The Hioki Phase and Voltage Detector Series is a family of handheld instruments for verifying the live state of AC lines and checking three-phase phase sequence. The series includes non-contact voltage detectors that confirm a hot line through the wire or cable covering, phase detectors that indicate positive and negative phase rotation, and a digital phase detector that measures three-phase voltage and frequency directly. Each instrument signals its result with LED indicators and an audible buzzer.

Across the series the detectors perform live-line checking, positive and negative phase-sequence detection, open-phase (missing-phase) prediction, ground-phase prediction on three-phase lines, three-phase line voltage measurement, and frequency measurement. Together these functions support inspection of three-phase power lines, where confirming phase rotation and a live or de-energized state is part of the routine check.

ValueTronics stocks and holds its own inventory in a 20,000-square-foot secure warehouse at 1675 Cambridge Drive in Elgin, Illinois. Holding our inventory directly lets our Test Architects confirm availability and condition before you order.

Compare Other Models in This Series

The Hioki Phase and Voltage Detector Series brings together two related instrument types in one line: non-contact AC voltage detectors that confirm whether a wire is live through its covering, and phase detectors that determine three-phase rotation and related conditions. The 3481-20 is a compact, pocket-sized voltage detector; the PD3129 and PD3129-10 are no-metal-contact phase detectors; and the PD3259-50 is a digital phase detector with a numeric display.

Each model targets a different conductor size and voltage envelope, so the right choice depends on the line being inspected. The comparison table below lays out the operating voltage, frequency, conductor compatibility, safety category, and detection functions for each model side by side.

Each new model listed below is its own dedicated product page with condition-matched pricing. Select the specific model that matches the conductor size, voltage range, and detection functions your work requires, then choose the listing for the condition you need.

The PD3259-50 digital phase detector is the data-capable model in the series. Beyond phase-sequence and open-phase detection, it measures three-phase line-to-line and line-to-ground voltage from 90.0 to 520.0 V AC and frequency from 45 to 66 Hz, displays an unbalance rate and vector diagram, and predicts a grounded phase on a three-phase line. It carries an IP54 rating for the device body.

The clearest differences are voltage and conductor range. The 3481-20 voltage detector works from 40 to 600 V AC on conductors handled by its non-contact tip; the PD3129 phase detector covers 70 to 600 V AC on insulated wiring from φ2.4 to φ17 mm; and the PD3129-10 extends to 70 to 1000 V AC on thicker conductors from φ7 to φ40 mm. The PD3259-50 measures three-phase voltage from 90.0 to 520.0 V AC on finished outer diameters of 6 to 30 mm (shielded cables not supported).

Safety category and feature set differ as well: all models are rated CAT IV 600 V, while the PD3129-10 adds CAT III 1000 V for its higher voltage range. The phase detectors signal rotation with LEDs, a buzzer, and a green arrow, whereas the PD3259-50 adds a digital display with optional Z3210 Bluetooth connectivity. Refer to the comparison table for the per-model specifications.

Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.

Accessories Supplied

• Carrying case
• Strap
• R6P manganese battery ×2
• Spiral tube
• Instruction manual

Product Core & Specifications

Important: Soil, residue, or moisture on the insulated wires may result in lower voltage and power values than their true values; use a dry cloth to remove before measuring.

Important: Never measure a measurement point with a higher category number than the category indicated on the measuring instrument. Doing so could lead to a serious accident such as electric shock.

Important: PD3259-50: Shielded cables are not supported as measurement targets.

Important: PD3259-50: Continuous operating time of 5 hours is specified for operation without the Z3210 wireless adapter.

Usage tip: add the optional Z3210 Wireless Adapter to the PD3259-50 to enable Bluetooth transfer of measurement data into the GENNECT Cross app for reports and data management.

ValueTronics supplies both new and used test and measurement equipment. New units ship factory-sealed, exactly as received from the manufacturer; every used unit is inspected and functionally verified in-house at our 20,000 sq ft secure facility in Elgin, Illinois before it ships. Our Test Architects can help you select the condition, calibration, and configuration that fit your application.

Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.