Thread: Some actual shed illuminance measurements.

Thanks for the info Bob, I have the lights on the ceiling about 3.0mt above the floor, replaced 2 standard down lights. I will checkout Bunnings here and also the electrical wholesaler next week when I get out of isolation. The Bunnings ones look better, I had an electrician install the ones a got so I assume he would have checked the earthing of the fitting I think he just connected the wire on the fitting directly to the wires in the roof, no plugs.

Cheers. Rick

Thanks Rick.

I've been doing all sorts of electrical tests in my shed lately and it's interesting to see what electrical stuff (transients) flies around when machines are switched on and off even if they are on separate circuits.

For example.
My DC and compressor are on their own 15A circuits/breakers
My 15A compressor is left turned on at the wall/GPO but not actually running so there's voltage thru to the compressor pressure switch but the motor is not running so there's no amps.
However, if I turn my DC on or off there is the equivalent of a 1s/1A pulse (transient) sensed in the compressor cable.

If my DP (which is on a separate 10A circuit) is turned on/off there is 1/2s 100mA pulse sensed in the compressor cable.

These don't seem like much but they could upset cheap circuit components. This is another reason why things need to be properly grounded

The Bunnings ones should be much better - for a start they have a 2 year warranty. Also I suspect the claimed lumens will be closer to reality.

Seems this would be the appropriate posting for this.

Searching about to find the calculations for workshop lighting and I fell into a forum and found this on a UK site so it looks like it translates okay:

the degree of illumination is called illuminance, and it's measured in lux (that's lumens per sq M). Fortunately the eye can accomodate to a wide range of illuminance, as daylight provides about 100,000 lux in sun, and moonlight 0.2 lux. Of more practical use, minimum illuminance needed for critical tasks like sewing or reading or woodwork is about 300 lux at the task. People over 50 may need up to twice this level.

Light fittings vary in practical effectiveness according to room size, mounting height and overall wall and floor colour. For simplicity, in a workshop with lighting at height 2.5 to 3M and using a good reflector, with white walls and light floor, the Coefficient of Utilisation (C of U) is about 0.5. For a very dingy workshop, could be as low as 0.3.

LIght fittings get dirty, and light is lost as a result. If you spring clean once a year, allow a Maintenance Factor (MF) of about 0.6 (0.8 if you do it monthly!)

You calculate total lumens required (lamp output is given in lumens) thus:

Installed Flux= desired illuminance x floor area/C of U x MF

For workshops, desired illuminace is 300 lux.

My workshop is 5.5M x 5.5M, very light in colur, and cleaned once a year, so the

total flux needed = 300 x 5.5 x 5.5 / 0.5 x 0.6 which comes out to 30,250 lumens

The lumens could come from:

Lumens
1300 - 100W filament bult
3150 - 200W filament bulb

1100 - 20W energy saver fluorescent

2100 - 900mm fluorescent tube
3000 - 1200mm fluorescent tube
4800 - 1500mm fluorescent tube
5200 - 1800mm fluorescent tube

light outputs for tubes allows for fading during life, and is less than the 'new tube' figure
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Seems to me LED battens or Panels would be far more suitable than fluoro's, but the lumens are the lumens whether you use fluoro's or led's

Doing a calculation for my proposed shed with a desired lux of 500 I get:

500 Lux X 6m X 8m / 0.5 then X 0.8 (assume clean lighting) = 28,800 lumens

Assuming I use 3000 Lumen battens I would need 9.6 fittings.

I am planning on 3 row of 3 plus two dedicated over my workbench.

Given the cheapness of the fittings these days I will probably use double that and have the second lot on a
separate circuit and only switch on when they are required.

Hope this is useful for those thinking about a light upgrade.

Cheers,

Scott.

Scott, was the any information on age allowance as we get older?

A general guide is you need twice as much lighting at 60 years of age to see teh same level of details as you do when you are 30 years old.

What Bob said above...I figure I will nedd 500-700 lumens when I get to building the new shed.

During a house reno I pulled all 65 halogen downlights out and put in LED downlights and everyone complained it was too bright....for about one night. Recently Mrs P. had to house sit in a house with incandescent lights and she said it was like living in a cave so I guess she changed her mind about the LED's.