Under what condition is it permissible to use gas piping as an Electrical Ground?

Using gas piping as an electrical ground is permissible in specific situations where safety and efficacy are ensured, particularly when it is part of the Flame Safeguard Circuit. This context is critical as the Flame Safeguard Circuit is designed to monitor and ensure safe operation of gas appliances, and integrating the electrical grounding in this way can help prevent electrical hazards that may arise from faults within the system. It also allows for the safe dissipation of electrical surges or faults to maintain operational integrity and protect against fire risks associated with ignition sources.

The other conditions listed do not meet the necessary safety standards regarding electrical grounding. For example, gas piping installed underground could be at risk of corrosion, which might create a hazardous situation if used for grounding. Also, if gas piping is isolated from other circuits, this could create a disconnection from the ground reference needed for proper function. Lastly, gas piping painted with non-conductive material would inherently lack the necessary electrical conductivity required for effective grounding, thereby negating any grounding benefits.

Thus, the use of gas piping in a Flame Safeguard Circuit reflects both regulatory standards and safety practices established for gas appliances and electrical systems.