Wiring 133/230Y System

broadgage:

That is very rare in the UK, is this overseas ?

You may need larger conductor sizes to keep voltage drop down.

For a two wire 230 volt circuit, voltage drop will be same as a UK standard circuit. Earth loop impedance may require larger conductors, since only 133 volts is available to earth rather than 230 volts.

However during an earth fault, the potential touch voltage is reduced to about 65 volts, less dangerous than the 115 volts on a standard UK system.


Standard MCBs and fuses can be used, the voltages marked on these are MAXIMUM voltages, NOT the required voltage. MCBs must be true double pole devices, not single pole and neutral.


RCDs for 2 wire circuits can be standard types, as the voltage between live conductors is the same as a standard UK supply. RCDs must be true two pole and not single pole and neutral.


Switches for lamps and appliances should be double pole, to open both live conductors.


If UK type 13 amp plugs/sockets are to be used, then these should be on circuits of 16 amps or less. 

Thanks


Do I use 0.8 seconds instead of 0.4 for my disconnection time?


Regarding switches for lamps I can't see the need for switching both poles as you are only controling the light instead of using the switch as safety isolation.

broadgage:

That is very rare in the UK, is this overseas ?

You may need larger conductor sizes to keep voltage drop down.

For a two wire 230 volt circuit, voltage drop will be same as a UK standard circuit. Earth loop impedance may require larger conductors, since only 133 volts is available to earth rather than 230 volts.

However during an earth fault, the potential touch voltage is reduced to about 65 volts, less dangerous than the 115 volts on a standard UK system.


Standard MCBs and fuses can be used, the voltages marked on these are MAXIMUM voltages, NOT the required voltage. MCBs must be true double pole devices, not single pole and neutral.


RCDs for 2 wire circuits can be standard types, as the voltage between live conductors is the same as a standard UK supply. RCDs must be true two pole and not single pole and neutral.


Switches for lamps and appliances should be double pole, to open both live conductors.


If UK type 13 amp plugs/sockets are to be used, then these should be on circuits of 16 amps or less. 

Thanks


Do I use 0.8 seconds instead of 0.4 for my disconnection time?


Regarding switches for lamps I can't see the need for switching both poles as you are only controling the light instead of using the switch as safety isolation.