Quick Response Comparator Offering Reading Stability in High-speed Digital Format


The IR4059 is a Bluetooth® compatible insulation tester. It has a 5-range, 50 V to 1000 V digital insulation resistance tester with bargraph and delivers efficient functions and features to help shorten the work time associated with field insulation testing.


Best for measuring the insulation resistance of electric vehicles.

The IR4059 is the ideal insulation tester for a technician to use when checking the insulation resistance of an electric car, thanks to its safety features, reliable performance, and user-friendly design.

Key Features

  • 5-range testing voltage of 50 V/100 MΩ to 1000 V/4000 MΩ
  • Digital bar graph
  • Multi-functional test lead with remote switch improves work efficiency: flashlight, remote test start, LED light for PASS/FAIL notification.
  • Stable and high-speed digital readings; 0.3 second response time for PASS/ FAIL judgment.
  • Bright LED, luminous LCD, test lead (included accessory: L9788-10) with bright LED lamp to illuminate near hand.
  • Continuity check via 200 mA testing
  • Built in AC/DC voltage meter, useful for testing solar power generation systems and electric vehicles
  • Easily transfer measurement data to your smartphone or tablet by using our free app GENNECT Cross or to an Excel® file. (Wireless Adapter Z3210 is necessary)
  • Drop proof onto concrete from 1m (3.28 feet)

Model No. (Order Code)


Data can be downloaded to tablets and smartphones using Hioki’s dedicated free app "GENNECT Cross," available from the Google Play or App Store.

Correct voltage selection for equipment safety needs

The IR4059's high-voltage range (500V or 1000V) integrates an ingenious safety feature. Technicians are prompted to unlock when selecting the voltage—a pivotal step to prevent accidental high-voltage application to low-voltage equipment.

With our innovative solution, precision and safety converge seamlessly, guaranteeing error-free operations every time.

Comparator function provides PASS/ FAIL decisions at a glance

Compare measured values to pre-set reference values to generate a pass or fail judgment with the Comparator function.
(also pair with insulation resistance measurement and low-resistance measurement)

The insulation testers give you pass/ fail results using a beeping sound, LCD light, and indication right on the test lead with remote control switch (included accessory), letting you check for insulation integrity without needing to look at the instrument.

Significantly improve testing speed using test lead with remote switch

With these four capabilities, the test lead with remote switch L9788-10 (included accessory) will speed up the measuring procedure.
1. LED light shines a spotlight on the target
2. Red light warns of live voltage detection
3. Measurement start switch
4. Identify pass/fail decisions with red or green light

Hands-free insulation testing: Effortless readings where you need them

Revolutionize Your Testing Experience:Secure the insulation tester to switchboard doors or the vehicle using the magnetic strap Z5020.
This novel feature allows you to perform insulation tests while checking readings at eye level.

Instantly create reports by a free app (GENNECT Cross)

GENNECT Cross, a free app designed specifically for use with Hioki measuring instruments, lets you check and manage measurement results and create reports.
The software provides a range of functionality that helps manage data in the field, including photographing measurement sites, placing measurement results on photographs, and saving hand written memos.

Optional Wireless Adapter Z3210 is necessary.

Click here for details about GENNECT Cross

Wireless support: Wireless communication capability for even greater convenience than legacy model

Compatible with Wireless Adapter Z3210 (optional). It transfers measurements to your smartphone or tablet and allows you to quickly create reports with field photos and drawings.

See details about Wireless Adapter Z3210

Easily transfer measurement data to an Excel® file

Excel® Direct Input function allows you to input measurement values directly and automatically into an Excel® file once the instrument's auto-hold function is activated. (Wireless Adapter Z3210 is necessary)

White LED lighting that’s easy to read in dim locations in the field

The scale is lit by a white LED, ensuring that insulation resistance values are easy to read, even when using the instrument in a dim location.

How to Use Digital Insulation Resistance Meters - Basic Course

This video explains how to use a digital insulation resistance tester to measure a distribution panel.
※ Shooting was done with Japanese model IR 4052-50. The global model name is IR4059.

Robust, damage-resistant design

These instruments feature a robust design that can withstand being dropped onto concrete from a height of 1 m.
Difficult to damage, this insulation tester is ideal for use in the field.

Measurement switch designed for outstanding ease of use

The instrument’s measurement switch can be operated with just the thumb.
Press for a single measurement or lift up for continuous measurement of insulation resistance.

200 mA grounding line continuity check function

The Insulation testers can perform EV and HEV continuity checks as well as resistance measurement of safety conductors in building electrical equipment as defined by IEC 60364.

Basic specifications

Accuracy guaranteed: 1 year
Rated output voltage 50 V DC 125 V DC 250 V DC 500 V DC 1000 V DC
Effective maximum indicated value 100 MΩ 250 MΩ 500 MΩ 2000 MΩ 4000 MΩ
1st effective measuring range MΩ
±2 % rdg. ±2 dgt.
0.200 - 10.00
±2 % rdg. ±2 dgt.
0.200 - 25.0
±2 % rdg. ±2 dgt.
0.200 - 50.0
±2 % rdg. ±2 dgt.
0.200 - 500
±2 % rdg. ±2 dgt.
0.200 - 1000
Lower limit resistance 0.05 MΩ 0.125 MΩ 0.25 MΩ 0.5 MΩ 1 MΩ
Overload protection 600 V AC (10s) 660 V AC (10s)
DC voltage range 4.2 V (0.001 V resolution) to 600 V (1 V resolution), 4 ranges,
Accuracy: ±1.3% rdg. ±4 dgt., Input resistance: 100 kΩ or higher
AC voltage range 420 V (0.1 V resolution) / 600 V (1 V resolution), 2 ranges, 50/60 Hz,
Accuracy: ±2.3% rdg. ±8 dgt., Input resistance: 100 kΩ or higher, Average rectifier
Low resistance range For checking the continuity of ground wiring, 10 Ω (0.01 Ω resolution) to 1000 Ω (1 Ω resolution), 3 ranges, Basic accuracy: ±3 % rdg. ±2 dgt., testing current 200 mA or more (at 6 Ω or less)
Display Semi-transmissive FSTN LCD with back lighting, bar-graph indicator
Response time Approx. 0.3 second for PASS/FAIL decision (based on in-house testing)
Other functions Indicate MΩ measurement value after a lapse of one minute, Live circuit indicator, Automatic electric discharge, Automatic DC/AC detection, Comparator, Drop proof, Auto power save
Power supply LR6 (AA) alkaline batteries × 4, Continuous use: 20 hours (based on in-house testing)
Number of measurements: 1000 times (at 5 s ON, 25 s OFF cycle, insulation measurement of lower limit resistance value to maintain nominal output voltage)
Dimensions and mass 160 mm (6.30 in) W × 98 mm (3.86 in) H× 46 mm (1.81 in) D, 536 g (18.9 oz) (including batteries, excluding test leads)
Included accessories Connection cable L4930 ×1, Alligator clip set L4935 ×1, Test pin set L4938 ×1, Neck strap ×1, Test lead set with remote switch
(Red) LR9788-10×1, Protector Z5042×1, Instruction manual ×1, LR6 (AA) alkaline batteries ×4

Test lead/Connection cable (4)

*The L4930, L9788-10 are bundled

L9788-10 options (2)

Exclusively for the L9788-10

L4930 options (6)

Exclusively for the L4930
*The L4935, L4938 is bundled

Carrying case (1)

*EV maintenance manual is included

Others (2)

Z5042 is bundled