According to Wikipedia,
Electrical bonding is the practice of intentionally electrically connecting all metallic non-current carrying items in a room or building as protection from electric shock. If a failure of electrical insulation occurs, all metal objects in the room will have the same electrical potential, so that an occupant of the room cannot touch two objects with significantly different potentials. Even if the connection to a distant earth ground is lost, the occupant will be protected from dangerous potential differences.
After reviewing the alternatives, they concluded that we will run rigid (metal) conduit coming from the roof in the 20 ft interior concrete wall to a metal junction box. The metal junction box will be accessible from the crawl space under the raised pantry floor. The metal junction box will carry a ground wire to the junction box in the Mechanical East room, which is where the inverters are located. Thus, the entire solar system will be bonded to the house.
Placing Inside Layer of Reinforcing Steel
The retaining walls around the perimeter of the house have two layers of reinforcing steel (rebar). The exterior layer is #5 (5/8 inch diameter) and the interior layer if #4 (1/2 inch diameter). The full exterior rebar layer was completed and now the inside layer is being put into place.
Establishing the Offsets on the Structural Slab
An important step at this stage is to establish the inside wall locations so the walls are straight and square, and at the correct elevation. We had our licensed surveyors establish ponts on the structural slab and it is our responsibility to put those points into context relative to the structural and architectural plans. We want the steel columns to rest on the plates that will support the steel beams. All of these components need to be in perfect alignment.
Dunbar and Craig sent us the DWG files from Tuesday so John Rider (Jrider + Design) imported those into our ArchiCAD model and then positioned the existing house and new lower level relative to those points. Bryan will establish the correct offets relative to the point that were surveyed on Tuesday.
The diagonal distance between the four offsets should be 67 ft 3 inches.