Types of clamp meters

Clamp meters, known traditionally as clamp-on ammeters, sometimes even as tong testers, fall into three types or categories:

• Current transformer (ac) clamp meters.
• Hall Effect (ac and dc) clamp meters.
• Flexible (ac) clamp meters.

While different, they share the same fundamental methodology when making measurements: A conductor is passed through a probe (either the hard jaws built into a clamp meter, or the flexible coil of a clamp accessory), and the vector sum of the currents flowing through the conductor is calculated by the meter.

Other specialty tools are associated with the clamp meter category. Fluke’s product line addresses a variety of specific troubleshooting issues with clamp-based tools. Some examples:

• Basic electrical testing (example: Fluke T5-1000)
• HVAC (Fluke 902 True-RMS HVAC Clamp Meter)
• Accessory current clamps; plug-in clamps typically used with digital multimeters (Fluke i410 ac/dc Current Clamp)
• Current leakage (Fluke 360 ac Leakage Current Clamp Meter)
• Earth ground testing (Fluke 1630 Earth Ground Clamp Meter)
• Process; for measuring 4-20 mA signals and others (Fluke 773 Milliamp Process Clamp Meter)
• Power quality (Fluke 345 Power Quality Clamp Meter)
• High current (Fluke 355 True-RMS 2000 A Clamp Meter)