I have 3ea single phase RTU @ 8.4a each. on a commercial building, It was necessary to install a new 15kVA 480-208/120 X-former as there was no 208 available in the vicinity. The secondary (40a) over-current device is installed next to the X-former in the roof access closet. From there I made a roof penetration and installed a 3/4 co with 4#8 and a #10gr (neutral for rt-rec only which also got it's own private fuselable pull-out) for about a 130ft run. Nice and clean on the parapet wall. At each RTU I installed a NEMA-3 6X6X4 and tapped the #8s to feed a 30a 1phase pull-out disconnect, fused at 20a which in turn feeds the RTU's which are right there and clearances are all in order.
Now, my Glendale CA inspector turned this system down as he felt that the tap rule pertained to the over-current device at the X-former. My understanding is that the X-former secondary EXO is protecting the #8s throughout the installation and the single phase (fuseable) pullout are the only devices that would exercise and comply with NEC 240.21.
This whole scenario is odd to me because of the great many instances of a feeder set pulled into a gutter and tapped for misc equipment. This is done all the time and I have done it a great number of times not only for HVAC equipment but for various machines and panel-boards. It is very possible that the inspector is merely confused about the installation and wrote a correction which needs to be more clearly understood as I am having trouble finding a clear description of the "tap-rules" in NEC 210-240
Thanks for your help and input.
Now, my Glendale CA inspector turned this system down as he felt that the tap rule pertained to the over-current device at the X-former. My understanding is that the X-former secondary EXO is protecting the #8s throughout the installation and the single phase (fuseable) pullout are the only devices that would exercise and comply with NEC 240.21.
This whole scenario is odd to me because of the great many instances of a feeder set pulled into a gutter and tapped for misc equipment. This is done all the time and I have done it a great number of times not only for HVAC equipment but for various machines and panel-boards. It is very possible that the inspector is merely confused about the installation and wrote a correction which needs to be more clearly understood as I am having trouble finding a clear description of the "tap-rules" in NEC 210-240
Thanks for your help and input.