Hi all,

My house is one that had a double storey extension built about 10 years ago, and a CU was installed to power that side of the house, which consists of a bedroom, bathroom and the kitchen. The rest of the house is using an older style fuse box that has the rewireable BS3036 fuses. (2 x 5A, 1 x 15A, 1 x 30A)

Upon checking the fuses one day I noticed that the 15A fuse was wired using a single piece of 2.5mm copper wire

Naturally I thought this was incorrect and hazardous so I replaced this with 15A fuse wire which is when the fun started. Now if I have too many appliances on at the same time, e.g. oven, microwave, tumble dryer -- the fuse will blow and require rewiring. This is getting to the point where it's inconvenient and annoying and I am thinking that maybe the newer CU is wired up to the single fuse which is why it keeps overloading and blowing. The fuse is also extremely hot when it does go and I have to let it cool down before I can take it out.

My question is what should have been done when the CU was installed so that it was done correctly, and how much of a job is it as money is a bit tight at the minute!

Thanks for reading

Fuses or MCB's are selected to protect the cable. To use a bigger fuse would likely need a heavier cable so not much one can do.

It was standard to have a 15A fuse to feed the immersion heater often with an option for switching it on and off in the kitchen. I would guess this cable has now been used to power the new consumer unit. Clearly not good enough.

My parents had a new kitchen and because the house electrics were old a steel wire armoured (SWA) cable was run around outside of the house to new consumer unit.

Step one is to find out what cable has been used. Maybe the guy just did not bother buying right size fuse and cable is man enough?