Conditional verdict: The Extech 380260 makes sense when the buying question is, “Can I apply a selectable high-DC test stimulus and observe insulation resistance on a prepared, de-energized subject?” It is not a general-purpose permission slip for energized work, a compliance verdict, or a substitute for a documented test method. The strongest case is a technician, maintainer, or lab user who needs a handheld megohmmeter with 250 V, 500 V, and 1000 VDC settings, a resistance ceiling of 2000 MΩ, and a display that shows applied test voltage alongside resistance.[1][2]
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What the instrument is actually for
This is best understood as a high-DC-stimulus insulation-resistance instrument, not as an unusually large ordinary ohmmeter. Its selectable 250/500/1000 VDC megohmmeter ranges are intended to stress insulation in a controlled measurement context, while separate low-resistance, continuity, AC-voltage, and DC-voltage modes serve different diagnostic questions.[1][2]
The dual display is useful because it exposes the test voltage output and insulation-resistance reading together.[1][3]
The separate AC function is specified at 750 VAC, 40–400 Hz, and the DC function at 1000 VDC, with separately listed overload figures.[2] Those are different functions, not simultaneous independent channels or authorization for energized insulation testing. TEST and LOCK relate to the generated-stimulus test; HOLD freezes the displayed reading, not a documented saved-record or PC-export workflow.[2]
The numbers that should drive the purchase
The manual specifies 200 MΩ ranges at 250 VDC and 500 VDC with 0.1 MΩ resolution and accuracy of ±3% + 5 digits. At 1000 VDC, 0–1000 MΩ is specified at 1 MΩ resolution and ±3% + 5 digits, while 1000–2000 MΩ is ±5% + 5 digits.[2] Those are measurement conditions, not a promise that every displayed digit is meaningful in every field situation. The accuracy statement is tied to 23°C ±5°C and less than 80% relative humidity.[2]
The terminal-voltage figures are 250, 500, and 1000 V plus 20% to minus 0%.[2] Read that as the specified generated test-terminal behavior, not as an external-input rating. Likewise, the listed 1 mA entries are associated with specified loads—250 kΩ, 500 kΩ, and 1 MΩ in the range table—not a universal constant-current output claim.[2]
How to interpret a high or changing reading
The upper limit is 2000 MΩ. The manual says the display may show “1” when resistance exceeds that maximum and describes the insulation as very high and good in that context.[2] For buying decisions, treat “1” primarily as an overrange indication: it does not by itself prove universal insulation quality, safety, regulatory compliance, or suitability for a particular operating voltage. The acceptance limit must come from the equipment maker, applicable standard, or your approved test plan.
Capacitive subjects deserve special caution. The manual says the displayed resistance can increase over time and instructs the user to wait until the reading has stabilized before recording it.[2] That is guidance for interpretation, not a fixed stabilization interval or a repeatability guarantee. The 380260 is a useful observing instrument, but it does not remove the need for a consistent, documented method.
Safety boundaries are part of the buying decision
The user guide states that circuits under test must be de-energized and isolated before connections are made, except for voltage measurements, and warns not to perform insulation-resistance measurements when AC voltage is present on the device under test.[2] It also warns against touching connections during a test, calls attention to voltages above 60 VDC or 30 VACrms, and says capacitors must be discharged after insulation tests.[2] This review is limited to qualified personnel evaluating prepared, known reference components. That editorial scope is not a manufacturer ban on all industrial voltage measurement; it is not a wiring, disconnection, discharge or open-enclosure procedure.
Automatic discharge is a useful feature advertised by the maker and ordinary retail listing, but it should not be read as proof that stored energy is instantly zero or that every subject is safe to touch.[1][4] The manual’s CAT III-1000V marking sits alongside separate installation-category-II, pollution-degree-2, indoor-use, and altitude specifications, so those fields should not be casually collapsed into a blanket permission statement.[2]
Package, provenance, and version traps
The current maker page says the package includes test leads, a carrying case, and six AA batteries.[1] An older datasheet describes a different package presentation with an alligator-clip lead, hanging strap, and hard case, and separately identifies a 380260-NIST ordering variant.[3] Do not assume those older extras or traceable calibration belong to the ordinary 380260 carton. The manual says calibration and repair services are available and recommends annual calibration to verify performance; that is not evidence that this individual unit arrives calibrated to a particular certificate.[2]
The ordinary retail record reinforces the core 250/500/1000 VDC feature set and 2000 MΩ ceiling, but its product-description text also contains a Mini Hook Test Lead specification of 5 A and 300 VAC.[4] That text conflicts with the maker’s exact product presentation and should not be promoted into a 380260 lead rating, package guarantee, or permission to use the accessory in a high-DC insulation test. Confirm the exact leads, condition, and documentation supplied by the seller before relying on them.
Who should buy it—and who should skip it
Buy it conditionally if you need selectable generated high-DC stimulus for insulation-resistance checks on known, isolated, non-energized equipment or prepared reference components; you can work within the stated accuracy environment; and your organization already has a safe test method and pass/fail criterion. Its backlit dual display, resistance range, continuity and voltage modes, holster, hold, and battery operation are sensible field conveniences.[1][2]
Skip it if you need a certified compliance result from the meter alone, a data-logging or PC-export workflow, an energized-circuit insulation tester, a universal “good/bad” decision, or proof that a retail bundle contains a particular lead grade or NIST certificate. If specimen voltage tolerance, capacitive behavior or method uncertainty determines the purchase, obtain applicable documentation rather than assuming the meter supplies those answers. No physical purchase or test was performed for this review. The central fit question is not whether the display reaches 2000 MΩ; it is whether your controlled high-DC measurement task matches the instrument’s documented domain.
The buying decision
Consider the 380260 for supervised, method-driven insulation-resistance work where selectable generated DC stimulus is the reason for buying. It is not a standalone safety or compliance system. Interpret the range, overrange indication, discharge feature and category markings within the documented method, and confirm the exact supplied leads and package where they matter.[1][2][4]
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Sources
Based on the current exact maker page, its linked nine-page V2.7 June 2021 user guide, one-page May 2013 datasheet and selected ordinary offer.[1][2][3] These documents do not establish the seller’s shipped revision, accessory provenance or individual calibration.[2][4]