Fieldpiece Lt17a

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The Fieldpiece LT17A is a manual-ranging, classic-style digital multimeter aimed at HVAC/R technicians. It measures AC and DC voltage, AC and DC current, resistance, capacitance, frequency, continuity, diode, and temperature with a K-type thermocouple input. It also works with Fieldpiece accessory heads and can be paired with the ACH4 AC clamp. This guide explains what the meter does, what its published ranges and accuracy are, how the clamp fits in, and where the manufacturer’s own documents disagree, so you can judge whether the LT17A fits your work.

Quick answer

The Fieldpiece LT17A is a manual-ranging HVAC/R multimeter with a K-type temperature input and an optional 400 A AC clamp. Its published ranges cover AC/DC voltage up to 600 V, resistance up to 20 M ohm, and temperature from -30 to 1400 degrees F. Fieldpiece’s documents disagree on the top capacitance range and on whether the clamp is included, so confirm both on the box or listing.

How we chose these sources

We opened three Fieldpiece and TestEquity documents and read the specification tables directly from the PDFs. The operator’s manual, version 13, is the most recent document we could open, so we treated its tables as the primary reference and noted each place where an older copy differs.

What the Fieldpiece LT17A is built for

The LT17A is designed around HVAC/R tasks rather than general electronics. Fieldpiece describes it as a classic-style manual-ranging meter, meaning you pick the function and range yourself with a rotary dial instead of letting the meter choose. The body is ABS plastic with a blue backlight, and the test leads store inside the meter body. The manual says the meter is rated to IEC 61010-1 (EN 61010-1), CAT III 600 V, Class II, pollution degree 2, for indoor use.

The main reason technicians buy this type of meter is the temperature function. The LT17A reads temperature from -30 to 1400 degrees F (-34 to 760 degrees C) with a K-type thermocouple, which covers supply and return air checks, line temperatures, and flue readings. The meter also has a field calibration adjustment: the manual describes checking against an ice-water bath at 32 degrees F (0 degrees C) and using the TEMP OFFSET control to bring the reading to 32.0.

Measurement ranges and accuracy

The figures below come from the operator’s manual, version 13. Read them as the manufacturer’s stated limits, not as a guarantee for a particular unit.

• DC voltage: 200 mV, 2000 mV, 20 V, 200 V, 600 V. Stated accuracy 0.5% reading plus 1 digit. Input impedance 10 M ohm.
• AC voltage (50 Hz to 500 Hz): the same five ranges. Stated accuracy 1.2% plus 4 digits on the 200 mV to 20 V ranges, and 2% plus 4 digits on the 200 V and 600 V ranges.
• DC current: a microamp range, 20 mA, and 200 mA. Stated accuracy 1.0% plus 1 digit. The extracted text drops the micro symbol, so confirm the microamp label on the meter’s dial before relying on that range.
• AC current: the same range set, with stated accuracy 1.5% plus 4 digits. The meter’s own inputs are not a clamp; the clamp is a separate accessory.
• Resistance: 200 ohm, 2 k ohm, 200 k ohm, 20 M ohm. Stated accuracy 1.0% plus 4 digits on the 200 ohm to 200 k ohm ranges, and 2.0% plus 4 digits on the 20 M ohm range. Open-circuit voltage is about 0.3 V DC.
• Continuity and diode: an audible continuity beeper that sounds below about 100 ohm, and a diode test with about 1 mA test current and about 3 V open-circuit voltage.
• Capacitance: the manual lists three ranges, 200 uF, 2 kuF and 20 kuF in its own notation, with stated accuracy 4% plus 10 digits. This is where the documents disagree (see below).
• Frequency: 10 Hz to 40 kHz, resolution 1 Hz, stated accuracy 0.1% plus 3 digits, with a sensitivity of 3.5 V RMS minimum.
• Temperature: -30 to 1400 degrees F. Stated accuracy plus or minus 1 degree F from 32 to 120 degrees F, and wider tolerances outside that band.

Where the documents disagree

Fieldpiece’s own materials do not agree on every number. The current manual lists AC and DC current ranges and a capacitance set that differ from the older datasheet. The 2007 datasheet we opened lists AC current ranges of 200, 2k and 20k, and a capacitance range of 400. The product sheet we opened says the meter measures capacitance up to 200 MFD. Because the manual is the most recent document we could open, this guide follows it, but the meter’s dial and the box label are the final check.

