IEC 61032 Access and Object Test Probes — Which Probe Verifies What.

IEC 61032, Test Probes for the Verification of Protection by Enclosures, is an unusual kind of standard: it contains no protection requirements for any product. What it standardises is hardware. Jointed test fingers, rigid pins and wires, spheres of fixed diameter — the physical probes a laboratory presses against an enclosure to find out whether fingers, tools, wires or larger objects can reach hazardous parts inside. The requirements themselves live elsewhere, chiefly in IEC 60529, which defines the IP Code, and in product safety standards for household appliances, luminaires, IT equipment and similar. Those documents state what degree of protection an enclosure must provide; IEC 61032 defines the calibrated objects used to verify it. What follows is orientation for design and quality engineers, not a test-house manual.

The division of labour with IEC 60529

The two standards are complementary and almost always used together. IEC 60529 establishes the degrees of protection, the familiar IP rating; IEC 61032 specifies the probes that turn those degrees into a physical pass/fail test. One subtlety of the IP Code is worth settling early, because it explains how the probes divide. The first characteristic numeral carries two meanings at once: protection against the ingress of solid foreign objects, and protection of persons against access to hazardous parts (back of hand at IP1X, finger at IP2X, tool at IP3X, wire at IP4X).

IEC 61032 mirrors this with two probe families. Object probes, graded from a large sphere down to a fine wire, check what can physically enter the enclosure. Access probes check what can reach a hazardous part inside; the family includes a sphere standing in for the back of a hand, a jointed finger, and rigid probes representing a tool and a wire. The same access probes also serve the additional letters IPXXA through IPXXD, which IEC 60529 provides for enclosures whose protection of persons is higher than the first numeral alone would suggest. Each probe represents a body part or an object, is applied with a defined force, and, where the test calls for it, is connected to a signal circuit that shows whether contact with the hazardous part actually occurred.

Why give probes their own standard? Reproducibility. By fixing geometry, dimensions, material and application force, IEC 61032 makes an access test in one laboratory mean the same thing as in another, and makes probes from different manufacturers interchangeable. That is the whole point of the document. Note also what it does not cover: water. The probe standard deals with access and solid objects only; the water half of the IP Code is tested by entirely different means.

Which probe verifies what

The probes group naturally by what they imitate. The notes below stay at orientation level; exact figures, tolerances and procedures belong to the standard text itself.

Probe A — the 50 mm sphere

A rigid steel sphere, 50 mm in diameter, representing the back of a hand. It is the mandatory equipment for verifying the access side of IP1X under IEC 60529, applied with a force of 50 N against every accessible opening, from every direction that can reasonably be tried. Its geometry, tolerances and application procedure are fixed in IEC 61032, and ISO 20653, the automotive IP code standard, refers to the same probe set; the sphere used on an appliance enclosure and the one used on a vehicle component are the same artefact. Laboratories working to IEC 60598, IEC 60335 or IEC 60884 use it constantly, and it is normally supplied with a calibration certificate, because a sphere that has been dropped or worn is no longer the probe the standard describes.

Probe B — the jointed test finger

The best-known probe in the set. An articulated test finger whose shape and dimensions are defined in clause 6.1.2.b, Figure 2 of IEC 61032; used with IEC 60529 it verifies IP2X access — can a finger reach in. The joints are standardised and the probe is applied at the force the standard specifies. One detail worth knowing when reading older test documentation is that the same finger appears under different figure numbers elsewhere, as Figure 2a of EN/IEC 60950-1 and Figure 8.4 of UL 1278, so three citations can mean one physical object.

Rigid pins and wires: Probes C, D, 31 and 32

Probe C is a 2.5 mm diameter pin, 100 mm long, behind a 35 mm stop sphere on a 10 mm by 100 mm handle. Probe D is dimensionally the same except for the pin itself, a 1.0 mm wire. Together they verify access at the IP3X and IP4X levels, checking whether a tool-sized pin or a fine wire can reach into the enclosure.

