What must be done before performing maintenance on LP gas equipment?

Before performing maintenance on LP gas equipment, it is essential to turn off the gas supply. This step is critical for safety and prevents the risk of gas leaks or explosions during the maintenance process. By ensuring that the gas supply is shut off, technicians can work on the equipment without the danger of gas being released, which could create hazardous situations for both the workers and the environment.

In the context of the other options, while notifying local authorities or draining the tank might be necessary in specific circumstances or regulations, they are not universally required before maintenance. Signing a safety waiver is also not a standard procedure before working on such equipment, as safety measures revolve around ensuring the gas supply is off and adhering to proper maintenance protocols rather than legal formalities.