| Rob,
Toward the end of this, I'll tell you what we did in a similar
situation. But, the general answer to "What do I need for
outdoor lighting?" depends on a *bunch* of factors:
1. How bright you want the area(e.g. Do you just want to be able to
find the door/gate and bring the horses in? Or do you want
enough light to jump a combination jump?)
2. The amount of area you want to cover
3. The height at which you can mount the light fixtures(Higher
mounting gives more coverage from the same fixture)
4. How quickly you want the light to come on after you flip the
switch(Some types take a while to warm up)
5. Whether or not the "quality" of the light is important etc.
(Some types make everything look gray. Others will let you
see color differences)
6. Expected bulb life(i.e. how frequently are you going to have
to climb a 16 to 30 foot high ladder to change the stinking
bulbs?)
BTW, above I said that some types take a while to warm up. That's true.
It's also true that they go off if there's so much as a flicker in the
power supply. They take almost as long to come on after a flicker as
when they're cold. That may be a factor if you have frequent power
interruptions and/or might power these lights off a generator. We have
both situations so we've become very aware of what kind of lights go
where...
Re "The 400W costs ~$200, uses 2.5 amps"
Since there's a direct relationship between wattage, voltage and amperage
all 400W lamps use the same amount of electricity. However, they vary
on the amount of light they produce with that eliectricity. For
example, ordinary household bulbs convert about 80% of the electricity
they use into heat. Different combinations of gases and elements
produce varying degress of efficiency in converting electricity into
light.
The sodium fixtures give off a yellow-orange light and they pretty much
make every thing look grey. They take several minutes to warm up.
Sodium fixtures are popular because they are very efficient at
converting electricity into light. However, it's "poor quality" light,
IMHO because it's hard to see anything, especially colors.
Typically, the bulb for a 150W sodium fixture looks like a giant
household bulb with the round end being about 4" in diameter. Most
sodium fixtures are "globe" type things and can't be aimed.
Mercury vapor fixtures give off a white light and are more expensive to
run than a sodium fixture(i.e. you get less light per watt). Like
sodium fixtures, the mercury vapor fixtures take several minutes to
warm up. A mercury vapor bulb is similar in size & shape to the sodium
bulbs. Most mercury vapor fixtures are also globe types that can't be
aimed. Most lights that produce white light will let you see color.
Halogen fixtures give white light too. They are available in 300W
or 500W sizes for about $15 each. The bulb is a 3" or 4" tube about
3/8" in diameter(i.e. they're small). They don't give as much light per
watt as mercury vapor fixtures BUT they come on immediately. These
fixtures can usually be aimed. The ones I have on my driveway are
rectangular and can swivel the head up/down. Since they screw into the
box cover, you can aim them left/right too if you mount the electrical
box parallel to the ground.
Metal hallide fixtures work well for arenas or large paddock areas.
They give off white light; take a while to warm up; they're efficient;
400W lamps cost about $200 and can be wired for either 120V or 240V.
The ones we have in our arena(See notes 1486.55 - .60) can be aimed
left/right up/down.
SIMILAR SITUATION:
What we did to provide good light around a barn and the adjacent
small(1.25 acres) paddock is install halogen fixtures on each end
of the barn. We actually mounted them on poles sticking out from the
ends of the barn. We chose to use 2 lights on each end so that we
could light the whole area uniformly by aiming 1 light on each end
towards the corner of the paddock and the other towards the center.
We used the 300W rectangular halogens taht you can buy most anywhere
for $15 or less.
Hope that helps
John
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