Electrical Bonding of Gas Piping

Deficiency 1: The bonding clamp is listed only for copper pipe, but the gas piping is black steel. The clamp must be listed for the material it connects to. A clamp suitable for steel pipe must be used.

Deficiency 2: The clamp is installed on a union nut. A union nut is not a reliable electrical connection because it can be loosened and may not provide a permanent low‑impedance path. The bonding connection must be made to a solid, permanent part of the piping, not on a union or other removable fitting.

Deficiency 3: The bonding conductor size. The CEC requires that bonding conductors for gas piping be sized according to the rating of the service or the overcurrent device. For a 120/208 V service, the minimum size is typically 6 AWG copper for a 100 A service, but the actual size depends on the service capacity. The setup does not state the service size, but the main bonding jumper is at the service. The bonding conductor for gas piping must be at least the size of the main bonding jumper or the grounding electrode conductor, depending on the code edition. Under CEC Rule 10‑400, the bonding conductor for a metal piping system must be sized per Table 16, and for a 200 A service, 6 AWG may be insufficient; 4 AWG might be required. The gas fitter should verify the service size and use the correct size.

Deficiency 4: The bonding connection must be accessible. The clamp should be accessible for inspection.

Correct method: Use a listed bonding clamp suitable for steel pipe. Connect the bonding conductor to a clean, bare metal surface of the gas piping, not on a union or fitting. The conductor must be sized per CEC Table 16 based on the service rating. The bonding conductor must run to the grounding electrode system or to the service panel's grounding bus. The connection must be made with an irreversible or approved connector. The bonding conductor must be protected from physical damage if necessary. The gas fitter should also ensure that the gas piping is not used as a grounding electrode, but bonding is required. The bonding conductor should be continuous and not spliced except with approved connectors. Finally, the gas fitter should verify that the bonding is done on the building side of the gas meter, not on the utility side, and that the meter is not bypassed.

No, using gas piping as a grounding electrode is strictly prohibited by the CEC and the National Electrical Code (NEC). Gas piping must not be used as a grounding electrode because it is not a reliable grounding path; it can be disconnected or modified, and it may not have sufficient ampacity. The CEC Rule 10‑700 series and Section 10 prohibit using metal piping systems that contain flammable gases as grounding electrodes. The NEC Article 250.52(B) also prohibits using gas piping as a grounding electrode.

In this scenario, the subpanel in the kitchen is using the gas piping as its grounding electrode, which means the subpanel's equipment grounding conductor is connected to the gas piping instead of a proper grounding electrode. This creates a serious hazard: if a fault occurs in the subpanel, the fault current would travel through the gas piping, potentially causing arcing, overheating, or ignition of gas. Additionally, the gas piping may not have a low‑impedance path to ground, so overcurrent devices may not trip properly, leading to electric shock or fire.

The correct approach is to ground the subpanel to the building's grounding electrode system via an equipment grounding conductor run with the feeders, or to a separate grounding electrode if permitted. The gas piping should be bonded, but not used as a grounding electrode. The gas fitter should inform the electrical contractor and the authority having jurisdiction (AHJ) immediately, as this is a code violation and a safety hazard. The bonding of the gas piping should be separate and not serve as the grounding electrode for any equipment.