This Testo 770-2 hook clamp meter is built for HVAC techs who need to quickly troubleshoot electrical faults and take temperature readings. It's especially handy for those hard-to-reach cables on a rooftop unit or in a tight plant room. The unique hook-on jaw lets you grab wires safely without needing a third hand, which can be a lifesaver when you're perched on a ladder.

It goes beyond basic current and voltage, offering microamp measurement for flame sensors and a Type K thermocouple adapter for essential temperature checks on things like flue gases or superheat/subcool lines.

Best For

• HVAC technicians and apprentices
• Electrical diagnostics and troubleshooting
• Flame sensor (ignition flame rod) testing
• Temperature measurement in HVAC systems
• General electrical maintenance and service

Compatibility

The Testo 770-2 handles standard AC and DC electrical measurements up to 600V and current up to 400A. Its integrated Type K thermocouple adapter means it's ready for common Type K temperature probes, expanding its utility for various HVAC tasks. The microamp function is purpose-built for checking the ionisation current on heating system flame rods.

If your job requires specific certifications or higher measurement ranges, always check the full specifications before ordering.

Features

• Unique Hook-On Function: Separates and grabs wires easily without needing to manually open the clamp jaw.
• Retractable Pincer Arm: Makes releasing the hook fast and straightforward, saving time on the job.
• Microamp (µA) Measurement: Essential for accurate flame rod (ignition flame sensor) testing in heating systems.
• Type K Thermocouple Adapter: Allows connection of external Type K probes for precise temperature measurements.
• Automatic Measurement Detection: Identifies the testing in-process and automatically selects the correct meter configuration.
• True RMS (TRMS): Provides accurate readings on distorted waveforms, common in modern electrical systems.
• Starting Current (Inrush) Function: Measures peak current during motor startup.
• Large Two-Line Display: Clearly shows readings for easy interpretation.

Technical Specifications

What's in the Box

• Testo 770-2 hook clamp meter (0590 7702)
• Test leads
• 3 x AAA batteries
• Type K thermocouple adapter
• Instruction manual
• Quick start guide
• Certificate of conformity

Using It on the Job

1. Power Down & Isolate: Always ensure the circuit you're working on is de-energised and locked out before making connections, especially for resistance or continuity tests.
2. Select Function (if needed): While the 770-2 often auto-detects, confirm the correct measurement type (e.g., ACV, DCA, Temp) for critical readings.
3. Clamp for Current: Use the unique hook function to grab a single conductor for non-contact current measurement. For voltage, connect test leads in parallel.
4. Microamp Checks: When testing flame sensors, connect the meter in series with the flame rod and select the µA range to measure ionisation current.
5. Temperature Measurement: Plug your Type K probe into the included adapter and then into the meter to take surface, air, or immersion temperatures.
6. Log Readings: Accurately record all measurements in your service report for diagnostics and compliance.

Limitations & Safety Notes

• Not rated for high-voltage industrial applications beyond 600V.
• Always verify the meter's CAT rating matches or exceeds the circuit being measured.
• Ensure test leads are in excellent condition; replace any damaged or frayed leads immediately.
• Follow all relevant Australian electrical safety standards and Safe Work guidance.
• Only use with specified Type K thermocouples and appropriate accessories for temperature measurements.

When testing flame rods with microamps, make sure your connections are clean. Even a bit of corrosion can skew your readings and lead you down the wrong diagnostic path. Always check both the sensor and the circuit for proper ionisation flow.

Pair With

Pair with a comprehensive electrical toolbox and a set of quality Type K temperature probes for all your diagnostic needs. Check out our range of HVAC test instruments and electrical safety gear.