If you observe sparking along the length of the wire rather than at the electrode

set your meter to volts AC

this tool is designed to fit the square valve stems found on both suction and liquid service ports

Dunkirk WBSB Series II

Lochinvar & A.O. Smith 100208634 Ignition Cable If you observe sparking alongWhen the spark ignites and the system fails to fire, the Lochinvar & A. O. Smith 100208634 Ignition Cable is the direct OEM replacement part required to restore circuit continuity between the ignition control board and the burner electrode. This high voltage 7mm silicone ignition wire is engineered to withstand the extreme thermal cycling found in residential and commercial water heater and boiler environments. It serves as an identical replacement