Klein Tools Multimeter Lineup: 12 Records Sorted by Function

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A search for klein tools multimeter usually means one question: which Klein meter fits the job in front of you? The research file for this keyword holds twelve Klein records, and every one of them is an electrical test tool. Only two are multimeters in their own listing, the MM420 and a digital multimeter kit. The other ten are clamp meters, outlet and receptacle testers, and a circuit breaker and tracing kit. This guide sorts all twelve by what each listing states, flags where a title and its bullets disagree, and sets out the safety lines from the documents we opened.

Quick answer

• The MM420 is the only stand-alone multimeter in this file. Its listing and its instruction sheet both give a 600V voltage ceiling, and the sheet states a CAT III 600V rating.
• The digital multimeter kit names 600V AC and DC voltage and 10A DC current. Its bullets also give a 2 ohm resistance figure that no other Klein meter record in the file gives.
• For clamp work, the CL120 and CL445 read AC current through the jaw, and the CL460S switches between functions without a dial. Choose by the function you need, not by the maker’s name.
• Four of the twelve specification fields carry a CAT figure. Read the category on the record you pick before you use it on a job.

What the twelve Klein records state

The table uses two fields only: the measurement type in the specification block, and any safety figure that appears in that block or in the bullets. A blank cell means neither place gives the item.

Record	Measurement type (specification field)	Safety figure (specification field or bullets)
RT390 circuit analyzer	Voltmeter, Ammeter, Ohmmeter, Time-based	CAT III 135V
CL120KIT clamp meter kit	Not stated	Not stated
Digital multimeter kit with non-contact tester	Multimeter	Not stated
ET450 breaker finder and wire tracer kit	Voltmeter and Frequency Meter	Field reads “[Inferred] Meets Certain Specifications”
CL445 HVAC clamp meter	Voltmeter	CAT IV 600V and CAT III 750V
CL120 clamp meter	Ammeter, Voltmeter, Ohmmeter	Test leads with CAT III and CAT IV caps (bullets)
80025 outlet tester kit	Voltmeter	Not stated
RT110 receptacle tester	Voltmeter	CSA certification, no CAT figure
RT310 AFCI and GFCI tester	Voltmeter	ETL certification, no CAT figure
MM420 multimeter	Multimeter	CAT III 600V
RT210 GFCI outlet tester	Not stated	CAT II 300V
CL460S smart clamp meter	Not stated	Not stated

Four records give a CAT figure in their specification field: the RT390, CL445, MM420 and RT210. The other eight give no CAT figure in that field, so for those records the category is something to confirm on the product’s own documents before a job. This guide cannot supply that figure from the listings alone.

The two multimeters: MM420 and the digital multimeter kit

MM420

The MM420 is the one record in this group that lets us check listing numbers against a manufacturer document. The bullets state AC and DC voltage up to 600V, AC and DC current up to 10A, and 50MΩ resistance. They also list continuity, temperature, capacitance and frequency. Lead-alert LEDs light when the test leads are placed properly. The bullets name a backlit display, and they mention an optional magnetic hanger.

The instruction sheet gives the ranges in printed tables. The DC voltage table runs from 400.0 mV through 4.000 V, 40.00 V and 400.0 V to 600 V. The resistance table starts at 400.0 Ω and ends at 50.0 MΩ. The sheet also states that “The meter defaults to auto-ranging measurement mode,” so the meter sets its own range unless the range button is used to override it.

Two short calculations show what the tables mean in practice. The 600 V range has a 1 V resolution, so 600 divided by 1 is 600 steps across that range. The 50.0 MΩ top resistance range has a 0.1 MΩ resolution, so 50.0 divided by 0.1 is 500 steps. These step counts describe how finely each range reads. They say nothing about accuracy, which the sheet gives on a separate line for each function.

The sheet puts the rating in one line, “Safety Rating: CAT III 600V, Class 2, Double insulation,” and gives the ceiling as “Maximum Input: 600V AC RMS or 600V DC.” The 600 V ceiling also appears under the resistance and capacitance tables, so it applies across those functions. For the current inputs, the sheet lists overload protection as “500mA / 600V and 10A / 600V Fuses.”

