Fluke Corporation
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Danger No More: How Fluke Has Reinvented Voltage Measurements

June 10, 2021
In three easy steps, professionals can calculate voltage and current simultaneously all while minimizing the risk of electrical shocks.

Aiming to make electrical testing safer for technicians, Fluke Corporation has developed clamp meters that can measure voltage without any contact with live wires. While there are many non-contact clamp meters on the market, Fluke's is the only one that can make measurements without any test leads—minimizing electrical shock risks while delivering accurate voltage and current values.

New Equipment Digest spoke with Susan Isaac, Product Manager for Fluke Corporation about the 377/378 FC Non-Contact True-RMS AC/DC clamp meters that are saving professionals quality time and increasing their safety in the process.

New Equipment Digest (NED): What are Fluke 377 FC and 378 FC Non-Contact Voltage True-rms AC/DC Clamp Meters and why were they made?

Susan Isaac (SI): The Fluke 377 FC and 378 FC Non-Contact Voltage True-rms AC/DC Clamp Meters are electrical test tools, made for the demanding requirements of industrial electricians. They differ from existing clamp meters in three critical ways: 

  • they allow the user to get an accurate voltage measurement through the clamp jaw; 
  • the voltage measurement can be made without making contact with an electrically live conductor; 
  • the display can show both voltage and current readings simultaneously.

This allows industrial electricians to make critical voltage measurements faster and in a safer manner than currently possible. Since the measurements can be made without touching a live conductor, measurements may be made outside of a distribution panel, which means less time wearing full PPE.

NED: Can you explain how the clamp meters provide a reading without touching live wires? How does this work?

SI: These clamp meters use Fluke’s patented FieldSense technology to measure voltage without test leads. The clamp is connected to any ground point, using the included alligator clip, and generates a reference signal to ground. When clamped around a live conductor, it senses the electrical field generated by the conductor and measures how that field interacts with the reference signal. The voltage is then calculated and shown on the display.

NED: Can you expand on Field-Sense technology? What components make it up and what problem does it aim to solve?

SI: Because FieldSense is patented, Fluke is not at liberty to offer more details on how it works. But we are happy to share what problems it solves:  

  • Safer testing, due to not having to make contact with an energized, metallic conductor.
  • Simpler testing. Measurements can be made at many points along the path of a conductor, meaning there is no longer a need to open a panel or remove wire nuts in a junction box to gain access to a test point.
  • Less time wearing full PPE. Fluke always advises using proper PPE for a given situation. By finding test points outside of a panel, accurate readings can be made in safer situations requiring less PPE.
  • Because FieldSense allows users to make voltage and current measurements simultaneously, it can make complex measurements and calculations far simpler than current methods. 
  • A full set of three-phase measurements, both phase-to-phase, and phase-to-ground, can be made by simply clamping around each phase conductor. This has been shown to save over 50% of the time currently required to take these readings.

NED: What were the forces that lead to the development of these clamp meters and how did the end product measure up to expectations?

SI: First in line is safety, followed by ease of use, and then faster results. All three goals were met. By not needing to work with exposed, energized conductors, electricians can get the answers they need while spending less time in potential arc flash zones. Since both voltage and current measurements can be made by simply clamping around the conductor, the use of the tool has been made simpler. 

In the three-phase example cited above, nine separate measurements were reduced to three, plus all of the math that used to be associated with calculating these results is now done by the clamp and the software in Fluke Connect. Our tests with customers show that the time to make three-phase measurements and calculations was reduced by more than 50%.

NED: What is the current process for taking voltage measurements and how do these clamp meters differ?

SI: Since the beginning of meters and measurements, voltage readings were taken by placing two test leads on two electrically energized conductors. This can be very simple. It can also be very difficult and potentially very dangerous. By eliminating the need to make metallic contact, voltage measurements are simpler, faster, and probably most important, safer.

NED: Can you expand on how users can utilize the stored measurements/data to form a preventative maintenance program? What should they be looking for?

SI: The 377 FC and 378 FC clamps are able to communicate with a smartphone using Fluke Connect software. Readings that are sent from the clamp are stored in the cloud and can be retrieved, reviewed, and graphed. Changes in periodic readings are often indicators of equipment that is on a path toward failure. By spotting these small changes before they become total failures, preventive maintenance can be scheduled for a convenient time. The alternative of “run to failure” leads to catastrophic shutdowns and expensive, unplanned repairs.

NED: Where can these clamp meters be purchased?

SI: The 377 FC and 378 FC clamps are available from leading electrical and industrial distributors globally. Distributors can be found by looking at these products on www.fluke.com. Customers can also purchase these products directly from Fluke, also on Fluke.com.