Hello all,
I have a 2 way CU in my shed with a 16A MCB for the radial (3 double sockets) and 6A MCB for the lights (four of them, max usage 330w). I have 20 metres of SWA 4mm[SUP]2 [/SUP]which I will take to the house from the shed and then use 4mm[SUP]2 [/SUP]in trunking to the CU.
I then presumed I would have to use a 32A MCB (in the house CU) as it would have to be greater or equal to the total of the 2 way CU in the shed, but...
The OSG states that 4mm[SUP]2[/SUP] (in trunking) can take up to 30A which is absolutely fine for my shed but the MCB obviously has to trip at less than the current carrying capacity of the cable so it should be between 22A (max of the 2 way consumer unit in shed) and 30A.
It seems crazy to use 6mm[SUP]2[/SUP] when I dont need that many amps and already have 20metres of 4mm[SUP]2[/SUP] SWA.
Am I missing something very simple? What MCB should I use in main CU?
Thanks..
I have a 2 way CU in my shed with a 16A MCB for the radial (3 double sockets) and 6A MCB for the lights (four of them, max usage 330w). I have 20 metres of SWA 4mm[SUP]2 [/SUP]which I will take to the house from the shed and then use 4mm[SUP]2 [/SUP]in trunking to the CU.
I then presumed I would have to use a 32A MCB (in the house CU) as it would have to be greater or equal to the total of the 2 way CU in the shed, but...
The OSG states that 4mm[SUP]2[/SUP] (in trunking) can take up to 30A which is absolutely fine for my shed but the MCB obviously has to trip at less than the current carrying capacity of the cable so it should be between 22A (max of the 2 way consumer unit in shed) and 30A.
It seems crazy to use 6mm[SUP]2[/SUP] when I dont need that many amps and already have 20metres of 4mm[SUP]2[/SUP] SWA.
Am I missing something very simple? What MCB should I use in main CU?
Thanks..
