# which will give more light

Discussion in 'Electrical Engineering' started by Eric and Megan Swope, Jun 4, 2005.

1. ### Eric and Megan SwopeGuest

Hi everyone. In my basement, I have a drop ceiling. In the spot where I
have the 2 clear tiles for lighting, instead of fluorescent lights, the
original homeowner pout in light housing for normal screw in light bulbs
that are nailed to the floor joists. The maximum watt light bulb I can put
in these housing is 150 watt. So in my basement now I have 2x150 watt light
bulb illuminating my area. My question is this, what will give me an
overall brighter basement, 2x150 watt light bulbs, or if I buy two
fluorescent worklights, each one holding 2x40 watt fluorescent tubes for a
total of 4x40 watts (I believe the brightest fluorescent tubes are only 40
watts?). I know simple math seems to say the 300 watt total from the light
bulbs would do it, but I would say every 2 months or so one of the 150
watters blows out (we use our basement a lot, so the lights can be on for
hours at a time). Cost of these bulbs isn't a major issue however, the
lighting is more so. Any advice is appreciated.

2. ### RBMGuest

You can buy four light four foot florescent fixtures as well. You don't
determine light output by wattage. Find a chart on the net that gives you
the lumens of each type lamp you want to compare

3. ### Andrew GabrielGuest

One 40W fluorescent tube is going to be equivalent to something
around a 150W filament lamp. You can easily lose half the light
in the fitting with filament or fluorescent lamps, so a comparison
of the raw filament lamp verses raw fluorescent tube light output
won't necessarily give you the whole storey -- it will also depend
on the type and positioning of the light fitting.

4. ### Doug MillerGuest

Fluorescent lights are much more efficient, and emit a *lot* more light per
watt consumed, than incandescents. You'll probably get about twice as much
light from 160 watts of fluorescent tubes as from two 150-watt incandescent
bulbs.

Compare the rated lumens output on the packages, not the wattages, when
comparing fluorescents to incandescents - that's a measure of the actual light
output.

Bottom line: incandescent bulbs emit most of the energy they consume as heat,
while fluorescents emit most of it as light. If your objective is to heat your
basement, use incandescents. If you want to illuminate it, use fluorescents.

And if you prefer the yellow, "warm" glow of incandescent bulbs to the stark
white "cool" light of fluorescent tubes... get compact-fluorescent bulbs that
screw into a standard incandescent socket. Best of both worlds: warm glow, and
energy efficiency.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?

5. ### Andrew GabrielGuest

Or buy 2700K fluorescent tubes (at least, they're available in
the UK if you look for them), and they would blend well if you
also have any other filament lamps around. 3500K should be fine
too if the lighting level is high and you don't need to blend
with other filamane lamps. Anything above this can start looking
cold unless the lighting level is very high.

6. ### operator jayGuest

If you want dimmability, you could stick with incandescent. It is cheap and
easy to dim. By the way, if you do dim incandescents, even a little, they
will live way longer. But, as other people have said, fluorescent lamps
will put out much more light (lumens) per Watt. With an acrylic lens
recessed fluorescent fixture, you will probably get about half of the lumens
out of the fixture. I don't know what type of fixture your incandescent
lamp is in. If it's a bare bulb hanging down into your space, you will be
getting a lot of its lumens.

j

7. ### Andrew GabrielGuest

So, a 60W lamp running at half voltage is about 21W power consumption
and about 10% of full light output, i.e. equivalent to a 6W lamp.
A 4W fluorescent tube which is going to be roughly similar light
output to the two underrun lamps.

So, I guess you've been wasting (2 x 21) - 4 = 38W for 30 years
in lamp inefficiency due to underrunning inappropriate lamps,
which comes to a total of 10 megawatt-hours of wasted energy.
That would have cost me £1000 (1800\$US) at todays prices.
You would have needed around 10 new tubes over that period,
but those would have cost you less than 2% of the money wasted.

8. ### KenGuest

It's about 5 times more efficient.

9. ### AnthonyGuest

Concurring with the other posters, you could put (2) 4-bulb florescents
and have many x the lighting, and still just be using 160 watts of power.

--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

http://www.machines-cnc.net:81/

10. ### --Guest

You can select different incandescent and fluorescent bulbs with different
characteristics, so the answer is all over the place and always right. How
much light you get from a bulb depends on where you measure the light,
spatially and spectrally.
E.g, a 100 watt par 40 spot will have more and less light than a 100
watt par 40 flood and it can have more light at some illuminated areas than
do some 100 watt fluorescents.
There are standards as to the shape and distance used to get that bulb's
lumen/light reading on the package, but most bulbs don't track you around
the room, so you have to make a few decisions.

For the home, it is a bit simpler than choosing light commercially- many
books on the subject leave your head hurting over candela, lumens, lumens
per, temperature K, etc. - but the basics still apply:

Primary decision is what do you want to do in the space?
Usually, and obviously, it involves seeing detail (like sewing), or not
seeing so the imagination can fill in gaps (like in a club).
Hence there are dimmers in multi-use spaces on some overhead fixtures,
and there is incandescent spot lighting on tables and wall decorations mixed
with fixed fluorescent overhead area lighting.

Some guidelines -
- Seeing well requires 1) contrast and 2) proper kind of lumens on the
surface and 3) lack of conflicting contrast.
In other words, you see better with more light and less shadow, and it
also means that the less contrast you have (e.g., sewing dark on dark), the
more lumens you need. (The rule of thumb for commercial space is that a
10% decrease in contrast in the work requires a 100% increase in the lumens
on the surface.)

- often, where you put the light has more effect than how much. Spots vs.
floods, a 60 watt par 30 spot on a table vs. a 40 watt tube in an overhead
fixture, etc. and placing sources so there is little shadow and yet a light
source isn't in your eyes, either.

- bulb efficiency is measured in lumens per watt (almost always measured
at a voltage), and overall efficiency is measured including the cost of
changing the bulb - which is why a 130 volt bulb giving poor lumens per watt
(vs. the same 120 volt high lumen-per-watt bulb) is sometimes more
cost-efficient when the bulb is hard to get at.

Consider using several kinds of lighting to supplement the likely ceiling
fluorescents (avoid shop lights, imho), and consider adding low voltage
halogen spot lighting to the fluorescents, which often doesn't require the
same level of electrical work that a 120 volt installation does

---hope it helps