Digital clamp meter 400V max AC amps is a marking, not a full spec

How to test the marking against the datasheet

Environment to record: the conductor size, the position of the conductor in the jaw, ambient temperature near 23 C if the accuracy table uses that point, and the source frequency. Method: compare the printed 400V and ampere figures with the table row, not with the carton photo. Data to keep: model, revision, accuracy as percent of reading plus counts, and the crest factor at which the table still applies. Steps: photograph the nameplate, attach the datasheet revision, list missing cells, and only then ask a second factory for an alternate.

Cell	Example question	Why it changes the buy
400V max	Is 400V the measurement range, the terminal rating, or marketing text?	A voltage range and a CAT working voltage are different numbers.
AC amps	What is the top range, 400 A or another figure, and the resolution?	The search phrase does not fix the ampere range.
Frequency range	Does accuracy hold from 40 Hz to 400 Hz, or only at 50 Hz and 60 Hz?	Harmonics from a drive sit outside a narrow band.
Safety category	Is the pair CAT III 600 V, CAT III 300 V, or unmarked?	IEC 61010-1 category is requested per model. This page does not certify it.
Calibration	Is the certificate dated within 12 months of shipment and tied to the serial?	An undated family claim is not traceability.

Selection trade-offs before you accept an alternate

True-RMS versus average-responding, on four columns. Bandwidth: true-RMS tables often name a wider frequency range, while average-responding tables may be valid mainly on a sine wave. Crest factor: ask whether error stays inside the stated percent at crest factor 2 and at crest factor 3. Display: both can show the same counts. Price: the average-responding unit can carry a lower unit price and still be the wrong tool on a distorted feeder. Do not subtract the prices until the RMS method matches.

New versus refurbished, same four columns. Warranty start and calibration date favor many new serials. A refurbished unit can be the available match for a legacy jaw the crew already uses, if the seller names replaced parts and the remaining interval. Connector wear on the input jacks is a mating-cycle question for both. Treat them as two offers.

Limits of the 400V phrase: it does not prove the meter may clamp a 400 V bus; it does not set measurement accuracy; it does not include the probe; and a flexible coil sold beside it can have its own scaling error. Ingress protection is a separate code if the meter leaves the bench. Power rating of the battery is irrelevant to the ampere reading but it does decide whether a 40-hour runtime claim is even on the datasheet.