How to Choose a Multimeter: Measurement Items, Safety Category, Accuracy, Clamp Meter or Handheld, in 4 Stages

To choose a multimeter, first list what you need to measure, then look at how close to the power source the circuit is and whether the matching safety category (CAT) is enough, then look at accuracy and display resolution, and finally decide between a handheld meter and a clamp meter that clamps around the wire to measure current. The safety category has to be looked at for the meter and the test leads together, not just the voltage figure. This article is written for people choosing a meter for maintenance, production lines or equipment sites; it covers handheld meters and clamp meters that measure voltage, current and resistance, and bench meters used in laboratories are out of scope. It is divided into 4 stages:

• Stage ① | Measurement items: AC or DC, voltage or current, and whether resistance, continuity, capacitance or temperature are needed.

• Stage ② | Safety category: how CAT II, CAT III and CAT IV map to your site, and the test leads count too.

• Stage ③ | Accuracy and resolution: how to read accuracy, what the display digits mean, and when True RMS is needed.

• Stage ④ | Clamp meter or handheld: whether to break the circuit to measure current, the current range, AC or AC/DC, test leads and accessories.

This article starts from “you already know you are buying a meter to measure electricity”. Each stage below covers what to do, what public sources say, and what Jiahon can help with; sources, exceptions and this article’s own summary are in the Notes at the end. This is the general case and still depends on the individual case.

Figure 1: The four stages of choosing a multimeter — measurement items, safety category, accuracy and resolution, clamp meter or handheld (schematic, not to scale).

Stage ①: Measurement items — first list what you need to measure

What to do:

• List what is measured on site: AC voltage, DC voltage, AC current, DC current, resistance, continuity (buzzer), diode, capacitance, frequency, temperature. Do not pay extra for a function that is not on the list.

• Think about AC and DC separately: a 24 V DC signal in a control cabinet, the output of a power supply and the AC at an outlet are measured differently and use different ranges (this article’s summary).

• Some meters include temperature (with a thermocouple) or non-contact voltage detection; whether you use them depends on your site (this article’s summary).

What public sources say: A buying guide from an electronic parts distributor says: a meter should be able to measure at least ordinary voltage, continuity, current and resistance; add capacitance, diode, transistor and inductance tests as needed; advanced models also have thermocouple temperature and non-contact voltage detection. The types are general-purpose, handheld, bench, clamp and modular; a clamp meter can measure current in a circuit without breaking it, and a bench meter is used in laboratories and automation systems (Notes table 1).

What Jiahon can help with:

• Hook Meter (Clamp-Type Digital Meter): the page lists two clamp models. One is an AC/DC clamp meter with current and voltage up to 600 A and 600 V, which also measures resistance (4,000 Ω) and frequency; the other is designed for process control loops, can clamp and measure the microamp current of a 4–20 mA loop without breaking the circuit, and also measures temperature (−200 to 1,090 °C) and resistance up to 50 MΩ.

• Hook Meter · Multimeter: the page lists three models. An AC/DC clamp meter (current 42 mA to 999.9 A, voltage 6 to 600 V); a True RMS handheld multimeter (voltage 6 to 1,000 V, current 60 mA to 10 A); and a power clamp meter (shows voltage, current, power and power factor together).

• Measuring Instruments (Multimeters, Infrared Thermometers, Particle Counters, Carbon Monoxide Meters): this is a series page of 15 measuring instruments, three of which are multimeters, each with a one-sentence introduction on the page (digital display, measures voltage, current and resistance; more measuring functions; economy type). The measuring items and ranges, accuracy and CAT rating of the multimeters are not written on the product page; please inquire. Infrared thermometers and the other instruments are out of scope for this article.

Stage ②: Safety category — how close to the power source the meter can be used

What to do:

• Find out how close to the power source the position you measure is, and match it to a measurement category: outlets and plug-in equipment are CAT II; fixed wiring inside a building, distribution panels, busbars and industrial equipment are CAT III; the service entrance, the electricity meter and the primary overcurrent protection are CAT IV.

• Choose a meter that covers the highest category you may measure, not just the position in front of you this time (this article’s summary). Control cabinets and distribution panels are usually CAT III or above, so confirm before starting (this article’s summary).

