IEC TS 60815-4:20 16（E）是一项技术规范，适用于作为确定所需d.c.的第一种方法。绝缘子关于污染的统一比爬电距离。为了避免设计过度或设计不足，应比较现有的操作经验，并最终通过供应商和客户之间的协议进行额外的适当测试。它适用于: -玻璃和瓷绝缘体； -具有HTM或非HTM外壳的复合绝缘子和混合绝缘子。IEC 60815的这一部分给出了具体的指南和原则，以对给定绝缘子在某些污染环境中的可能行为做出明智的判断。

IEC TS 60815-4:2016(E) which is a Technical Specification, is applicable as first approach for the determination of the required d.c. Unified Specific Creepage Distance for insulators with respect to pollution. To avoid excessive over or under design, existing operation experience should be compared and eventually additional appropriate tests may be performed by agreement between supplier and customer. It is applicable to:
- Glass and porcelain insulators;
- Composite and hybrid insulators with an HTM or non-HTM housing. This part of IEC 60815 gives specific guidelines and principles to arrive at an informed judgement on the probable behaviour of a given insulator in certain pollution environments.