The digital multimeter kit

The kit’s bullets say the digital multimeter measures up to 600V AC and DC voltage and 10A DC current. They then give a resistance figure of 2 ohm. That figure is the odd one out in this group. The MM420 and the CL460S state megohm-scale ceilings of 50MΩ and 40MΩ, and no other Klein record gives a 2 ohm value. We could not confirm the 2 ohm line from any document we opened, so treat it as unverified until the kit’s own instruction sheet says the same thing.

The bullets also describe a non-contact tester that covers 12 to 1000 V AC or 70 to 1000 V AC, and a breaker finder that works on 90 to 120 V AC circuits. Those details are useful for a homeowner who wants one kit for several small checks. The bullets give a DC current figure but no AC current figure, so an AC current reading from this kit is not something the listing supports.

Clamp meters: CL120, CL120KIT, CL445 and CL460S

The CL120 is the plainest clamp in the group. Its bullets say it measures AC current through the clamp and reads the non-contact voltage tester inside the jaw. Through the test leads it reads AC and DC voltage, resistance and continuity. It has a backlit display, auto ranging, and an automatic power-off after 10 minutes. Its specification block gives a double insulation safety rating and a CE mark. The bullets name test leads with CAT III and CAT IV safety caps, which is the only category wording in the record.

The CL120KIT is a kit built around the same clamp. Its first set of bullets describes the CL120 functions. Its title adds a GFCI tester, a line splitter, a pouch, leads and three AAA batteries. Its other bullets describe screw cutting and wire stripping for solid and stranded wire from 10 to 20 AWG, which is a hand tool and not a meter. We kept the kit because its first bullets describe a clamp meter. What the kit contains is still an open question, and it is covered in the notes on disagreements and unverified items below.

The CL445 is an HVAC clamp with a 1-1/2-inch jaw. Its bullets list AC current, inrush current and non-contact voltage through the clamp. They also list AC and DC voltage, resistance, continuity, frequency and duty cycle, DC microamps, diode and capacitance. A backlit display shows voltage and current together. The specification block reads Voltmeter as the measurement type, which is narrower than the bullets. Its safety figures are CAT IV 600V and CAT III 750V, the highest category figures in the specification fields of this group.

The CL460S is the smart clamp. Its bullets say it switches between continuity, voltage, current and resistance without a dial. It states AC and DC voltage up to 600V, AC and DC current up to 400A, and 40MΩ resistance. It adds capacitance, frequency, duty cycle and temperature. The record has no measurement-type field, and neither the specification block nor the bullets give a CAT figure. The bullets describe the display as transflective and readable in direct sunlight.

Outlet and receptacle testers: RT110, RT210, RT310, RT390 and 80025

The RT110 is a standard receptacle tester for 110 to 125V AC three-wire outlets. Its light sequence indicates wiring status. The bullets say it conforms to UL Std 1436 and is certified to CSA Std C22.2 #160, and they give an operating range of 0 to 40 C and a 2 m drop rating. The specification block lists the CSA certification and no CAT figure. The RT110 reports wiring problems and gives no voltage reading.

The RT210 is the GFCI version. Its bullets say it verifies the ground fault protective device in GFCI outlets and detects common wiring problems in standard and GFCI receptacles. Its specification block gives CAT II 300V. The bullets do not repeat that figure, so the specification block is the only place it appears.

The RT310 adds AFCI and GFCI testing. Its bullets say it tests AFCI devices by simulating arc fault conditions and tests GFCI devices by simulating ground faults. It also detects a dual-open fault, meaning open neutral and open ground at the same time, using what the bullets call patent-pending technology. Its plug sits on a 10-inch flexible cord that helps reach outlets that are hard to get to. Its specification block shows ETL certification and no CAT figure.

