Fluke ST120 GFCI Socket Tester
August 1, 2025
The Fluke ST120 GFCI Socket Tester checks that each wire in the outlet is properly connected to the building’s electrical system. Via the bright LEDs and included chart, you can quickly and easily verify the wiring of an outlet. Able to identify several common wiring errors, including reversed phase and neutral wires and an open ground, the ST120 will give you confidence on your next job.
- Simple operation – Plug into socket; with the bright, easy-to-see LEDs, verify correct wiring or identify common wiring problems in both standard and GFCI outlets
- Know more, faster –with the handy chart, quickly identify one of six wiring conditions for the outlet
- GFCI outlets–with an integrated GFCI test, you can feel secure knowing that your GFCI equipped outlets are functioning properly
One-button GFCI tests
The included GFCI test button on the ST120 Socket Tester allows you to also test the operation of GFCI outlets. With a single push, the ST120 can verify the operation of your GFCI equipped outlet. If the GFCI trips as expected, perfect, you can move on. If not, it’s time to take a closer look.
Fast visual identification of all 6 wiring conditions
The ST120 has three bright, easy-to-see LED indicators. This lets you see, at a glance, one of six wiring scenarios:
- Correct installation
- Open ground
- Open neutral
- Open hot
- Hot/neutral reversed
- Hot/ground reversed
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