The ACH4 clamp and the 400 AAC claim

The LT17A’s headline number is 400 AAC, which refers to the optional ACH4 clamp rather than to the meter’s own current jacks. The clamp is rated 400 A AC maximum and carries a CAT III 300 V marking on its label. Its output is a millivolt signal, so you set the meter to AC millivolts to read it. The manual says the clamp’s scale is 1 mV AC per amp on the low range, and the meter should be set to read AC millivolts when the clamp is in use.

Whether the clamp is in the box is another point where the documents differ. The 2007 datasheet and the product sheet describe the meter as “with included clamp” and “400 AAC with included clamp.” The operator’s manual says the ACH4 is sold separately. Before you buy, check the listing or invoice for the clamp, and do not assume it is included.

Fieldpiece’s accessory heads, such as the ARH4 for air velocity and temperature and the AAV3 for air velocity, convert their own measurements into a millivolt signal that the LT17A reads in DC millivolts. The manual says any meter with these millivolt scales can use the accessory heads, but the LT17A is the one designed around them.

Leads, power and maintenance

The manual recommends Fieldpiece’s deluxe silicone test leads, model ADLS2, which have removable probe tips. Those tips are needed to attach accessory heads. The meter runs on one 9 V battery, type 1604, and the manual gives a typical battery life of about 150 hours. The meter shows a low-battery indicator and turns itself off after 25 minutes of inactivity.

The fuses are 0.25 A, 500 V, 6.3 by 32 mm, model RFM66. The manual says replace them only using the overload protection chart inside the case, and that any other repair should go to a Fieldpiece service center. Operating environment is 32 to 122 degrees F (0 to 50 degrees C) below 70 percent relative humidity, and storage is -4 to 140 degrees F (-20 to 60 degrees C).

Who the LT17A suits

The LT17A makes sense for a technician who wants a manual-ranging meter with a built-in K-type temperature input, a continuity beeper, and the option of Fieldpiece accessory heads. It is not a true-RMS, auto-ranging meter, and the manual does not list a true-RMS function, so do not use it for distorted waveforms without checking your task. If you mostly need general voltage and resistance checks with automatic range selection, a lower-cost auto-ranging meter may be a simpler choice. For a broader comparison of meter types, see our guide to the best hand-held digital multimeters.

If you need a clamp for current work and plan to use the clamp more than the meter’s own inputs, look at a clamp meter with its own display. Our guide to the best true-RMS digital clamp meters covers that category and explains the difference between true-RMS and average-responding readings.

What we could not verify

We could not verify the LT17A’s real-world accuracy against a calibrated reference, because we had no unit to test. We also did not open an independent third-party teardown or a Fieldpiece calibration certificate, so the accuracy figures above are the manufacturer’s stated figures only. The current capacitance top range and the clamp inclusion disagree across Fieldpiece’s documents, and we could not settle either point from the sources available to us. Check your own unit’s label and the seller’s listing before you rely on those details.

FAQ

Is the Fieldpiece LT17A a true-RMS meter?

The manuals we opened do not list a true-RMS function for the LT17A. Treat it as a standard AC meter and check the manual or meter label before using it on non-sinusoidal loads.

Does the LT17A measure temperature?

Yes. It reads -30 to 1400 degrees F with a K-type thermocouple, and the manual describes a field offset adjustment using an ice-water bath.

Is the 400 A clamp included with the LT17A?

The operator’s manual says the ACH4 clamp is sold separately, while the product sheet and 2007 datasheet describe the clamp as included. Check the listing or invoice before buying.

What battery does the LT17A use?

One 9 V battery, type 1604. The manual gives a typical life of about 150 hours.

What fuse does the LT17A use?

The manual lists a 0.25 A, 500 V, 6.3 by 32 mm fuse, model RFM66, for the protected ranges.

Sources

• Fieldpiece Instruments, LT17A Digital Multimeter operator’s manual, version 13: https://resources.fieldpiece.com/wp-content/uploads/2020/11/Opman-LT17A-v13_ESM.pdf (opened 2026-10-29)
• Fieldpiece Instruments, LT17A product sheet: https://resources.fieldpiece.com/wp-content/uploads/2020/11/LT17A-02.pdf (opened 2026-10-29)
• TestEquity, Fieldpiece LT17A Digital Multimeter datasheet (2007 copy): https://assets.testequity.com/te1/Documents/pdf/Fieldpiece/Fieldpiece_LT17A_Digital-Multimeter_Datasheet.pdf (opened 2026-10-29)