The RT390 is a larger circuit analyzer with a color LCD. Its bullets describe load tests at 12A, 15A and 20A to measure percentage voltage drop, plus AFCI and GFCI trip time and trip current. It has an automatic power-off after five minutes. It is rated CAT III 135V, both in the specification block and in its bullets. That category is far below the 600V CAT III figure on the MM420, so the listing does not support the RT390 for high-voltage work.

The 80025 is a kit with the RT210 GFCI tester and an NCVT1P non-contact voltage tester pen. The bullets describe the pen for detecting voltage in cables, circuit breakers, lighting fixtures and switches. A green LED shows that the tool is running, and a red LED with a warning tone signals detected voltage. The specification block reads Corded Electric as the power source, but the bullets do not say how the pen is powered, so that field needs a check before you buy.

Breaker finding and tracing: ET450

The ET450 is a kit with a transmitter and a receiver. Its bullets describe tracing energized or non-energized breakers, fuses and wires. The receiver sensitivity can be adjusted for tracing through drywall, cement block or shielded cable. The receiver gives an audible beep and visual indicators of signal strength. It has a flashlight and a non-contact voltage function. The transmitter shows external voltage indicators at 12V, 48V, 120V, 240V and 480V.

The specification block reads Voltmeter and Frequency Meter, but it gives no range for either function. Its safety field reads “[Inferred] Meets Certain Specifications,” which is an inferred statement and not a stated certification. A buyer who needs a certified tracing kit should look for that certification on the box or in the manual before relying on this record.

Where a title and its bullets disagree

When a title and its bullets disagree, this guide follows the bullets and says so. The Klein records with a visible conflict are these.

• CL120KIT: the title lists a line splitter, but the bullets describe screw cutting and wire stripping and name no splitter.
• CL445: the specification block reads Voltmeter only, but the bullets list current, resistance, frequency and capacitance.
• 80025: the power-source field reads Corded Electric, while the bullets say nothing about how the NCVT pen is powered.
• Digital multimeter kit: the bullets give a 2 ohm resistance figure, which conflicts with the megohm ceilings in the MM420 and CL460S records. The title gives no resistance figure at all.
• ET450: the safety field reads an inferred statement, not a certification, and the title does not name a safety standard.

Choosing by job

The records group by the job they are built for, and the listing bullets decide which group a record belongs to.

• Outlet and GFCI checks: the RT110 covers standard receptacles, the RT210 covers GFCI outlets, the RT310 adds AFCI and GFCI simulation, and the RT390 adds trip-time and load-test readings. Pick by the device you need to check. The 80025 kit pairs the RT210 with a voltage pen.
• Clamp current readings: the CL120, CL120KIT, CL445 and CL460S read current through the jaw. The CL445 is the one written for HVAC work, with inrush readings and a display that shows voltage and current together.
• Voltage and resistance on one display: the MM420 has the most complete set of printed ranges in this file, with a stated CAT III 600V rating. The digital multimeter kit covers similar functions, but its resistance figure is unconfirmed.
• Tracing a wire or breaker: the ET450 is a tracing kit, and the breaker-finder part of the digital multimeter kit covers breaker location for 90 to 120 V AC circuits.

Safety and the basics the documents support

OSHA’s electrical overview says the agency’s standards are “designed to protect employees exposed to dangers such as electric shock.” The federal work practice rule for electrical work says a “qualified person shall use test equipment to test the circuit elements and electrical parts” of equipment that employees will be exposed to. It also says live parts “shall be deenergized before the employee works on or near them” with exceptions that the rule spells out. Those lines are the regulatory baseline for this guide, and they are the only safety rules we cite here beyond the meter’s own sheet.

Purdue University’s 4-H voltage sheet describes the basic measurement idea. Voltage “can be measured and is the difference between two points,” and it warns that “Working with live electrical circuits can be very hazardous without proper tools and safeguards.” It also states that “the principles for taking measurements are the same” for DC battery circuits and AC house wiring. The principle is the same across both, but the tools and safeguards are not.

