High-Voltage Test Fixture Safety

If your functional test applies supply voltages above 60V or includes a hipot (dielectric withstand) step, your electrical test fixture needs safety accessories: an interlock to lock the lid during test, a grounding kit to bond metal surfaces to earth, and an enclosed cartridge to isolate the operator from the DUT. Production bed-of-nails fixtures support all of these. Dev and Dev Pro fixtures do not.

What Triggers HV Safety Requirements#

Two scenarios move a functional test fixture from standard to high-voltage territory:

• System power supply voltages above 60V. IEC 60204-1 and IEC 61010-1 classify voltages above 30VAC or 60VDC as hazardous. Any fixture applying power above these thresholds must include interlocks and grounding.
• Hipot (dielectric withstand) testing. Hipot applies test voltages between 50V and 5kV across isolated conductors to verify insulation integrity. Even if your board's operating voltage is low, a hipot step in your test sequence triggers full HV safety requirements on the fixture.

If either applies to your test plan, you need an enclosed fixture with the safety accessories described below.

Safety Accessories for HV Fixtures#

FixturFab integrates Ingun's safety accessory portfolio into production fixtures. Three components work together to protect operators and equipment during high-voltage testing.

Interlock Devices#

The Ingun FB-SIS-ZSG-MA is a solenoid interlock that physically prevents the fixture lid from opening while the test is running. The fixture locks when the test sequence begins and stays locked until the sequence completes. If power is lost mid-test, the fixture remains locked — the system state is unknown, so the lid stays shut until power returns.

A triangular key provides manual override for maintenance access only.

Inductive Safety Switches#

The Ingun FB-ABF-V-I-MA2xxx is an inductive proximity switch that confirms the fixture lid is fully closed before the test system can energize. The test cannot start with an open fixture. This is the complementary half of the interlock — one prevents opening during test, the other prevents testing while open.

Grounding Kits#

The Ingun FB-SLV-MAxx11 grounding kit bonds all operator-accessible metal surfaces on the fixture to earth ground. If insulation fails during a test, fault current flows to earth instead of through the operator.

Grounding kits also improve measurement quality. Proper grounding reduces electrical noise that can interfere with test accuracy — particularly relevant for hipot testing, where noise can cause false pass/fail results. For ESD-sensitive DUTs, grounding stabilizes the test environment and prevents floating potentials from corrupting readings.

These three accessories are standard options on all production fixtures. FixturFab's team helps you determine which combination your application requires based on your test voltages, DUT characteristics, and facility compliance requirements.

Why Production Fixtures Are Required for HV Testing#

This is straightforward: Dev and Dev Pro fixtures have open cartridges — exposed on three sides. There is no way to enclose the DUT or prevent operator contact with energized test points.

Production fixtures use an enclosed cartridge design that fully isolates the test area. The closed cartridge provides the mechanical structure needed to mount interlock solenoids, inductive switches, and grounding connections. It also creates a physical barrier between the operator and the DUT during test execution.

Compliance Standards: IEC 60204-1 and IEC 61010-1#

Two international standards govern electrical safety requirements for test fixtures:

IEC 60204-1 (Safety of Machinery — Electrical Equipment) defines requirements for electrical equipment in machines, including test systems. It mandates interlocking and grounding for equipment operating above hazardous voltage thresholds.

IEC 61010-1 (Safety Requirements for Electrical Equipment for Measurement, Control, and Laboratory Use) applies specifically to test and measurement equipment. It requires that operators cannot contact hazardous voltages during normal operation, and that single faults do not create hazardous conditions.

For test fixture specifications, the practical takeaways are:

• Voltages above 60VDC (or 30VAC) require physical interlocking
• All operator-accessible metal surfaces must be grounded
• The fixture must prevent test initiation with the lid open
• Power loss must leave the fixture in a safe state (lid locked)

When specifying a fixture, communicate your test voltages, hipot requirements, and any facility-specific compliance needs to your fixture vendor. These standards are what your CM's safety team will audit against.

A Note on Hipot Testing#

Hipot testing — also called hi-pot, high potential, or dielectric strength testing — verifies that insulation between isolated conductors on your PCBA can withstand voltage stress well above operating levels. Per IPC-TM-650, standard DC hipot conditions for common PCB insulation tests are 500V (Condition A) or 1000V (Condition B) with a 5-second ramp and 30-second dwell. A common industry guideline for other applications is 2x working voltage + 1000V, though the specific test level depends on the applicable product standard and purpose of the test.

Hipot can reveal defects that standard continuity and isolation tests miss, such as resin voids, incomplete etching, ionic contamination from flux residue, and insufficient trace-to-trace clearance.

There are two distinct dielectric test fixture types:

• Dedicated hipot enclosures — purpose-built for dielectric testing, with the board de-energized during test. FixturFab designs these as standalone high-voltage test enclosures linked to your hipot tester.
• Functional test fixtures with HV safety accessories — your board runs powered at operating voltage, and hipot is one step in the test sequence. Same safety infrastructure (interlocks, grounding, enclosed cartridge), different test context.

Both require enclosed fixtures with the accessories described above. If you're unsure which applies to your test plan, talk to us.

Frequently Asked Questions#

Do I need an interlock for hipot testing?#

Yes. Hipot testers require an interlock interface — the tester will not apply high voltage unless it detects a closed, locked fixture. This is a safety requirement of both the tester hardware and IEC 61010-1.

What voltage triggers a safety interlock on a test fixture?#

IEC 60204-1 and IEC 61010-1 classify voltages above 60VDC (or 30VAC) as hazardous. Any test fixture operating above these thresholds needs interlocks, grounding, and an enclosed design.

Can I use a Dev or Dev Pro fixture for high-voltage testing?#

No. Dev and Dev Pro fixtures are open on three sides. They cannot accept interlocks or grounding kits, and they do not enclose the DUT. If your test applies voltages above 60V or includes hipot, you need a production fixture.

What happens if power is lost during a high-voltage test?#

The interlock solenoid keeps the fixture lid locked. The system state is unknown during power loss, so the fixture remains in its safe (locked) state until power and system functionality are restored to a known state. A triangular key provides manual override for maintenance access only.

Next Steps#

• Need help with HV requirements? Contact us to discuss your specific test voltages, hipot specs, and compliance needs.
• Exploring testing methods? See our testing methods overview for a comparison of ICT, functional testing, boundary scan, and flying probe.
• Already know you need production fixtures? Learn more about production fixture capabilities.