Got a job to do when the lock down ends.
Customer is having a EV Charging point installed by a 3rd party into his garage, and the consumer unit in the garage needs upgrading (extra way) with a Type A RCD (EVCE has DC monitoring internally) . Existing supply to garage is 16A and due to the house being rented customer doesn't want to replace the buried cable, so EV Charging Installer is going to de-rate the charger to 3kW.
Existing installation is TT, supplied by overheads and CRL would recommend SPDs are fitted. Garage is fed from a dual RCD board with Type AC RCDs.
So 1st of all I have to take the garge supply out of the existing consumer unit and protected it was a Type A 100mA time delayed RCD with a relevant MCB (20A).
Now because the supply is overhead I'm led to believe that a Type 1 SPD is required to be fitted at the origin. One supplier of a Type 1 SPD, recommends that it is protected by a 63A MCB, and also says an RCD should not be installed upstream of this type of SPD as there is potential leakage. 534.4.7 also confirms this.
So I now have to put the following components in a new enclosure (or enclosures), 63A MCB, SPD, RCD and 20A MCB, in that order. Because its a domestic then these should all be enclosed in a metal enclosure, I assume these come under the 'Switchgear assemblies' definition. But I am nervous that I would have incoming tails to a metal enclosure that connect to a MCB which then connects to the SPD before we get to RCD protection!
How do I overcome this and keep to the regs?
