Appliance isolation valves must be installed in the supply line to each appliance,
including portable types. This allows an appliance to be isolated from the main
installation system if it leaks or malfunctions. To ensure that you can easily
control the gas supply to each appliance the valves must be readily accessible.
Boats manufactured before 3 January 2000 are exempt from this part of this
Standard, unless the appliance is connected with a flexible hose.

If there is only one appliance the main shut-off valve is sufficient, unless the
appliance is portable. [7.20]