• Read the voltage together with the category: “CAT III 600 V” is one set, and the category and the voltage cannot be separated. A bigger voltage figure does not mean safer; for the same position, read the same set of markings.

• Test leads, clips and accessories have ratings of their own, and they should be the same as or higher than the meter’s. Part of the risk of a short circuit or arc is at the lead end; for high-energy industrial circuits, you can also consider fused test leads (this article’s summary).

Figure 2: Measurement categories and positions on site (schematic, not to scale; the category of each position depends on the standard and the meter’s manual).

What public sources say: A public encyclopedia entry sets out the measurement categories of IEC 61010-1: CAT II is equipment connected directly to low-voltage distribution, such as household appliances and portable tools; CAT III is the fixed wiring of a building, including distribution panels, busbars, junction boxes and industrial equipment; CAT IV is the source of a high-voltage distribution installation, such as the electricity meter and the primary overcurrent protection. The table in the entry lists that at a working voltage of 600 V, CAT II, III and IV correspond to transient overvoltages of 4,000 V, 6,000 V and 8,000 V; at 1,000 V they are 6,000 V, 8,000 V and 12,000 V. An application note from a measuring instrument maker (maker’s material) says the voltage marking of a meter does not by itself show safety, because surges can reach several thousand volts; a CAT II 1,000 V meter has to withstand the same impulse as CAT III 600 V, so a high voltage figure does not mean safer; it also points out that the safety of the test leads and probes is at least as important as that of the meter itself. A page from an instrument distributor (with promotion of its own products) says the protection inside a meter cannot stop an arc coming along the line from the probe end, or a short circuit caused by a clamped lead; for high-energy industrial circuits it recommends high rupturing capacity (HRC) fuses (Notes tables 2 and 3).

What Jiahon can help with:

• Hook Meter (Clamp-Type Digital Meter): the product page says the AC/DC clamp model is CAT III 600 V; the process control loop model is CAT III 1,000 V / CAT IV 600 V.

• Hook Meter · Multimeter: the product page says all three models are CAT III 600 V. The handheld multimeter’s voltage measuring range goes up to 1,000 V, yet its CAT rating is written as 600 V: “measuring range” and “CAT rating” are two separate markings, and the latter is the one to look at.

• Measuring Instruments (Multimeters, Infrared Thermometers, Particle Counters, Carbon Monoxide Meters): the CAT rating and certification are not written on the product page; please inquire.

• Multimeter Test Leads: the body of the product page says pure copper wire, low internal resistance and strong insulation, and does not write the CAT category, the rated voltage and current, or whether the leads are fused. The short description at the top of the page lists the wording “1000V”, “20A” and “10A”, with no matching explanation in the body or specifications; which one to take as the reference, please inquire.

Stage ③: Accuracy and resolution — reading the numbers on the specification sheet

What to do:

• Accuracy is often written as “a percentage of the reading plus a number of counts”, for example “0.5% of reading plus 10 counts”. To work it out: multiply the reading by the percentage, then add the number of counts times the size of one step of the scale.

• Resolution is seen from the display digits and counts: 3½ digits is 2,000 counts and 4½ digits is 20,000 counts. More digits make one step of the scale smaller, but accuracy has to be read separately in the specification sheet; more digits does not mean more accurate.

• Read the conditions on the specification sheet: accuracy is usually tied to a particular range, frequency range and temperature (this article’s summary).

• When the site has AC signals that are not sine waves, such as from variable frequency drives and switching power supplies, choose True RMS; a meter marked “average responding” gives errors on non-sinusoidal waves (this article’s summary).

What public sources say: A technical article in the knowledge base of a test instrument maker (2019) gives an example: with the specification “±0.5% of reading plus 10 counts”, on the 5 V range reading 2.0000 V, 0.5% is 10 mV and 10 counts is 1 mV, so the range of the reading is about 1.9890 V to 2.0110 V; it also points out that accuracy is read together with the instrument’s resolution and range. A buying guide from an electronic parts distributor says: digits map to counts as 3½ digits 2,000 counts, 4½ digits 20,000 counts, 5½ digits 200,000 counts; for general work “±3% accuracy is about enough”, while calibrating medical or automotive equipment needs more; a True RMS meter alone can accurately measure both sine and non-sine AC; for pulses or complex signals, look at the crest factor; a meter calibrated at 22 °C and used at 40 °C has a temperature coefficient error. A technical article from a measuring instrument maker (March 2026) also recommends True RMS for professional use (Notes table 4).

