1.5mm² T&E, 16A MCB, 2 Double Sockets

[stuz]

Hi,

I have installed a mini CU in my shed which is currently unconnected to the main supply in the house. Once I have finished wiring the shed I will get a professional in to certify the job and connect up the shed to the house. The two double sockets radial circuit hangs off a 32A MCB, the lighting circuit hangs off a 6A MCB. I have erroneously cabled up the sockets with 1.5 mm² twin and earth which is bare mounted to the wooden structure and secured with plastic cable clips, no pinches or tight bends. My understanding is that this cable would be rated at 20A in this configuration.

The intended use for the sockets is charging bike lights, battery packs for power tools, a radio etc, nothing heavy. Would it be acceptable/safe to switch out the 32A MCB in the CU for a 16A one, or should I re-cable with 2.5mm² ? Obviously I would prefer to avoid the latter if possible.

Thanks

Stuz

 

[EFLImpudence]

I have installed a mini CU in my shed which is currently unconnected to the main supply in the house. Once I have finished wiring the shed I will get a professional in to certify the job and connect up the shed to the house.

Ok. It doesn't really work like that.

The two double sockets radial circuit hangs off a 32A MCB, the lighting circuit hangs off a 6A MCB.

The circuits should be connected properly; not hanging off.

I have erroneously cabled up the sockets with 1.5 mm² twin and earth which is bare mounted to the wooden structure and secured with plastic cable clips, no pinches or tight bends. My understanding is that this cable would be rated at 20A in this configuration.

It would be but you have it protected by a 32A MCB.

The intended use for the sockets is charging bike lights, battery packs for power tools, a radio etc, nothing heavy. Would it be acceptable/safe to switch out the 32A MCB in the CU for a 16A one,

Yes.

or should I re-cable with 2.5mm² ? Obviously I would prefer to avoid the latter if possible.

It is not clear whether you have installed a ring circuit or a radial. There is not much point having a ring circuit in a shed.

A 32A radial would require 4mm² cable.

 

[stuz]

Hi,

Thanks for the quick reply.

Ok. It doesn't really work like that.

So the process wouldn't be for me to wire up my shed and then contact an electrician to certify the work and cable/connect up to the mains?

The circuits should be connected properly; not hanging off.

Yes, connected properly, hanging off was perhaps the wrong choice of expression!

It would be but you have it protected by a 32A MCB.

The question is can I simply replace the 32A MCB in the CU with a 16A one and not have to re-wire the socket radial?

Yes.


It is not clear whether you have installed a ring circuit or a radial. There is not much point having a ring circuit in a shed.

A 32A radial would require 4mm² cable.

It's Radial. So if I were to keep the 32A MCB I should re-wire with 4mm not 2.5mm for the sockets, got it. But keeping the 1.5mm and replacing the 32A MCB with a 16A MCB would be OK?

Thanks again

Stuz

 

[EFLImpudence]

So the process wouldn't be for me to wire up my shed and then contact an electrician to certify the work and cable/connect up to the mains?

Anyone can "certify" electrical work so the person doing it should certify it - or someone else should be employed before the work commences and supervise throughout.

Here "certify" does not mean "notify" the Local Authority which a new circuit requires. This should also be done before the work starts and then you will have to do what the LA say - or employ a registered electrician.

The question is can I simply replace the 32A MCB in the CU with a 16A one and not have to re-wire the socket radial?

Yes.

It's Radial. So if I were to keep the 32A MCB I should re-wire with 4mm not 2.5mm for the sockets, got it. But keeping the 1.5mm and replacing the 32A MCB with a 16A MCB would be OK?

Correct.

 

[stuz]

Thank you @EFLImpudence