wiring a metal building in HI.

pmgtwo51 · Jun 8, 2021

I'm located on the East side of the Big Island, Hawaii. Due to the copious amounts of rain and the ever-present Sulphur gas from Kilauea Volcano which ranges from virtually imperceptible to close the doors and windows and wait till the wind changes direction. I've purchased a Steel Master metal building, 20' x 30' to be used as a part time garage and place to tinker and make stuff. I'm currently in my 15th month, waiting for the Building Permit approval from the county but that's another story. Because of the humid and occasionally corrosive environment, I would really like to run sch 40 pvc conduit, j-boxes and device boxes. I don't have a current NEC book but I believe the main issues are, different heat ratings for pvc than metal requiring de-rating the conductors and not installing pvc where it can be physically damaged. I plan on having HELCO run the aerial service drop to the end of the building: weather head, 2" ridgid mast to the Milbank, to the interior mounted 200-amp panelboard, then come out of that with pvc for all of my branch circuits. I also want come out of the bottom of the panel, into the slab, into a trench, alongside the domestic water H2O line (at least 1' distance between the two) approx. 80' into the slab for the house and mount a 100-amp sub panel in the house. I'm reluctant to go to the Planning Board with any questions because I think I'm close to getting permit approval, not that they've been much help in the past. I've also asked three different "electricians" and gotten three different answers. I fear the problem is they don't want me doing any of the work myself; potential money out of their pocket. Any thoughts of suggestions would be welcome. Oh, and as an aside, I retired from the Dept. of the Navy, civilian, 20 years as a Govt. electrician, and I didn't come here with enough money. But it's all good. I'm living in Paradise!

DPG · Jun 8, 2021

Great story. Different to the usual run of the mill stuff!

Our American member megawatt will probably be able to help you.

Megawatt · Jun 10, 2021

pmgtwo51 said:
I'm located on the East side of the Big Island, Hawaii. Due to the copious amounts of rain and the ever-present Sulphur gas from Kilauea Volcano which ranges from virtually imperceptible to close the doors and windows and wait till the wind changes direction. I've purchased a Steel Master metal building, 20' x 30' to be used as a part time garage and place to tinker and make stuff. I'm currently in my 15th month, waiting for the Building Permit approval from the county but that's another story. Because of the humid and occasionally corrosive environment, I would really like to run sch 40 pvc conduit, j-boxes and device boxes. I don't have a current NEC book but I believe the main issues are, different heat ratings for pvc than metal requiring de-rating the conductors and not installing pvc where it can be physically damaged. I plan on having HELCO run the aerial service drop to the end of the building: weather head, 2" ridgid mast to the Milbank, to the interior mounted 200-amp panelboard, then come out of that with pvc for all of my branch circuits. I also want come out of the bottom of the panel, into the slab, into a trench, alongside the domestic water H2O line (at least 1' distance between the two) approx. 80' into the slab for the house and mount a 100-amp sub panel in the house. I'm reluctant to go to the Planning Board with any questions because I think I'm close to getting permit approval, not that they've been much help in the past. I've also asked three different "electricians" and gotten three different answers. I fear the problem is they don't want me doing any of the work myself; potential money out of their pocket. Any thoughts of suggestions would be welcome. Oh, and as an aside, I retired from the Dept. of the Navy, civilian, 20 years as a Govt. electrician, and I didn't come here with enough money. But it's all good. I'm living in Paradise!

It is fine to run PVC conduit and use PVC junction boxes. As far as the the de-rating the wire that applies for conduit on roofs where it gets real hot. You should be fine. As far as physical damage to the raceway that applies to flexible sealtite

pmgtwo51 · Jun 10, 2021

Megawatt said:
It is fine to run PVC conduit and use PVC junction boxes. As far as the the de-rating the wire that applies for conduit on roofs where it gets real hot. You should be fine. As far as physical damage to the raceway that applies to flexible sealtite

Thanks for the input Megawatt.