250.50 Grounding Electrode System.

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. Wirin Methods and Materials g

ARTICLE 300 – GENERAL REQUIREMENTS FOR WIRING METHODS AND MATERIALS

300.3(C) Revise this section as follows:

300.3(C) Conductors of Different Systems.

(1) 1000 Volts, Nominal or Less. Conductors of acand dc circuits, [ ← ] from separately derived systems, from separate services, or from separate utility meters shall not be permitted to occupy the same equipment wiring enclosure, cable or raceway with conductors from other systems, services, or meters. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway.

Secondary wiring to electric-discharge lamps of 1000 volts or less, if insulated for the secondary voltage involved, shall be permitted to occupy the same luminaire, sign, or outline lighting enclosure as the branch-circuit conductors.

Informational Note No. 1: See 725.136(A) for Class 2 and 3 circuit conductors.

Informational Note No. 2: See 690.4(B) for photovoltaic source and output circuits.

Exception No 1: Photovoltaic Systems: PV Source Circuits and PV Output Circuits in accordance with Section 690.31(B) Identification and Grouping.

Exception No. 2: Emergency Systems: Conductors installed in accordance with Section 700.10 Wiring.

Exception No. 3: Remote-Control, Signaling, and Power-Limited Circuits: Class 1, 2 or 3 Conductors installed in accordance with Article 725.136(A) General.

Exception No. 4: Auxiliary Gutters: When approved by the AHJ Conductors connected to Separately Derived Systems, Service Equipment, or Meter Banks Article 366.

300.4(I) Add the following section:

(I) Subject to Physical Damage. Premises wiring systems installed less than 2.44 m (8 feet) above a walking surface or finished floor are considered subject to physical damage.