Here the catalogue gets confusing, because IEC 61032 also defines Probe 31 (2.5 mm, clause 6.1.1.4) and Probe 32 (1.0 mm, clause 6.1.1.3), same diameters under separate definitions, cited by different documents. Probe 31 turns up in UL 61010-1 work; Probe 32 in EN 60529 small-object ingress checks at the IP4X level. Which one a test plan needs is decided by the clause the product standard invokes, not by the diameter alone.

Tool access: Probes 12 and 13

These check whether live parts can be reached with a tool, a screwdriver being the classic case. Probe 12 is a 4 mm diameter pin, 50 mm long; Probe 13 is shorter at 15 mm, with a 3 mm tip on a 4 mm shank. Both are referenced from IEC 60065, IEC 60335-1 and IEC 60950, and both are applied at the force the standard prescribes rather than by feel.

Probe 11 — the force-adjustable finger

Probe 11 also simulates a human finger, 80 mm long and 12 mm in diameter, in stainless steel with optional chrome plating. What sets it apart is controlled force application; the pressing force is adjustable between 10 N and 75 N, with the value taken from the test specification being run. It carries twin 50 mm polyamide discs and a 4 mm connection socket for the contact-indication circuit. Its natural habitat is the appliance world (EN 60335-1 and parts such as TS EN 60335-2-36, -2-38 and -2-12), where it verifies that barriers genuinely prevent access to live parts.

Child access: Probes 18 and 19

Two probes deal specifically with children. Probe 19 represents the reach of children younger than 36 months; Probe 18 covers ages from 36 months to 14 years. They are invoked under clauses 6.2.2.f and 6.2.2.g of IEC 61032, the standard's child-protection test conditions, and appear in test plans alongside EN 60529 and IEC 60335-1.

Probes 41 and 43

The set's larger members, drawn in Figures 16 and 17 of IEC 61032 and sitting under clause 6.2, which gathers the probe types and conditions for access testing. Probe 41 is used for testing protection against access to hot parts and to components presenting a contact risk; Probe 43 serves access-risk assessment within IP classification tests. Their dimensions and tolerances are fixed in those figures, and a test plan should take them from there rather than from a catalogue summary.

One probe, several standards

Product standards rarely ask for an access test in the abstract; they call up a specific probe by clause or figure. Probe 11 recurs through EN 60335-1 and its part 2 standards. The jointed finger appears in IT-equipment-era documents such as EN/IEC 60950-1, and the tool-access pins are cited from IEC 60065 and IEC 60950, older audio-video and IT safety standards still referenced in plenty of live documentation. UL standards mirror several probes under their own figure numbers, and ISO 20653 carries the set into automotive work. In practice this means a single physical probe may serve many test plans, but the figure number, the application conditions and the acceptance criterion always come from the standard actually invoked. Read that one, not a summary.

Planning an access verification

A few points that decide whether the test goes smoothly:

• Start from the product standard, not from the probe catalogue. It identifies the probe by clause and figure. With duplicate diameters in the set (2.5 mm exists in both Probe C and Probe 31), the clause reference is the probe's real identity.
• Treat force as part of the specification. Probe A goes on at 50 N; Probe 11 is adjustable from 10 N to 75 N and the value comes from the test specification. Where your documentation quotes no force, the number is in the standard; it is not chosen at the bench.
• Budget for exhaustiveness. Access testing means every accessible opening, from every direction that can reasonably be applied. On an enclosure with many vents and seams this takes longer than the single line in the test plan suggests.
• Decide how contact will be detected. The standard provides for a signal circuit indicating whether the probe touched the hazardous part; the test plan should state how that indication is set up and what counts as contact.
• Treat the probe as a measuring artefact. Fixed geometry and tolerances are what make a result transferable between laboratories, so the probe's identity and calibration status belong in the test record alongside the result.

Where ULMEKA fits

ULMEKA designs and manufactures the access and object probes specified in IEC 61032, to the geometry and application forces the standard requires. Probes are available individually or as a complete IEC 60529 probe set (A, B, C, D, 11, 41 and 43), and requirements that go beyond the catalogue, such as custom probe variants or particular test configurations, are clarified at the quotation stage. For a product team the starting point is usually just a list of the probes its product standard invokes; once that list exists, the selection mostly makes itself.