(4) Bonding Conductive Materials to an Effective Ground-Fault Current Path. To remove dangerous voltage from ground faults, electrically conductive metal water piping systems, metal sprinkler piping, metal gas piping, and other metal-piping systems, as well as exposed structural steel members that are likely to become energized, must be bonded to an effective ground-fault current path. Figure Above
Author’s Comment: The phrase “likely to become energized” is subject to interpretation by the authority having jurisdiction.
(5) Effective Ground-Fault Current Path. Metal raceways, cables, enclosures, and equipment, as well as other electrically conductive materials that are likely to become energized, must be installed in a manner that creates a permanent, low-impedance fault-current path that facilitates the operation of the circuit overcurrent device. Figure 250–22
Author’s Comment: To assure a low-impedance ground-fault current path, all circuit conductors must be grouped together in the same raceway, cable, or trench [300.3(B), 300.5(I), and 300.20(A)]. Figure 250–23The earth is not considered an effective ground-fault current path.
Ok…now from my portions of this educational moment on grounding the gas piping as shown above.
Lets examine Art 250.104(B)- Other Metal Piping
Ok I will try to break this down because I have had alot of e-mails on this question…Q: Do you bond the gas piping within the dwelling to the GEC and so on…ok…I will answer this under the eyes of the 2002 NEC.
Other Metal Piping Systems- Metal piping systems , such as gas or air piping which may become energized, SHALL BE bonded to the service equipment enclosure, the grounded ( neutral ) service conductor, or the grounding electrode or grounding electrode conductor where the grounding electrode is of sufficient size. The bonding jumper SHALL BE sized in accordance with Table 250.122 using the rating of the circuit that may be energize the piping. The equipment grounding ( bonding ) conductor for the circuit that may be energized the piping can serve as the bonding means.
Ok…translation- The equipment grounding ( bonding ) conductor for the circuit that may energize the piping can serve as the bonding means.
Practicle Translation…If you have a Gas cook top that has a 15A ignitor to the applicance…Do you have to BOND the gas line to it because it is likely to be energized…well YES in theory…but this is taken care of for you in the appliance itself…and completes the requirement…
Now…with that said…Remember this is looked differently at in many AHJ’s but the NEC is clear on it’s wishes…any piping even GAS lines that may become energized need to be bonded to…now here is the question…Who determines which is likely to become energized… Ponder that and hope you enjoyed this Bonding Minute…
If you learn anything from this…remember the EGC of the equipment the piping is run to…can function as the bond…