Purpose

Before continuing with diagnostics, confirm that power is reaching the fixture.
Use the procedure below to verify isolation transformer output/fixture input current.

Tools Required

Clamp meter (True RMS, rated for airfield current levels).

Procedure

Locate the fixture’s pigtail cable — it connects to the transformer’s 2-prong female secondary.
Identify the two conductors leading into the molded plug.
Clamp your AC meter around one conductor only, not both.
Choose the straightest section of wire near the plug for best accuracy.
Power on the Constant Current Regulator (CCR) and set it to a known step, such as 6.6 A.
Observe the clamp meter reading.

Important Information

Clamp only one conductor to prevent phase cancellation.
Never attempt clamp tests on molded connectors where conductors are inaccessible.

Expected Result

The clamp meter reading should match the CCR output current setting.

Safety Reminder

Always maintain safe working conditions by using appropriate personal protective equipment (PPE) where necessary.
Only qualified service personnel should perform current measurements on airfield lighting circuits.

Airport Lighting Company | Troubleshooting Instruction