Before anyone blindly answers this, I'd like to first request that only people in the power transmission industry answer, as they are the only ones likely to know.I have a customer who is asking to mount several very large pieces of electrical equipment 15 feet in the air, mounted to a large structure. All of these equipment pieces are 5000 or more pounds and pad-mount by design. I am questioning this request on the basis of legality. Basically, I am curious to know, is there anything in the NEC that says mounting pad-mount equipment overhead is illegal? If so, I could really use a hint as to what section of the NEC code.
I don't believe that there is anything in the NEC that addresses this. Obviously, installing anything on a structure presents challenges that require the attention of a qualified structural engineer. And depending on the location, you could be facing some additional concerns. You would need to check on seismic activity in the area, and since 'pad mount' equipment has a broad profile, wind-loading could be more challenging if you have a wind-force specification to meet. The other issue you would need to consider is whether installation on a structure presents any particular safety concerns. Without knowing any more, my inclination would be to think that you might want to provide an enclosure around the structure to prevent civilians (rmeaning 'teenagers and drunk college students) from climbing it. Just out of curiosity - why does your client want this? We know that the client is always right - even when he insists to stupid things. I trust there is a good reason for asking for something that is bound to increase installation cost by probably 100%.