What Jiahon can help with:

• Hook Meter (Clamp-Type Digital Meter): the product page says the AC/DC clamp model is True RMS, with a 6,000-count display, auto-ranging, and two AC current ranges, 40 A and 600 A (accuracy ±1.5% to 2.5%); the process control loop model has a 40,000-count display, and the accuracy of its microamp current is ±0.2%. The accuracy of voltage and resistance, and whether the loop model is True RMS, are not written on the product page; please inquire.

• Hook Meter · Multimeter: the product page says the handheld multimeter is True RMS with a 40,000-count display. The accuracy of the three models, whether the other two are True RMS, and the crest factor are not written on the product page; please inquire.

• Measuring Instruments (Multimeters, Infrared Thermometers, Particle Counters, Carbon Monoxide Meters): the accuracy, display digits and whether True RMS of the multimeters are not written on the product page; please inquire.

Stage ④: Clamp meter or handheld — whether to break the circuit to measure current

What to do:

• There are two ways to measure current: a handheld meter puts its leads in series with the circuit, so the circuit has to be broken first; a clamp meter clamps around the wire and the circuit does not have to be broken. To measure current in a running circuit when the current is large, use a clamp meter; for voltage, resistance and continuity, both handheld and clamp meters can do it, but the ranges and resolution of a handheld meter are usually finer (this article’s summary).

• Look at the upper limit of current: the current input of a handheld meter usually has an upper limit, so use a clamp meter where the current is large; the size of the jaw decides how thick a wire it can clamp.

• Look at AC or AC/DC: some clamp meters measure AC alone, so to measure DC (batteries, solar, DC motors) choose a model that measures DC.

• To measure a motor’s starting current, look for an “Inrush” function; where there are variable frequency drives, look for a low-pass filter; where wires are bundled tightly and false voltages are easily picked up, look for a low-impedance (LoZ) mode.

• Test leads, clips, extension leads and other accessories should match the safety category of the meter, and the insulation should be checked for damage first (this article’s summary).

What public sources say: A public article from a thermal imaging and measuring instrument maker (2022) says: a meter measuring current through test leads reaches about 10 A at most, while a clamp meter can measure up to 3,000 A; the larger the jaw, the thicker the wire it can clamp; some clamp meters measure AC and some measure DC, and advanced models measure both; a True RMS clamp meter stays accurate when the waveform is not a sine wave; the inrush mode captures the current at the moment equipment starts; the LoZ mode avoids misreadings caused by “ghost voltage” induced between wires bundled together; a low-pass filter mode is needed where there are variable frequency drives; some models include a non-contact infrared thermometer or dual thermocouple inputs; some use a flexible loop in place of a rigid jaw, which can wrap into a crowded wire bundle. A technical tip page from another measuring instrument maker (March 2026) says the same, and adds that some advanced clamp meters connect by Bluetooth so that people can read them away from the live equipment (Notes table 5).

What Jiahon can help with:

• Hook Meter (Clamp-Type Digital Meter): the product page says the AC/DC clamp model has a current limit of 600 A and a 37 mm jaw, with high-accuracy small-current (40 A) and starting-current functions; the loop model has a current limit of 999 A plus DC microamps and a 25 mm jaw (a test probe is also included). The low-pass filter and LoZ mode are not written on the product page; please inquire.

• Hook Meter · Multimeter: the product page says the AC/DC clamp model has a current limit of 999.9 A and a 46 mm jaw; the current range of the power clamp meter is listed for AC just (limit 600 A) with a 46 mm jaw, and an optional Bluetooth module can send the data; the handheld multimeter’s current goes up to 10 A. The inrush, filter and LoZ functions are not written on the product page; please inquire.

• Multimeter Test Leads: the product page says 20 mm metal probes and 130 mm break-resistant rubber handles, and mentions preventing oxidation of the “banana plug”. The lead length, the plug dimensions and which meters they can be matched with are not written on the product page; please inquire.

When you need to match a type, please prepare four items first: the items and ranges to measure; the highest-level measuring position on site (and the matching CAT); the accuracy needed and whether there are variable frequency drives; and the size of the current to measure and whether the circuit can be broken. You are welcome to contact Jiahon.

