TODAY I am replacing an old consumer unit with faulty MCB’s and a broken cover. Here is how it is done step-by-step in a Spanish installation. I am using Chint switchgear.

Step 1: Make a note of what you started with, i.e. label and identify the sub-circuits, where do the cables enter the box, etc.

Step 2: Mark and cut the hole for the new back box covering the existing hole. New consumer units usually come with a template. Note: you may need to keep the power switched on if using a power tool, if so, proceed with caution.

Step 3: Isolate the electricity supply by remove the main fuse in the meter cupboard. Then disconnect the old switches and remove the back box.

Step 4: Cut out the cable conduit entry holes, then fit the new back box into the wall using cement.

Step 5: Clip the new RCD’s and MCB’s to the DIN rails. Here we are rewiring the consumer unit for a split load using two RCD’s. Note: All the MCB’s are 2-pole (1P+N).

Step 6: Wire in the tails according to the electric load for the installation. Here I am using a 10 mm 2-pole busbar and cable tails. I had to extend the mains supply cables.

Step 7: Re-connect the sub circuits, then finally the earth conductors.

Step 8: All the wiring is connected, fit covers.

Step 9: Job done. This is a typical split load consumer unit found in Spanish domestic dwellings wired for up to 9.2 kW without a Surge Protection Device (optional). An ICP (Power Control Switch) is not necessary. Circuit label list still to be fitted. Always have spare holes for future use.