The Chinese standard for residual current circuit-breakers with integral overcurrent protection governs the combined devices used in Chinese consumer units, where the residual current element protects against electric shock and the overcurrent element protects the wiring, and it is applied within the compulsory certification system that covers low voltage circuit-breakers in China. The technical content follows the international document, so the classification by type of residual current, the overcurrent release characteristics and the type test programme will be familiar to a manufacturer already approved in Europe; what differs is the conformity route, which requires a Chinese certification body, a factory inspection and periodic renewal, and which means that the same product is assessed twice for two markets. The interaction of the two protective functions, particularly the behaviour when a residual current and an overcurrent occur together, is the part of the test programme that most often requires design change.