IEC 60068-2-78:2025

Overview

IEC 60068-2-78:2025 - "Environmental testing - Part 2-78: Tests - Test Cab: Damp heat, steady state" defines a laboratory test method to assess the ability of components and equipment to withstand high humidity at constant temperature without condensation. Applicable to both small and large items, and to heat‑dissipating and non‑heat‑dissipating specimens, this third edition (2025) replaces the 2012 edition and introduces significant technical updates to chamber requirements, severities (including dew point specification), tolerances, preconditioning, and test reporting.

Key topics and technical requirements

• Test objective: Evaluate effects of moisture absorption and vapor diffusion during exposure to sustained high humidity at constant temperature (no condensation).
• Test severities: Preferred temperature/RH combinations (examples):
  • 30 °C ± 2 K / 93 % RH ± 3 %
  • 30 °C ± 2 K / 85 % RH ± 3 %
  • 40 °C ± 2 K / 93 % RH ± 3 %
  • 40 °C ± 2 K / 85 % RH ± 3 %
• Methods I–IV: Defined ranges with corresponding dew point temperatures (provided in the standard) to better characterise humidity severity.
• Test durations: Preferred durations include 12 h, 16 h, 24 h, 2 days, 4 days, 10 days, 21 days, 56 days.
• Test chamber requirements: Updated to align with IEC 60068-3-6 - chamber volume, sensor placement, draining/purification of condensate, non‑radiant specimen exposure, injection of moisture remote from specimen, and water conductivity limits.
• Preconditioning: A specified preconditioning procedure is now included to standardize specimen state before conditioning periods.
• Measurement and reporting: Revised standardized requirements for the test report and clearer measurement definitions (initial, intermediate, final).
• Temperature tolerance: The document changes temperature tolerances to defined limits (e.g., total temperature tolerance ±2 K), reflecting tighter control expectations.

Applications and users

IEC 60068-2-78:2025 is used for:

• Environmental testing laboratories and climatic test chambers
• Manufacturers of electronics, electrical equipment, automotive, aerospace, and industrial products
• Design, reliability and qualification engineers assessing humidity resistance, corrosion risk, insulation degradation, and component lifetime
• Quality, compliance and regulatory teams preparing test evidence for product approval and reliability claims

Practical benefits include consistent humidity test setups, repeatable severity definitions (including dew point), and standardized reporting for procurement and certification.

Related standards

• IEC 60068-1:2013 - General and guidance
• IEC 60068-2-67 - Damp heat, steady state (accelerated/component test)
• IEC 60068-3-6 / 3-7 - Chamber performance and operation guidance
• IEC Guide 104 - Safety publications guidance

Keywords: IEC 60068-2-78:2025, damp heat steady state, environmental testing, high humidity test, test chamber, dew point, preconditioning, reliability testing.