The MM420 sheet gives the meter’s own safety instructions, and this guide repeats them without adding steps. It says “Before each use verify meter operation by measuring a known voltage or current.” It says “Do not attempt to measure resistance or continuity on a live circuit.” It says “Use only with CAT III or CAT IV rated test leads.” It also says “Use caution when working with voltages above 25V AC RMS or 60V DC.” The 600V figure is the meter’s maximum input, and the 25V AC and 60V DC line is a far lower caution threshold. Both numbers apply, so a buyer should read the caution line as the stricter of the two. If your work needs a procedure beyond these lines, follow your employer’s written procedure and the instruction sheet for your own meter.

Where to go next

For a non-contact check, the Klein non-contact voltage detector roundup covers Klein non-contact voltage detectors. The Klein Tools voltage detector roundup covers Klein’s voltage detector models. Read the record for the function you need, then compare the stated category before you choose.

How we chose

Every record in the Klein research file went through the same product-type test: a multimeter, clamp meter, voltage or continuity tester, or another electrical test meter. All twelve passed. Nothing in this group is a test-lead kit without a meter, a cable, or a stand-alone hand tool. The CL120KIT contains a hand tool in its other bullets, but its first bullets describe a clamp meter, so the kit stayed in the list with that caveat.

For each record we read the bullets and the specification block. Where a figure appears only in one of them, the text says so. We used the MM420 instruction sheet for the MM420 only, and no other manufacturer document was used for a Klein record. We did not use price, rating or sales data, because the research file does not store them. The order of the picks follows the order of the research file, not any ranking.

What we could not verify

• The documents we opened include one Klein instruction sheet, for the MM420. The ranges and category figures for the other eleven records come from their listing bullets and specification fields only.
• We could not confirm the 2 ohm resistance figure in the digital multimeter kit’s bullets.
• Most listings give no accuracy figure, so this guide does not compare accuracy across the set.
• We could not confirm which items the CL120KIT kit contains, because the title and the bullets name different parts.
• The documents we opened do not cover breaker finders, tracing kits or outlet testers, so the function claims for those records rest on their bullets alone.
• Battery life, weight and warranty terms appear unevenly across the listings, so this guide does not compare them.

FAQ

Is the MM420 the only Klein multimeter in this file?

It is the only record in the file that is a stand-alone multimeter. The digital multimeter kit also states Multimeter as its measurement type, but it is sold with a non-contact tester and breaker-finder parts, so it is a kit rather than a single meter.

Does a Klein clamp meter read voltage as well as current?

Yes, in the bullets of the CL120, CL445 and CL460S. The CL120 reads AC and DC voltage through its test leads, not through the clamp. The CL445 lists AC and DC voltage in its bullets, and the CL460S states AC and DC voltage up to 600V.

Which Klein records give a CAT figure in the specification field?

Four records do: the RT390 with CAT III 135V, the CL445 with CAT IV 600V and CAT III 750V, the MM420 with CAT III 600V, and the RT210 with CAT II 300V. The other eight have no CAT figure in that field.

Can an outlet tester replace a multimeter?

No. The outlet testers in the file report wiring status, GFCI operation or a voltage indication. None of their listings gives a voltage range in the way a multimeter’s tables do, so they answer a different question.

Should I verify the meter before each use?

The MM420 sheet says to do so: “Before each use verify meter operation by measuring a known voltage or current.” Check the instruction sheet for your own meter for its equivalent step. The listings for the other Klein records do not state a verification step.

Bottom line

Choose the record by the function its bullets state, then check the category in the specification field before you use it. For a single meter with a stated CAT III 600V rating and printed ranges, the MM420 is the record in this file with the most figures we could open and check.

Sources

• Electrical (OSHA overview): OSHA’s statement that its electrical standards protect workers from electric shock.
• 29 CFR 1910.333, Selection and use of work practices (OSHA): qualified-person test wording and deenergizing rule.
• Voltage Meter Basics (Purdue University Cooperative Extension, 4-H project sheet, PDF): voltage as the difference between two points, and the hazard of live circuits.
• MM420 Instructions (Klein Tools, PDF): MM420 printed ranges, CAT III rating and meter warnings.