Fluke 324 Clamp Meter: Specs, CAT Ratings and What to Check

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The Fluke 324 is a true-RMS clamp meter for AC current, voltage, resistance, continuity, capacitance and contact temperature. This guide sets out the figures Fluke publishes for the 324, explains what its safety ratings mean, and lists what to check before you rely on one. Fluke marks the 324 as discontinued or reclassified, so check the manual for your own unit.

Quick answer

The Fluke 324 measures AC current up to 400.0 A, AC and DC voltage up to 600.0 V, resistance, continuity, capacitance and contact temperature, according to Fluke’s product page.
Fluke lists CAT III 600 V and CAT IV 300 V as the safety ratings. Use the category that matches the circuit you are working on.
The page lists no DC current measurement for this model. If you need DC amps, the 324 is the wrong meter.
Fluke marks the product as discontinued and suggests the Fluke 325.

What the Fluke 324 measures

A clamp meter measures current without breaking the circuit. The jaw closes around one conductor, and the meter reads the magnetic field that the current creates. That is why a clamp is faster than a series meter when you need to check a live load, a motor feed or a branch circuit. The 324 uses that method for AC current only.

According to Fluke’s product page, the AC current range is 40.00 A and 400.0 A. The stated accuracy is 1.5% plus 5 digits across 45 Hz to 400 Hz, and the page adds 2% for position sensitivity. Those two figures matter in practice. The position error means that the reading can shift a little depending on where the conductor sits inside the jaw, so center the wire and keep it perpendicular to the jaw where you can.

The voltage functions cover AC and DC up to 600.0 V. Fluke lists AC voltage accuracy at 1.5% plus 5 digits and DC voltage accuracy at 1.0% plus 5 digits. Resistance is listed with two ranges, 400.0 ohms and 4000 ohms, at 1.0% plus 5 digits. Continuity is listed at 30 ohms or less, which is the usual threshold for an audible or visual continuity check.

Capacitance is listed in two spans: 0 to 100.0 microfarads and 100 microfarads to 1000 microfarads. Contact temperature is listed from -10.0 degrees C to 400.0 degrees C, which is 14.0 degrees F to 752.0 degrees F. Contact temperature means you touch the probe to the surface being measured, so it is useful for checking a motor housing or a bearing, not for reading the air in a room.

Published specifications

The table below lists the figures that appear on Fluke’s product page for the 324. Where the page shows a dash, the function is not offered.

AC current: 40.00 A / 400.0 A, 1.5% plus 5 digits (45 Hz to 400 Hz), plus 2% for position sensitivity.
DC current: not offered on this model.
AC voltage: 600.0 V, 1.5% plus 5 digits.
DC voltage: 600.0 V, 1.0% plus 5 digits.
Resistance: 400.0 ohms / 4000 ohms, 1.0% plus 5 digits.
Continuity: 30 ohms or less.
Capacitance: 0 to 100.0 microfarads / 100 microfarads to 1000 microfarads.
Temperature (contact): -10.0 degrees C to 400.0 degrees C.
Safety rating: CAT III 600 V and CAT IV 300 V.
Maximum wire diameter: 30 mm (600 MCM).
Size: 207 x 75 x 34 mm.
Weight: 208 g.
Power: two AAA batteries, installed.
Warranty: two years.

The page does not state a fuse rating, and it does not give a frequency range for the voltage function. Do not assume either figure. If you need one of them for a procedure or a report, look for it in the manual for your unit.

What the CAT ratings mean

The CAT rating is the part of a meter’s specification that people most often misread. It is not only a voltage number. Fluke’s guidance on CAT ratings explains that the category describes the electrical environment where the meter may be used. Category III covers fixed installations inside a building, such as switchgear, polyphase motors and permanently wired equipment. Category IV covers the origin of the installation, where low-voltage wiring connects to the utility supply.

Fluke’s advice is to choose a meter rated for the highest category you could be working in. For the 324, that means CAT III 600 V for most building work and CAT IV 300 V for work at the service entrance. The category and the voltage together set the limit. A 600 V CAT III rating does not mean the meter is safe on a 600 V CAT IV circuit, and the CAT IV rating is lower in voltage terms because the risk comes from fault current at the point where the supply enters the building.

Your test leads also need to meet the category you work in. The meter rating does not extend to leads with a lower rating. Check the lead ratings before you start, replace leads with cracked insulation, and keep your fingers behind the finger guards when you clamp a live conductor. These steps are basic, and they matter more than any single number on the spec page.

