I have a customer that would like me to mount some PAR 30 floodlamps in his trees for a horseshoe pit. I have seen this done a number of times, however, I am not sure of the best and most reliable way to do it.
Power is coming up from the ground as 1/2" PVC. I would like to transition to RGC and go up the tree to a WP box, and mount the lights to that. However...how does a tree growing/blowing in the wind affect this??? Where does a tree gain its height?? If it is from the bottom, I think that my plan won't work! Anybody have any ideas on how to aproach this?
I did this several years ago with IMC. I bent the pipe to conform with the shape of the tree and held it with straps and screws as I would with any wooden structure.
Trees get wider, growing from the center, and gain height from the top. I'd consider any shifting of the pipe over the years to be a maintenance issue, like mounting to a 4X4 post that will eventually rot.
Something to also consider is the growth of leaves against the bulbs.
Re: Mounting Lights in Trees#52104 05/18/0509:22 PM05/18/0509:22 PM
225.26 Vegetation as Support. Vegetation such as trees shall not be used for support of overhead conductor spans. Where overhead conductor spans are attached to a tree, normal tree growth around the attachment device causes the mounting insulators to break and the conductor insulation to be degraded. The requirement in 225.26 reduces the likelihood of chafing of the conductor insulation and the danger of shock to tree trimmers and tree climbers. The 2002 Code has deleted the exception to 225.26 that appeared in previous editions, and trees are no longer permitted as support of overhead conductor spans, even on a temporary basis. However, outdoor luminaires and associated equipment are permitted by 410.16(H) to be supported by trees. To prevent the chafing damage, conductors are run up the tree from an underground wiring method. See 300.5(D) for protection of conductors.
So what happens when the tree grows, and pulls the whole install apart?
Mark Heller "Well - I oughta....." -Jackie Gleason
Re: Mounting Lights in Trees#52106 05/18/0509:39 PM05/18/0509:39 PM
Definitely need some sort of flexible conduit if you want this to last any amount of time, can't beleive it is even legal to install on a tree but I guess it is.
The worst choice would be something like RGC, there is just no give in it. How about a combination of schedule 80 pvc with expansion couplings and sealtight ?
Visiting Disney world, I saw a lot of this type of installation on trees for attractions. ( thats right...I was looking at electrical as I'm standing in line..does'nt everybody ?) They used UF cable though, must have some permission from AHJ I would guess
Re: Mounting Lights in Trees#52108 05/19/0501:02 AM05/19/0501:02 AM
These are pine trees, they just go straight up, so luckily no kids on them! I tried to convince the guy otherwise, but there are no other places to mount the lights.
I am now leaning in the direction of sealtite up one side, I just hope it holds up to the weather/sun. I'd strap it every 2 feet and leave some slack in everything. Sch80 Pvc might work too, I think I'd use sealtite for a few feet out of the ground, then PVC to the box.
Thank you for the replies, it's given me some stuff to think about. Any other ideas, please post! Mike
Re: Mounting Lights in Trees#52109 05/19/0501:52 AM05/19/0501:52 AM
The core timber of a tree is solid, and on the trunk any point will remain practically constant to ground level. Growth is outwards on the trunk, the diameter increasing each year, up to 3/4" per annum on a pine. Height on a pine is strictly off the growth tip, (sometimes several tips). So the problem is, the tree growth eventually envelops and buries the fixings. Fixings may then eventually present a hazard when the tree is cut for firewood or lumber, as the buried fix may be hit by a chain/bandsaw. So the best fix is to use long stainless large head nails through a reasonable-sized non-corroding fixing plate laid on the bark, which can be dressed back to provide a flat. Now as the tree grows, it will gently pull the nails with it each year, keeping the plate on the surface, yet giving a good fix. Alan