... test, according to GB12666.6Class A, burn in fire with flame temperature 950°C, apply voltage of 750V between phase and phase and ... for 90min without breakdown.Class B, bun in fire with flame temperature 750-800°C, apply voltage of 750V between phase and phase ... the following requirements:Class A 650°C 3hClass B 750°C 3hClass C 950°C 3hClass S 950°C 20minElectrical characteristics(1) Rated voltage: 0 ...