Mains voltage test: (dead test)

This test isolates the power supply serving the boiler, so as safe, further testing can be continued, without the risk from stray electrical currents causing a shock.

• Electrically isolate power supply at fused spur switch and remove fuse (Always ensure the boiler is fused at 3 amps on completion of work)
• Set multimeter to correct voltage scale (above 240V AC) and check L and N at the boiler terminal block

This should read zero volts, the boiler is now safe to work on.