ESD Testing Equipment: What to Test and How Often
An ESD control programme is only as good as its last test. Wrist strap cords break inside the insulation, mats lose their dissipative surface to the wrong cleaner, heel grounders wear through and ionisers drift, and none of it is visible. This guide sets out what to test in an Electrostatic Protected Area, with the limits from BS EN IEC 61340-5-1, how often to do it and what to write down.
In this guide
1.Why testing matters
Every ESD control is a resistance path to ground, and every one of them degrades. A wrist strap cord flexes thousands of times a week and the conductor eventually breaks inside an unmarked sleeve. Dissipative matting is wrecked by silicone polish or household cleaner. Footwear picks up an insulating layer of dirt. Because a failed control looks exactly like a working one, the standard requires compliance verification: a documented schedule of tests, with limits, instruments and records. The limits below are from BS EN IEC 61340-5-1; your own control plan may set tighter ones.
2.Daily: wrist straps
The wrist strap system, meaning the strap, its coiled cord and the person wearing it, must measure below 3.5 × 107 Ω. A tester checks that whole path at once: the wearer plugs in the cord and presses a metal plate, and the instrument passes or fails. Most testers pass between 750 kΩ and 35 MΩ; the lower limit catches a cord whose 1 MΩ safety resistor is missing or shorted, which would be a shock hazard.
For a small team a hand-held Wrist Strap Tester on the bench is enough. For an EPA with a controlled entrance, a wall-mounted Wrist Strap Test Station at the door lets everyone test and log before they go in.
3.Daily: footwear and heel grounders
Anyone who stands or moves around relies on ESD footwear or heel and toe grounders working with dissipative flooring. The footwear and flooring system must measure below 1 × 109 Ω, with the person's body voltage kept under 100 V, or below 3.5 × 107 Ω where body voltage is not measured. Footwear alone is tested standing on a metal footwear test plate connected to the tester, one foot at a time.
A combined station does both jobs in one unit and one log entry. The Complete Wrist Strap and Footwear Test Station tests either, and the Dual Footwear and Wrist Strap Test Station tests both feet and the strap at the same time, with a 100 MΩ footwear limit for control plans that apply the 1 × 108 Ω figure. Test footwear every day it is worn, and immediately after a change of flooring cleaner.
4.Continuous monitoring at the bench
A daily test proves the strap worked at 8 am. A constant monitor proves it is working now. It sits under or on the bench, the operator's cord plugs into it, and it watches the strap-to-person path and usually the bench mat ground as well, sounding an alarm and lighting an LED the moment either is lost. It also removes the daily strap test from the routine. For seated operators handling high-value or safety-critical boards, a monitor at every position is the norm.
The Constant Monitor uses capacitive sensing, so it works with a standard single-wire wrist strap rather than needing a dual-conductor one.
5.Periodic: work surfaces and flooring
Bench mats, work surfaces, shelving and flooring are tested with a surface resistance meter and a pair of 2.3 kg electrodes. Two measurements matter:
- Resistance to groundable point (Rgp): from an electrode on the surface to the mat's earth stud or the bench's bonding point. Limit below 1 × 109 Ω for work surfaces and for flooring.
- Point-to-point (Rpp): between two electrodes on the surface, which shows whether the surface itself is still dissipative or has been sealed by polish or dirt.
Dissipative mats normally read between 106 and 109 Ω. A rising trend is the early warning; a reading over the limit after cleaning with an ESD mat cleaner means replacement. Our Surface Resistance Meter does both tests, and the Surface Resistivity Kit adds the electrodes, leads and ground cord in a case so one kit covers mats, benches, flooring and racking.
6.Periodic: garments, packaging and ionisers
Garments. Check panel-to-panel resistance, sleeve to sleeve and sleeve to body, with the surface resistance meter: below 1 × 1011 Ω for a static control garment and below 1 × 109 Ω to the groundable point for a groundable one. Test on receipt, after repair and periodically after laundering. See Why Wear an ESD Lab Coat or Jacket?.
Packaging. Shielding bags and dissipative containers are specified to IEC 61340-5-3. Verify a sample of incoming packaging with the resistance meter and keep the supplier's certificates.
Ionisers. An ioniser that has drifted out of balance charges the work instead of neutralising it. Offset voltage should stay within ±35 V and decay time within your plan's limit. This needs a charged plate monitor, which we can supply to order; call us if you run ionisers.
7.How often, and what to record
| Control | Test | Limit (IEC 61340-5-1) | How often |
|---|---|---|---|
| Wrist strap system | Tester or test station | < 3.5 × 107 Ω | Daily before use, or constant monitor |
| Footwear and flooring system | Footwear tester on test plate | < 1 × 109 Ω (with body voltage < 100 V) or < 3.5 × 107 Ω | Daily when worn |
| Work surfaces and matting | Surface resistance meter, Rgp and Rpp | < 1 × 109 Ω | Per control plan, typically every 6 to 12 months and after a change of cleaner |
| Flooring | Surface resistance meter | < 1 × 109 Ω | Per control plan, typically every 6 to 12 months |
| Garments | Panel-to-panel resistance | < 1 × 1011 Ω (groundable: < 1 × 109 Ω) | On receipt, after repair, periodically after laundering |
| Ionisers | Charged plate monitor | Offset within ±35 V; decay per plan | Per control plan, typically every 6 months |
Record the date, the item, the reading, the instrument and the operator, and what you did about any failure. The records are what an ISO 9001 or customer auditor reads first, and they are what turns a box of testers into a control programme.
