A Day in the Life of Sparks #3 – Replacing a consumer unit

A Day in the Life of Sparks #3 – Replacing a consumer unit

By on Oct 23, 2015 in Consumer Unit | 2 comments

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.


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  1. Interesting article, thanks. In a domestic house do you need twin and Earth in new colours for ring mains and rated eg 2.5mmsqd as in the UK?

    Keith's coming to Spain

    March 10, 2016

    • Neither Twin + Earth or ring main circuits should be installed in Spain

      Tony Poole

      March 10, 2016

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