One of the more common types of BS 3871 circuit breaker found on installations is the Crabtree C50 which was produced in single phase and 3 phase versions. These are all Type 2 circuit breakers and their fault current rating can be determined by the infill paint in the operating handle. White paint infill indicates a 3kA rating and yellow paint indicates a 4.5kA rating.

Please also note certain Items may require additional delivery charges, such as Conduit, and Fluorescent tubes. The values of earth loop impedance shown in these tables must compensate for conductor temperature rise, if the measurement of loop impedance is taken at ambient temperature. A useful rule of thumb is to allow for a temperature rise from 20 degrees to 70 degrees by multiplying the listed value by 0.8. The measured value can then be compared to the compensated value. BS 3871 circuit breakers were also manufactured as Type 4. Generic data cannot be used for Type 4 circuit breakers and the manufacturer’s data must be used to calculate maximum values of earth loop impedance. The more common forms of Type 4 are listed in the following tables, together with their maximum values of Z s, for 0.4s and 5s disconnection times. FEDERAL Our standard deliverys are between the hours of 8am and 6pm Monday to Friday excluding national Holiday's.