. The height at which these measurements were taken were where the workpieces would normally be located, eg on a bench or in a lathe chucks etc.

    The first number is with no artificial lighting, just the natural light available at midday. These numbers are quite low because today is a very cloudy and gloomy day and shed has small windows.
    The second number shown at each position is with all 21 LED fluoro tube replacements available in the shed on. The theoretical or nominal illuminance inside the shed is thus about 1000 lux - however, the LED tubes are not spaced evenly throughout the shed.
    In the cases of the DP, Metal Working Mill (MWM) and TS, these machines also have LED spotlights (SL) that that light up the key area of action on these machines.

    With no lights on, the natural lighting ranges from a paltry 2 to a high of 316 lux.
    The "2" lux low is under the DP which is well away from any windows on a dark side of the shed.
    The 316 lux value on bench 2 is under a large skylight so one would expect that position to be higher that the rest of the shed.
    The other high ambient light value is he 154 lux at Bench 3 (marked as bench 2 near RHS Window on diagram) which is under a window that is partially covered by a Bouganvillea
    Screen Shot 2019-05-16 at 12.00.11 pm.png

    When all the lights are on, the only location that reaches the nominal 1000 lux without extra "spotlight" illumination is the MWL However the MWL does have 4000 lux of lighting directly above it so one would expect it to easily reach the 1000 lux mark.

    The DP with its 2500 lux has an LED light in the usually spot for a light globe in the DP. The MWM also has a bright LED spot enabling it to reach 2400 lux. The TS LED spot is in the OH guard so is very close to the table top and this is why it reaches 17000 lux but it's only for a very small area abut 150mm in diameter in front of the TS blade.

    I do have several other spots that I move around as needed, eg to better illuminate the BS.

    I do have a lot of crap hanging in the shed's ceiling space and even where an operator stands can block a lot of light - which is why I tend to use spots.
    The shed is also low and very full so there is limited chances for light from one lighting fixture to get across into another space.

    Last week I also upgraded my lighting above my electronics workbench inside the house by replacing the 6000+ lux of CF globes with 10000+ lux of LED spots.
    There are also 2 other LED spots and an LED Mag lamp.
    The ambient lighting in the middle of the bench was ~ 50 lux
    With all my lights on, the max illuminance in the middle of the workbench is around 3800 lux for an area about 250 mm in diameter dropping down to 2800 lux over an area about 800 mm in diameter.
    The visual increase in brightness by using LED compared to CF globes is nowhere near what I might have expected but then this reminded me that human vision has a logarithmic responses to brightness so to increase the apparent brightness by 2X requires around 10X more illuminance.

    I hope this shows you why you can never have too much lighting in the first place.

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  3. #2
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    Perth
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    Default

    Just thought I'd post a picture of the upgraded lighting above the electronics workbench.

    The lighting support structure is a home made macro photography stand from which I suspend d a number of items.
    I also made all 4 of the light fixtures attached to the stand from white painted Al sheet metal.
    Originally the 4 fixtures held 20W CF lamps but these lamps are now about 6 years old and one died last week so rather than replace it with the same thing I decided to go LED.
    The new lamps are Osram 27W LEDs and as you can see I've used two daylight (2700 lumens) and two warm tone (2430 lumens) and each can be switched in/out as required.
    There are 36W (3240 lumens) versions of these lamps
    There are also 2 other15W LED spots (one not in picture) and a 5W LED magnifier lamp.


    Os26WLEDs.jpg

  4. #3
    Join Date
    Jun 2015
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    Wolvi
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    Default

    Good thread Bob, I'll be paying a bit more attention to this over the next little while as the lighting at my place is chronic, thanks mate.

    Before I go though, I do have one question, do you grow anything in your workshop, just askin.

  5. #4
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    Quote Originally Posted by Feckit View Post
    Good thread Bob,

    Before I go though, I do have one question, do you grow anything in your workshop, just askin.
    just ideas to keep all us yobbos happy
    Life expectancy would grow by leaps and bounds if green vegetables smelled as good as bacon.

  6. #5
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    Jun 2015
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    Default

    Well, its more a case of waste not.

  7. #6
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    Default

    Quote Originally Posted by Feckit View Post
    Good thread Bob, I'll be paying a bit more attention to this over the next little while as the lighting at my place is chronic, thanks mate.

    Before I go though, I do have one question, do you grow anything in your workshop, just askin.
    No but several visitors have asked me the same question.

  8. #7
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    Aug 2007
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    Saskatoon, SK, Canada.
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    Default

    Bob how does the Lux Meter you borrowed compare to a phone app like LUX on an iPhone? Is the phone remotely close?

    Pete

  9. #8
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    Quote Originally Posted by QC Inspector View Post
    Bob how does the Lux Meter you borrowed compare to a phone app like LUX on an iPhone? Is the phone remotely close?

    Pete
    Good question.

    I looked int this a few years ago and this link shows the typical problems involved when using mobile phone light meters.
    https://www.dial.de/en/blog/article/...g-illuminance/
    Unlike Sound pressure level apps on mobile phones which are usually accurate to +/- 10% for free apps, through to +/-1% for Apps like "Sound Meter Pro" by faber Acoustics when run on an iPhone.
    mobile phone, Light meters on mobiles were found to read too low by 113% and too hight by as much as 63%.
    This is why I decided to borrow a proper Lux meter.

    Just for fun I downloaded the free LUX light meter
    There are 3 reviews for this product, none of which inspire confidence , see https://itunes.apple.com/us/app/lux-...171685960?mt=8
    As usual with some free apps the ads are a right PITA
    The results were all over the place from about 50% too low to 15% too high.
    It is also seems highly directional and does not integrate the light from around the phone.

    I also downloaded the free version of "Light meter Pro".
    The readings are hopeless ranging from 10X too low 2x to high - The adds are also very annoying.
    After a while it redirects you to the App store to buy the product.
    It only costs $4.49 so I might buy the pro version to see how it fares

    If you want to measure illuminance cheaply I suspect a $40 Lux meter on Ebay will do a better job than any free mobile App.

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