How to use the clamp safely

Start with the function selector set to the measurement you need. Confirm the range before you close the jaw, because switching ranges with the jaw around a live conductor is a common way to get a misleading reading. Close the jaw fully. A jaw that is not seated can give a low reading, and the position error means small changes in where the conductor sits can change the result.

For voltage, connect the leads to the meter before you touch the circuit, and use the probe tips rated for the category you are working in. Check the meter on a known source before and after a job if you can. For resistance and continuity, the circuit must be de-energized. Never measure resistance on a live circuit.

For contact temperature, use the probe on a clean surface and wait for the reading to settle. Surface temperature of a motor or pipe is not the same as the temperature of the fluid or air inside it, so label the reading as surface temperature in your notes.

What to check before you buy or use one

Because Fluke lists the 324 as discontinued, check three things before you buy a used unit or rely on an older one.

First, confirm the model number on the meter body. The 323, 324 and 325 look similar, and the functions differ. The product page lists no DC current function for the 324. If you need DC amps, do not buy a 324 for that work, and check the function list of any other model before you buy it.

Second, check the batteries and the compartment. The product page lists two AAA batteries. Replace them with fresh cells, and check the battery door and contacts for corrosion before you trust a reading. A weak battery can make a meter behave oddly, and a damaged battery contact is a common fault on older clamp meters.

Third, check the case and leads. A cracked case or worn lead insulation is a reason to stop using the meter until it is repaired or replaced. Fluke’s published warranty for the 324 is two years, which applies to new units under the original terms. For a used meter, the warranty status depends on the seller and the purchase date, so ask for the purchase record if you need one.

Where the 324 fits

The 324 suits a technician who needs AC current, voltage, resistance and temperature in one clamp, and who works mainly on AC circuits. It is a practical choice for building maintenance, HVAC and light industrial checks where the main task is reading load current. It is less suitable where you need DC current, where you need a rating above CAT IV 300 V at the service entrance, or where you want a current model that Fluke still sells.

If you are comparing the 324 with a newer Fluke model, look at the current-measurement range, the DC functions, the safety category and the warranty period side by side. Use the figures printed on the current product page, not on a retailer summary, and confirm them against the manual for the exact model you plan to buy.

How we chose these figures

Every figure in this guide comes from the Fluke product pages for the 324 listed in the sources below. We did not use retailer listings, distributor tables, third-party manual hosts or forum posts for any specification. Where two Fluke pages gave the same figure, we kept it; where a figure appeared on only one page, we say so in the text. The CAT explanation comes from Fluke’s own guidance on measurement categories.

What we could not verify

We could not open an official Fluke PDF manual for the 324 from an allowed source, so the fuse rating, the frequency range for voltage and the full accuracy notes for capacitance and temperature are not stated here. Earlier search results pointed to third-party manual hosts; we did not open or rely on them. Check the manual that came with your meter for those details.

Frequently asked questions

Does the Fluke 324 measure DC current?

No. The 324 is an AC current meter, with ranges of 40.00 A and 400.0 A.

Is the Fluke 324 CAT IV rated?

Fluke lists CAT IV 300 V for the 324, and CAT III 600 V. Use the category that matches the point where you are working.

Is the Fluke 324 still sold new?

Fluke’s product page marks it as discontinued or reclassified and suggests the Fluke 325. Check current stock with a seller before you plan a purchase.

For a wider view of clamp meters from the same maker, see our guide to Fluke clamp meters for automotive work and the Fluke multimeter lineup.

Summary

The Fluke 324 is a true-RMS clamp meter with AC current to 400.0 A, AC and DC voltage to 600.0 V, resistance, continuity, capacitance and contact temperature. Fluke lists CAT III 600 V and CAT IV 300 V, a two-year warranty, and a discontinued status with the 325 suggested as the successor. Check the function list against your task, read the CAT rating against the circuit you will work on, and confirm the figures in the manual for your exact unit before you rely on them.

Sources

Fluke, “Fluke 324 True-RMS Clamp Meter with Temperature & Capacitance”, product page (en-in), https://fluke.com/en-in/product/electrical-testing/clamp-meters/fluke-324 , opened 2026-10-28.
Fluke, “Fluke 324 True-RMS Clamp Meter”, product page (en-us), https://www.fluke.com/en-us/product/electrical-testing/clamp-meters/fluke-324 , opened 2026-10-28.
Fluke, “Why use a CAT III rated meter in solar PV installations?”, https://fluke.com/en-in/learn/blog/renewable-energy/cat3-clamp-meter , opened 2026-10-28.