Earth loop impedance testers to verify the loop impedance of a live electrical circuit without the need to disconnect the electrical supply. The LTW300 series instruments offer a safe and easy 2 wire loop testing solution that does not trip 30mA RCDs and can be used on a wide range of voltages.

Backlit display
0.01Ω resolution
No-trip loop test on circuits with RCDs of ≥30 mA
3 phase circuits with RCD protection can be tested
Tests radial circuits where the circuit does not return to the origin, even where only a phase and neutral contacts are available.
10 second non trip loop test time with Auto test extension up to a further 10 seconds if noise is detected, to improve the accuracy of the test
High current loop testing for supplies that do not have an RCD fitted
AUTO START will start the loop test running as soon as the test leads are connected; no need to press the test button means much safer testing
PFC Display up to 20kA
Voltage and frequency measurement
110Vac systems including 110V centre tap to earth (55V phase to earth) can be tested on the secondary winding.
IP54 Weatherproof case
Optional 10A fused 2 wired test leads and crocodile clip set
Complies with IEC61010-1 300V CATIV safety standard and meets EN61557

RS is an authorised Megger distributor. Purchased though RS this product is eligible for the Megger extended 3 Year warranty

Test lead set with crocodile clips, mains socket test lead, 8 AA alkaline batteries, hard carry case and instructions.

Need to confirm the effectiveness of a fuse or circuit breaker? Choose this Megger loop impedance tester. By attaching its leads to your test equipment, you can determine whether your protective device will be triggered in the event of a fault of up to 20kA. This product has a wide operating temperature range between -10°C and +50°C, so it can handle the heat in harsh work areas. A backlit display means you're not left in the dark when viewing results in dimly lit environments.

• Carry case has an IP54 rating, so it's protected against limited amounts of dust and water sprays
• High accuracy of ±5% at 230V AC for precise results
• Battery life allows for 2000 consecutive tests for long-lasting performance
• Auto-start function for safe and contact-free testing

• Circuit breakers
• Electrical installations
• Distribution boards
• Power generation

It has a wide operating voltage range of 100 to 280V, so it's a versatile choice for use in low-power systems.