We have been called in because the customer had an electric shower replaced and he had to replace the fuse on regular basis after taking a shower longer then 5 minutes. Now although a lot of people say that a shower can be replaced by a plumber or Handyman if its like for like replacement, We would strongly disagree. The shower that was there last time was most likely 7.5kW and was replaced with 8.5kW. The brand and product name was exactly the same but one was purchased 3 years earlier so to untrained DIYer it would look like its a like for like replacement but small print would indicate that power rating is higher.
Because the fuse was replaced on regular basis, the fuse holder started to deform and highly heated plasma was forming inside the fuse box creating smoke and started to melt the enclosure. The client decided to replace the fuse box and fit appropriately rated shower.
Before removing the fuse box its important to check if there are any issues in the individual circuits, which we checked. We found that the main boding to water pipes was missing. We knew that the replacement consumer unit will need longer Consumer Tails. We can’t access the metering equipment to replace the whole length of cable so we fitted an Isolator switch and extended Consumer tails from there. We then fitted the new shower and bonding to water.
After Isolating the supply and preparing the consumer unit, we disassembled fuse box, fitted the new one, then done dead testing on all the circuits. Once satisfactory we switched power on and done remaining tests, Created a certificate and notified the building control.