Ermenrich Zing ST40 socket tester with Euro plug and button for testing RCD (residual current device) performance. The tester indicates the result with three LEDs after being inserted into the socket. The light signal codes (there are seven in total) can be found directly on the frame of the device: everything is fine; no grounding; there is no zero; missing phase; phase/earth swapped; phase/zero swapped; phase/ground swapped and ground missing.

The tester is also the perfect solution for checking electrical installation work on construction sites and assessing the condition of sockets at home. The device displays the measured voltage on the built-in, backlit screen. It does not require additional power supply.

Main characteristics:

- Voltage measurement, the result is displayed on the built-in screen
- There are 7 ways to test the proper connection of sockets
- Separate button for RCD testing

- AC voltage measurement range 48–250V
- Frequency range, Hz 45–65
- Overvoltage category CAT II 300 V
- Screen yes
- Display backlight ✓
- RCD test (RCD) breaking current >30 mA
- Safety standards EN61010-1-2-030, EN61326-1