Multimeter
Klein Tools MM400
Auto-ranging digital multimeter covering AC/DC voltage, current, resistance, continuity, capacitance and temperature.
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Best for
A first multimeter that will not be outgrown for home work
Specifications
| Voltage | Up to 600 V AC/DC |
|---|---|
| Measures | Voltage, current, resistance, continuity, capacitance, duty cycle, temperature |
| Safety rating | CAT III 600 V |
Specifications as published by Klein Tools. Confirm against the current spec sheet before buying — manufacturers revise models without renaming them.
What's good
- Auto-ranging removes the main way beginners get a wrong reading
- Capacitance and temperature cover most appliance-repair questions
- Includes leads and a thermocouple in the box
What's not
- Not true-RMS — readings on variable-speed and inverter-driven loads will be off
- CAT III 600 V is fine at a panel but not for service-entrance work
Our verdict
The right first multimeter for a homeowner: enough capability to diagnose an appliance, priced so it is not a painful purchase. If your work involves mini splits, inverter generators or variable-speed motors, skip straight to a true-RMS meter — averaging meters read those loads wrong, and being confidently wrong is worse than having no meter.
Compare with the alternatives
- Klein Tools NCVT-3P — confirming a circuit is dead before you open a device or box
- Fluke 1AC-A1-II VoltAlert — a simple, rugged live/dead check on 120 v and 240 v branch circuits
- Sperry Instruments GFI6302 — checking every outlet in a house quickly for miswiring
- Klein Tools RT250 — diagnosing voltage drop or a flaky circuit, not just wiring order
- Klein Tools ET310 — labeling a panel without two people and a lot of shouting
- Fluke 117 — anyone who will do this more than once a year
- Klein Tools CL800 — finding out what a circuit or appliance is actually drawing
- Fluke 323 — measuring current in a tight, densely packed load center