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Comparing clamp meters to digital multimeters
Our thanks to Fluke Corporation for allowing us to reprint the following article.
The Fluke 376 clamp meter, left, and the Fluke 87V digital multimeter.
A digital multimeter is essentially a voltage-measuring
tool with some current abilities. A clamp meter is
basically a current-measuring tool with some voltage
abilities. They are distinctly different instruments, each
with its own advantages.
A digital multimeter (DMM) allows you to do electronic
work because it offers high resolution, measuring in
milliunits—millivolts, milliamps and milliohms. It also
allows you to do electrical measurements, though
current is usually limited to less than 20 amps. A digital
multimeter, however, can measure higher currents if a
plug-in clamp accessory is attached.
A clamp meter usually measures to the nearest tenth or
hundredth of a unit, rather than in the milliunits available
with a DMM. This is sufficient for electrical tasks.
Measuring situations
In years past, electricians used test probes rather than a
clamp to measure current. A clamp allows you to
measure current without breaking the circuit and get a
current reading.
In addition, a new generation of clamp meters utilizes
flexible current probes, which Fluke calls iFlex®. These
Rogowski coil probes can squeeze between tightly
packed wires or around large conductors. They can be
handy in a number of situations:

Measuring an analog conveyor speed signal and the
respective motor current simultaneously, so you can
calibrate the system for the required process flow.

Monitoring solenoid output while monitoring input
from the PLC, so you can test the solenoid.

Simultaneously measuring electronic voltages and
electrical currents at a motor drive, to troubleshoot
line speed fluctuations.

Monitoring feeder voltage and current
simultaneously, to troubleshoot nuisance trips.
Simultaneous voltage and current measurements are
part of troubleshooting. Yet you cannot do simultaneous
measurements with one meter unless you step up
several price ranges into equipment used for power
quality work.
1547 N. Trooper Road • P. O. Box 1117 • Worcester, PA 19490-1117 USA
Corporate Phone: 610-825-4990 • Sales: 800-832-4866 or 610-941-2400
Fax: 800-854-8665 or 610-828-5623 • Web: www.techni-tool.com
Effective troubleshooting often requires two meters, one
to measure electrical current and one to measure
voltage. For electricians, a clamp meter is the most
versatile diagnostic tool available. Persons doing
industrial troubleshooting, meanwhile, benefit from a
separate clamp and DMM.

High-end DMM: If your job involves power quality
work. You’ll need the high resolution and advanced
features not found on clamp meters.

Basic clamp meter: If you just need basic current
measurements such as ensuring all three phases on
your feeders are pulling the same current.
A cost-effective approach for many technicians is to buy
one quality instrument designed primarily for voltage (a
DMM) and another tool primarily used for current (a
clamp meter).

Logging clamp meter: If you have intermittent
breaker trips that you need to resolve.

DMM or clamp meter with a detachable display
(which can be separated 30 feet from the body of
the clamp): If you want to take remote readings with
greater safely and without needing a coworker to
assist you.

Advanced clamp meter: If you need to accurately
measure motor inrush current. Also, if you need a
clamp meter with advanced signal processing to
measure the output of a variable frequency drive.
The right combination of test equipment depends on the
equipment you work on and the measurements you
make. With a clamp meter, for example, you might need
a low-pass filter to eliminate electronic interference that
could distort readings.
Here are some general guidelines for deciding which tool
might be right for you:

Basic DMM: If your job requires only basic voltage
and continuity measurements.
1547 N. Trooper Road • P. O. Box 1117 • Worcester, PA 19490-1117 USA
Corporate Phone: 610-825-4990 • Sales: 800-832-4866 or 610-941-2400
Fax: 800-854-8665 or 610-828-5623 • Web: www.techni-tool.com