I have been asked to supply a garage/stables with some sockets, they are reluctant to have a CU due to cost and will be converting the whole space completely in the next 5 years or so and will do it ‘properly’ then and they just want some power out there for now.
There is a 32a MCB on the main CU in the house which feeds a junction box in what I believe to be 4mm T+E at the other end of the house which is around 10m from the CU. This junction box is just inside the wall of the house, where I would connect the T+E to some 4mm swa and then run the swa under the car park to the garage ( ducting is in place ). Around 15m to the first socket from the junction box then into another 2 stables ( there is 3 side by side ). I imagine I’ll use 40m of SWA from the junction box inside the house to last socket in the last stable, so 10m T+E and 40m swa, 50m in total. All 4mm.
The load used at one time should never exceed 4000w so 18 ish amps. A granny charger at night for their car and in the day a heater, speaker and a light for the home gym.
Voltage drop should be okay per my calculations. 50m, 4mm T+E, clipped in ceiling board.
Current carrying capacity of 4mm T+E can vary, I’m confused on the reference method. It is clipped but direct, in an open ish space in a wall, less then 100mm.
The swa is xlpe and rated to 42amps so no worries.
So my question is should I replace the 32A MCB for a 20A MCB?
Or should I upgrade the 4mm T+E to 6mm or would be 4mm okay and I’ll let the client know that in the future that would need upgrading.
I know this may appear basic to some, I’ve just entered into more domestic electrics and was doing a lot of fault finding and testing before. I’ll be thankful of any help and tips.
There is a 32a MCB on the main CU in the house which feeds a junction box in what I believe to be 4mm T+E at the other end of the house which is around 10m from the CU. This junction box is just inside the wall of the house, where I would connect the T+E to some 4mm swa and then run the swa under the car park to the garage ( ducting is in place ). Around 15m to the first socket from the junction box then into another 2 stables ( there is 3 side by side ). I imagine I’ll use 40m of SWA from the junction box inside the house to last socket in the last stable, so 10m T+E and 40m swa, 50m in total. All 4mm.
The load used at one time should never exceed 4000w so 18 ish amps. A granny charger at night for their car and in the day a heater, speaker and a light for the home gym.
Voltage drop should be okay per my calculations. 50m, 4mm T+E, clipped in ceiling board.
Current carrying capacity of 4mm T+E can vary, I’m confused on the reference method. It is clipped but direct, in an open ish space in a wall, less then 100mm.
The swa is xlpe and rated to 42amps so no worries.
So my question is should I replace the 32A MCB for a 20A MCB?
Or should I upgrade the 4mm T+E to 6mm or would be 4mm okay and I’ll let the client know that in the future that would need upgrading.
I know this may appear basic to some, I’ve just entered into more domestic electrics and was doing a lot of fault finding and testing before. I’ll be thankful of any help and tips.