Further reading: Multimeter vs Thermal Camera: What Is the Difference

Notes: Sources and Exceptions

This is for readers who need to check; skipping it does not affect the practice above. Where your site’s safety rules and the manuals of your meters and test leads differ from this article, theirs prevail.

Where each stage comes from

Table 1 | Measurement items and types

Table 2 | Measurement categories and transient overvoltages

Table 3 | Test leads and fuses

Table 4 | Accuracy and resolution

Table 5 | Clamp meter functions

Standards referenced

The standards cited in this article should be taken in the current edition of each issuing body.

• IEC 61010-1 Safety requirements for electrical equipment for measurement, control, and laboratory use — Part 1: General requirements. Issuing body: IEC (International Electrotechnical Commission).

This is the general case and still depends on the individual case.

Exceptions and limits

• What was seen and not seen: this article looked at seven public web pages (see the table above). The full text of IEC 61010-1 was not read; the measurement categories and transient voltage figures are taken from the encyclopedia entry’s account and were cross-checked against two sets of figures in source 4 (CAT II 1,000 V and CAT III 600 V are both about 6 kV; CAT IV 600 V and CAT III 1,000 V are both about 8 kV), with no inconsistency found; the entry cites the 2004 edition of the standard, so for the current edition’s values take the standard itself.

• Sources with a standpoint: source 1 is a distributor’s buying guide, with links to its own and other brands’ products; source 4 is a maker’s application note, with promotion of its own products and unsupported statements, and this article takes just its explanation of CAT and surges; source 7 is a distributor’s page with promotion of its own products, and 30 kA is a figure written on that page, which this article did not confirm independently.

• Inconsistencies inside source pages: the body of source 1 writes 4½ digits as “½ digits”, and this article follows its table; the example in source 6 for a 2.000 V display gives a range that does not agree with its own method of working, and this article does not quote that example’s numbers.

• “One source’s” numbers: the accuracy example, digits-to-counts and the current ranges are examples or one source’s statements, not selection thresholds; “±3% accuracy is about enough” is source 1’s general statement, and this article did not write it as a threshold.

• Years: sources 1, 3 and 4 show no year; source 2 is 2022; source 5 is 2026; source 6 is 2019; the footer of source 7 shows copyright 2026.

• This article’s own summary: the following are this article’s arrangement of the sources, not written that way in the sources: in stage ①, “do not pay extra for a function not on the list”, “AC and DC ranges differ”, “whether temperature and voltage detection are used depends on the site”; in stage ②, “choose a meter that covers the highest category you may measure”, “control cabinets and distribution panels are usually CAT III or above”, “test lead ratings should be the same as or higher than the meter’s”, “for high-energy circuits consider fused test leads” (sources 4 and 7 just say the safety of the leads is important and what the fuse does); in stage ③, “accuracy is tied to range, frequency and temperature”, “a meter marked average responding gives errors on non-sinusoidal waves” (source 1 just says a True RMS meter alone can accurately measure both waveforms); in stage ④, “the ranges and resolution of a handheld meter are usually finer”, “accessory ratings should match the meter and the insulation should be checked for damage first”.

• Scope: this article covers just handheld meters and clamp meters; it does not cover bench meters, calibration, power quality analysis, the working procedure and wiring when measuring, nor price and lead time. For the safety rules of measuring work, follow your site’s rules and the equipment manuals.

• Equipment and products: the figures and wording in “What Jiahon Can Help With” were read from the text of the product pages on October 13, 2026; the product images were not looked at and no manuals were read; they were not verified by this article, and the specification is as on the product page, and for what the product page does not write, please inquire. Where one product page lists several models, this article calls them “one model” and “another model”, and writes no model number or brand. The “selection advice” and “see also” parts of the product pages are the pages’ own marketing wording and were not quoted. Which meter products are on the site was found with the site’s product search; a product search is not a stock inquiry, and for stock please inquire.

This article is a summary for the general case, not a restatement of standard clauses, and not an endorsement of any supplier, equipment maker or service provider, nor an assurance for your equipment and work. Please take your site’s safety rules, the manuals of your meters and test leads, and your own verification as the reference; this is the general case and still depends on the individual case.