On Tuesday, July 14, 2015 at 1:04:12 PM UTC-4, krw wrote:   
       
   > BTW, water pipes are no longer allowed as the building ground (just the   
   > opposite, though - they are grounded).     
      
   If you read the totality of the language used in Section 250.50 of the   
   National Electrical Code (NEC) as published in the United States you will see   
   that not only is any underground metal water piping that is Three Meters of   
   more in length permitted to    
   be used as a Grounding Electrode, If it is present it must be used.  Shall' as   
   used in the NEC, is the prescriptive rather than the permissive term.     
      
   250.50 Grounding Electrode System   
   All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are   
   present at each building or structure served shall be bonded together to form   
   the grounding electrode system.   
      
   250.52 Grounding Electrodes   
   (A) Electrodes Permitted for Grounding.   
   (1) Metal Underground Water Pipe. A metal underground water pipe in direct   
   contact with the earth for 3.0 m (10 ft) or more (including any metal well   
   casing bonded to the pipe) and electrically continuous (or made electrically   
   continuous by bonding    
   around insulating joints or insulating pipe) to the points of connection of   
   the grounding electrode conductor and the bonding conductor(s) or jumper(s),   
   if installed.     
   (2) Metal Frame of the Building or Structure. The metal frame of the building   
   or structure that is connected to the earth by one or more of the following   
   methods: (1) At least one structural metal member that is in direct contact   
   with the earth for 3.0 m    
   (10 ft) or mor e, with or without concrete encasement.   
   (2) Hold-down bolts securing the structural steel column that are connected to   
   a concrete-encased electrode that complies with 250.52(A)(3) and is located in   
   the support footing or foundation. The hold-down bolts shall be connected to   
   the concrete-   
   encased electrode by welding, exothermic welding, the usual steel tie wires,   
   or other approved means.     
   (3) Concrete-Encased Electrode. A concrete-encased electrode shall consist of   
   at least 6.0 m (20 ft) of either (1) or (2):   
   (1) One or more bare or zinc galvanized or other electrically conductive   
   coated steel reinforcing bars or rods of not less than 13 mm (½ in.) in dia   
   meter, installed in one continuous 6.0 m (20 ft) length, or if in multiple   
   pieces connected together by    
   the usual steel tie wires, exothermic welding, welding, or other effective   
   means to create a 6.0 m (20 ft) or greater length; or   
   (2) Bare copper conductor not smaller than 4 AWG Metallic components shall be   
   encased by at least 50 mm (2 in.) of concrete and shall be located   
   horizontally within that portion of a concrete foundation or footing that is   
   in direct contact with the earth    
   or within vertical foundations or structural components or members that are in   
   direct contact with the earth.  If multiple concrete- encased electrodes are   
   present at a building or structure, it shall be permissible to bond only one   
   into the grounding    
   electrode system.     
   (4) Ground Ring. A ground ring encircling the building or structure, in direct   
   contact with the earth, consisting of at least 6.0 m (20 ft) of bare copper   
   conductor not smaller than 2 AWG.     
   (5) Rod and Pipe Electrodes. Rod and pipe electrodes shall not be less than   
   2.44 m (8 ft) i n length and shall consist of the following materials.   
   (a) Grounding electrodes of pipe or conduit shall not be smaller than metric   
   designator 21 (trade size 3⁄4) and, where of steel, shall have the outer   
   surface galvanized or otherwise metal-coated for corrosion protection.     
   (b) Rod-type grounding electrodes of stainless steel and copper or zinc coated   
   steel shall be at least 15.87 mm (5⁄8 in.) in diameter, unless listed.     
   (6) Other Listed Electrodes. Other listed grounding electrodes shall be   
   permitted.     
   (7) Plate Electrodes. Each plate electrode shall expose not less than 0.186 m2   
   (2 ft2) of surface to exterior soil. Electrodes of bare or conductively coated   
   iron or steel plates shall be at least 6.4 mm (1⁄4 in.) in thickness. Solid,   
   uncoated    
   electrodes of nonferrous metal shall be at least 1.5 mm (0.06 in.) in   
   thickness.     
      
   --    
   Tom Horne   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)