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which will give more light

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

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  1. 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. RBM

    RBM Guest

    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. 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 Miller

    Doug Miller Guest

    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

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

    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.

    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. 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 jay

    operator jay Guest

    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.

  7. 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. Ken

    Ken Guest

    It's about 5 times more efficient.
  9. Anthony

    Anthony Guest

    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.


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

    Remove sp to reply via email
  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
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