IEEE 402-1974

402-1974 is a technical standard focused on insulation materials at high direct voltages, providing guidance for evaluating how insulating systems behave under DC stress. It is relevant to power, energy, and industrial applications where dielectric performance can affect reliability, safety, and equipment life. By addressing insulation materials in this electrical context, 402-1974 helps support consistent selection, testing, and engineering decisions for components and systems exposed to sustained high-voltage conditions.

Overview of 402-1974

This standard addresses the performance expectations for insulation materials used at high direct voltages, a context where electrical stress can differ from alternating-voltage service. 402-1974 is useful for engineers and technical buyers who need a clearer basis for comparing materials, designing insulation structures, or reviewing acceptance requirements. In applications involving devices, circuits, and engineered dielectric materials, the document helps define a more controlled approach to material behavior, loss, and breakdown resistance under DC conditions.

Typical use cases

402-1974 is commonly relevant when specifying insulation for high-voltage DC equipment, test assemblies, and power-related components. It may be used in the development or review of bushings, cable insulation, machine windings, and other dielectric structures where long-term voltage endurance matters. The standard can also support laboratory testing, supplier qualification, and engineering documentation for materials used in energy systems, electrical apparatus, and industrial installations that depend on stable insulation performance.

Why it matters

For organizations working with high direct voltages, 402-1974 can help reduce uncertainty in material selection and performance verification. Clear expectations for insulation behavior support safer design choices, more consistent procurement, and better alignment between engineering requirements and testing practice. Using a defined standard also helps limit the risk of premature dielectric failure, unexpected leakage, or degraded performance in service. In this way, 402-1974 supports both technical confidence and practical risk management.

• High-voltage DC insulation performance
• Dielectric material evaluation
• Component and system specification
• Testing and acceptance criteria
• Engineering and procurement reference