tree lighting

[sitelights]

If the trees are the focal point the trees should be uplighted. On trees with a large spreading canopy you may need to use multiple fixtures. We usually triangulate and use a fourth fixture for the trunk. An illuminated canopy without trunk lighting looks a bit strange. A tree with branches 25' from the ground can be illuminated with a single fixture with the appropriate lamp. A table of photometrics can be used to determine the necessary beam spread to match the diameter of the canopy. Example: an MR-16 20w 40 degree BAB lamp would create a circle of light about 20' across if the canopy started at 24' from the ground. These tables can be found in lamp catalogs and in some fixture catalogs. The 20w lamp would produce about 1 footcandle (fc) at 24'; a 50w EXN lamp would produce about 3 fc under the same circumstances. With multiple fixtures 20w lamps would be enough; a single fixture would need 50w if more than just a glow was desired.

If the focal point is beneath the trees (a walkway or a patio, etc.) then downlighting would be preferable. To avoid glare the downlights should have a regressed lamp or a shroud and should be aimed almost straight down. Again, photometric tables will guide you in your choice of lamps. Some trees, particularly "prunus" varieties, should not have screws driven into their bark and never use screws of copper or copper alloys in any tree.

Maintenance of tree-mounted downlights is always a problem since you must mount at least 24' above the ground to keep the light beam out of ordinary line-of-sight. Use stainless steel screws and staples; loop a cable tie through the staple and around the low voltage wire with enough slack to allow the wire to travel through the loop. Tree growth will otherwise engulf the cable or pull it taut enough to break. At a 24' working height you should always have an assistant to steady the ladder.

[tscheuren]

Thanks for this most helpful reply.

[bhebert]

How do you read a table of photometrics? For instance, what type of fixture would you need to up light a 40 foot canopy with a 3 foot diameter trunk?

[Eden Lights]

Take a look at this free software on GE lamps, I use it all the time.

http://www.gelighting.com/na/specoem/lightbeams.html

[K.L.L]

Take a look at http://www.uicorp.net/vistaphotomMR16.htm
This should help a bit. Note that it is not the fixture which determines the photometrics. The photometrics are determined by the lamp. A fixture can affect the photometrics if for instance the lamp is recessed deep into the fixture. The fixture simply powers the lamp. The wattage you deceide to use will simply be determined by light polution (street lights and etc) and personal taste. If your yard is very dark and you like the subtle look, go with the 20w BAB. If you have existing light to compete with, or you like the higher light levels, you could go with the 35w FMW. Either way, start with the 20w, and then try the 35w, to see which you prefer. I would not bother with the 50w lamps (too hot for my taste (unless you like frying eggs, hehehe). I should also mention and it should not be overlooked, that you use the proper equipment (fixtures rated to handle the wattage). As far as the trunk; the diameter does not make much of a difference. Set the lamp a couple feet from the trunk and aim it up at about 80 degrees or so. Make adjustments until it makes you smile.....If you use multiple fixtures to light the canopy, make sure you are not sticking them in the middle of your yard to become mower food. You might want to use a 60 degree lamp, but from my experience, most of the additional spread is cut off by the fixture. The information above would be assuming that you are using an MR16 lamp. Hope this helps.
With kind regards,
K.L.L

It appears the foot candle numbers b/w the flood and wide flood on the 20w and 35w lamps are reversed. Oh well, you get the idea.

[180q]

Originally Posted by Eden Lights

Take a look at this free software on GE lamps, I use it all the time.

http://www.gelighting.com/na/specoem/lightbeams.html

That useful link appears to be outdated. Here's the new location:

GE photometrics

[Abonna]

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