San Francisco County Municipal Code Art. 250 Grounding

250.50 Revise the first paragraph of this section as follows: 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. A concrete encased electrode as defined by 250.52(A)(3) shall be installed at each new building or structure, and for existing buildings or structures when a new or replacement foundation or footing with a perimeter length of 6.0 m (20 ft.) or more is installed in direct contact with the earth. Where none of these electrodes exist, one or more of the grounding electrodes specified in 250.52(A)(4) through (A)(8) shall be installed and used. Exception: Concrete-encased electrodes of existing buildings or structures shall not be required to be part of the grounding electrode system where the steel reinforcing bars or rods are not accessible for use without disturbing the concrete. 250.64(A) Revise this section as follows: 250.64(A) Aluminum or Copper-Clad Aluminum Conductors. [ ←] Bare aluminum or copper-clad aluminum [ ←] grounding electrode

conductors shall not be used where in direct contact with masonry or the earth or where subject to corrosive conditions. Aluminum or copper-clad aluminum grounding electrode conductors shall not be installed on the outside of a building or structure. 250.64(B) Revise this section as follows: 250.64(B) Securing and Protection Against Physical Damage. Where exposed, a grounding electrode conductor or its enclosure shall be securely fastened to the surface on which it is carried. Grounding electrode conductors shall be permitted to be installed on or through framing members. (1) Not Exposed to Physical Damage. A 6 AWG grounding electrode conductor [ ←] that is free from exposure to physical damage shall be permitted to be run along the surface of the building construction without metal covering or protection. (2) Exposed to Physical Damage. A [ ←] 4 AWG or larger copper [ ←] or aluminum grounding electrode conductor exposed to physical damage shall be protected in rigid metal conduit (RMC), intermediate metal conduit (IMC), [ ←] rigid polyvinyl chloride conduit (PVC), reinforced thermosetting resin conduit Type XW (RTRC-XW), electrical metallic tubing (EMT), or cable armor. Exposed grounding electrode conductors that are accessible to the general public shall be installed in approved metallic raceway. (3) Smaller than 6 AWG. Grounding electrode conductors smaller than 6 AWG shall be protected in RMC, IMC, [ ←] PVC, RTRC-XW, EMT, or cable armor. 6 AWG or smaller grounding electrode conductors shall not be installed exposed below 5 feet. (4) In contact with the Earth. Grounding electrode conductors and grounding electrode bonding jumpers in contact with the earth shall not be required to comply with 300.5, but shall be buried or otherwise protected if subject to physical damage. Chapter 3. Wiring Methods and Materials