Built for sparkies and HVAC techs who work in tight switchboards. The Testo 770-1 True RMS Clamp Meter hooks onto single conductors without fumbling, auto-detects AC/DC, and captures starting current—in other words, a real time-saver on installs and fault-finds. If you’re chasing reliable measurements with no fuss, this one’s a ripper
Key Features & Trade Benefits
- Hook clamp with retractable jaw — Feature: one jaw retracts to “hook” a single conductor; Benefit: faster, safer clamping in packed cabinets (less finger gymnastics).
- True RMS accuracy — Feature: TRMS on AC signals; Benefit: trustworthy readings on VFDs and noisy circuits, reducing call-backs.
- Auto AC/DC + auto parameter detection — Feature: meter auto-selects volts, amps, resistance, continuity, diode, capacitance; Benefit: quick testing with fewer dial changes.
- Inrush (starting) current — Feature: captures motor start; Benefit: speeds diagnosis of compressors and fan motors.
- CAT IV 600V / CAT III 1000V — Feature: high safety category; Benefit: confidence on switchboards and mains.
- Large two-line display — Feature: dual readout; Benefit: clearer at a glance, even up a ladder on a hot arvo.
- Compact, 0.1–400 A AC/DC — Feature: broad current range; Benefit: one meter for domestic and light-commercial HVAC/R.
Why This Clamp Meter Matters
Fair dinkum, tight boards are where cheap clamps go to die. The 770-1’s hook clamp lets you snag a single conductor in a tangle, then measure inrush on a split-system compressor without wrestling the panel. It’s ideal for routine maintenance and commissioning—especially when time’s tight and the client’s watching. For more options, see our Clamp Meter Collection.
Pro Tip
When checking inrush on condenser fan motors, zero the meter first and centre the conductor in the jaw. Take two captures a few seconds apart—if the second spike is way higher, you might be chasing a sticky start capacitor (no worries, this meter will show it).
Compatibility & System Info
- Works across HVAC/R systems: split systems, ducted, package units, VRF/VRV, heat pumps.
- Refrigeration jobs: measure compressor draw vs nameplate to confirm charge or mechanical issues.
- Electrical categories: CAT IV 600V / CAT III 1000V per EN 61010-2-032; EMC per EN 61326-1.
- Ideal for Aussie conditions: great for Sydney rooftops in summer and Brisbane plantrooms where humidity cooks lesser tools.
What’s Included
- Testo 770-1 True RMS Clamp Meter
- Test leads (1 set)
- 3 × AAA batteries
- Quick start/Instruction manual
- Certificate of conformity
Specifications
| Parameter | 770-1 | 770-2 | 770-3 |
|---|---|---|---|
| True RMS | Yes | Yes | Yes |
| Voltage range | 1 mV – 600 V AC/DC | 1 mV – 600 V AC/DC | 1 mV – 600 V AC/DC |
| Current range (jaws) | 0.1 – 400 A AC/DC | 0.1 – 400 A AC/DC | 0.1 – 600 A AC/DC |
| μA range (leads) | – | 0.1 – 400 μA AC/DC | 0.1 – 600 μA AC/DC |
| Resistance | 0.1 Ω – 40 MΩ | 0.1 Ω – 40 MΩ | 0.1 Ω – 60 MΩ |
| Frequency | 0.001 Hz – 10 kHz | 0.001 Hz – 10 kHz | 0.001 Hz – 10 kHz |
| Capacitance | 0.001 μF – 100 μF | 0.001 μF – 100 μF | 0.001 μF – 60,000 μF |
| Temperature | – | –20 to +500 °C (adapter) | –20 to +500 °C (adapter) |
| Display count | 4,000 | 4,000 | 6,000 |
| Safety category | CAT IV 600 V / CAT III 1000 V | ||
| Operating temp | –10 to +50 °C | ||
| Dimensions (L×W×H) | ≈ 243 × 96 × 43 mm | ||
| Weight | ≈ 378 g | ||
| Standards | EN 61326-1; EN 61010-2-032; DIN EN 61140 | ||
Warranty & Returns
Backed by a 2-year Testo warranty. See our store Returns Policy for change-of-mind or DOA procedures. Instruments should be used by trained personnel and operated per the manual (safety categories apply).
FAQs
The 770-1 does not include a μA range. If you need μA and a K-type temperature adapter, step up to the Testo 770-2.
770-3 adds 600 A jaws, power (W/PF) measurement and Bluetooth App connectivity. See Testo 770-3.
Yes—rated CAT IV 600V / CAT III 1000V. Always follow isolation procedures and the instrument manual.
We’ve got a short explainer here: What is a Clamp Meter?
Related Products (hand-picked)
- Uni-T UTL27 CAT IV Test Probes — handy spares with removable tip shields for tight panels.
- Testo 770-2 Clamp Meter — adds μA + K-type adapter for gas/flame sensing.
- Testo 770-3 Clamp Meter — power measurement + Bluetooth App for trend logging.
- Instrument Cases & Bags — keep your meter protected between jobs.
Authoritative Reference
See the official Testo 770-1 page for manufacturer specs and manuals.