The cast aluminum box will corrode until it is white powder. If they haven't already, the 6-32 screws will corrode to a point where they will be siezed in the threads, and will break off rather than unscrew. The "brackets" across the front of the box will most likely twist out or just fall apart.
I think that's what 300.6 (B) is about: "Non-ferrous raceways, cable trays, cablebus, auxiliary gutters, cable armor, boxes,..........embedded or encased in concrete or in direct contact with the earth shall be provided with supplementary corrosion protection".
Re: Ground box? Post Light?#124552 10/15/0609:34 PM10/15/0609:34 PM
this is a surface mounted box, that looks as though it is mounted within the concrete lighting support. I agree that there is a good chance it may corrode. It is hard to tell the wiring, so I will only post about the box.
Re: Ground box? Post Light?#124554 10/16/0605:57 AM10/16/0605:57 AM
These lights were put in about 20 years ago, by general contractor whose expertise was in cement work. Suffice it to say that he has provided me with a steady source of income....
The zinc (or aluminum) Bell boxes are badly corroded. Concrete is alkaline, as is our soil, and those materials are quite vulnerable to alkalais. The poles, being 2 1/2" Rigid, have not corroded at all.
Among the details not visible: - That plastic plbg elbow coming in the side is part of a short length, covering but the last foot of UF. The UF is buried maybe 6" down. MAYBE. - In the bottom of the box is a 12" rigid nipple. This shields the UF as it passes through the block, and on to the next light. - Yet another piece of UF goes out the right. That piece is cast into the concrete, until it passes out the bottom of the block, and turns to enter the bottom of the post. Finally- - There is essentially no wire to work with in the box.
When new, these blocks were flush with the ground. Then sod was added. Growth over time has meant that many of these blocks are completely under the grass.
I believe the plumbing el was used to make a smaller target for the lawnmower. Not to worry; it has still been hit, and the pipe broken at the block!
What this place has taught me is: - Cut a hole in the side of the pipe, and use a PVC sweep to pass the wire through the block, and into the pole. Then you have a chance of replacing the wire; - Use a proper handhole at the base of each pole for your splices; and, - Make sure your wires are deeper than the gardener can dig with one shovel scoop.
Re: Ground box? Post Light?#124556 10/16/0611:55 AM10/16/0611:55 AM
Reno correct me if im wrong but uf cable here in mass must be buried to a minimum of 18". 6" just wont cutit. What are the requirements where you are? Either way its a shoddy installation at best. I have done lighting for parking lots before and we always use pvc schedule 40 buried 18" below grade with the caution tape on the pipe and 12" above the pipe then buried. I also totally agree with you about the box corroding in the cement. These were not designed for this purpose. Shoddy at best and I know it could not be to code even 20 years ago.