What defines a ‘cross-connection’ in gas installations?

The definition of a 'cross-connection' in gas installations primarily concerns the potential risks associated with the unintended connection of different systems. In this context, option C refers to an unintentional connection between potable water and gas piping, which poses significant public health and safety concerns.

When potable water is inadvertently connected to gas piping, it can lead to contamination of the water supply. This situation arises if, for example, gas leaks into the potable water system, creating a hazardous environment that can affect both health and safety. Regulatory standards usually enforce the separation of these systems to prevent such occurrences, emphasizing the importance of correct installation practices to ensure that separate utilities do not interconnect in ways that could compromise safety.

In gas installations, maintaining clear boundaries between different systems is essential to mitigate risks and ensure safe and reliable service. The other options, while they may involve connections or separations between utilities, do not accurately capture the essence of a cross-connection as it pertains to gas installations.