The IEC develops international standards for switchgear. South Africa though has developed its own standard for circuit breakers which is 95% similar to IEC standards but with an important difference. IEC mandates that circuit breakers should be able to operate at 230 volts +/-5% but the South African requirement is 230 volts +/- 10%. Most circuit breakers on the world market cannot meet the South African standard, and are more expensive for those countries that do make them (e.g. Siemens). This affords some protection to the South African industry.