nascaracing
Member
- Location
- Las Vegas, Nevada
Just looking for clarification/understanding that the installation is correct and to code. There are (4) 95' X 140' steel buildings; on three of the buildings there is a #4awg or larger bare conductor grabbing the steel rebar at the lowest position possible, with a tail of at least 20' outside the slab for a ground rod, and another 10' coiled for the transformer. The building will be fed with 480/277V at one MDP which branches out to four step down transformers to 120/208V. These buildings will be primarily used for maintenance/repair of military vehicles. This grounding method is done at the MDP and the four transformer locations inside the building
Now with that said the internal wiring of the building will remain a 5-wire system (3 hots, 1 grounded, 1 grounding) to the consumer panels (there will be four - six panels) and no more grounding will be needed for the operation of this electrical system.
The one building in which the rebar (ufer) was not done as long as the building steel is bonded with the electrode conductor to minimum two ground rods; this is an acceptable method for the grounding of this electrical system??
Also of note at the first MDP is where the initial bond will be, to establish ground.
Now with that said the internal wiring of the building will remain a 5-wire system (3 hots, 1 grounded, 1 grounding) to the consumer panels (there will be four - six panels) and no more grounding will be needed for the operation of this electrical system.
The one building in which the rebar (ufer) was not done as long as the building steel is bonded with the electrode conductor to minimum two ground rods; this is an acceptable method for the grounding of this electrical system??
Also of note at the first MDP is where the initial bond will be, to establish ground.
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What you describe seems to be compliant. To check yourself, see 250.52(A)(2) and 250.30(A)(3)