Could/Should I replace this old style fuse box??

Jeepers_Creepers

Risteard said:

There's no such thing as an "RMCB". What you are referring to is an RCBO - residual current circuit breaker with integral overcurrent protection. Incidentally, the Wiring Regulations removed the term "MCB" in 2008 - these are now correctly referred to simply as circuit breakers for BS7671 installations.

Thanks. It looked funny as I typed it

Carrot007

I got mine changed. Was not as old, just a plastic box with no rcd though.

Did it with a new kitchen. Not technically needed and the bad kitchen wiring was not in the consumer unit! It was just wired bad at teh other end (the oven was old/damaged and could not be turned off except at the consumer unit! Yes there was a cooker switch. Not sure if it did anything beyond the socket with it! it was wired bad!

Not had a problem since. Couple or trips here and there and with good reason! But nothing in the wiring. (which is hard to get wrong!).

Only compromise was tonot split the lighting circuits as they were unable to determine if they were truly seperate. Still Will all have phones with torches these days if needed!

They did even put in a repalcement for a unused circuit (the old water heater or some e7 thing removed long ago). I turned it on at one point and found it was just going to a floating wire in the loft! Much what I expected from the previous owners! I terminated it in a junction box in the upstairs cupboard when I replaced the boiler (it was a silly place for a boiler anyway!).

Main issue when I moved in however were. One lightswitch had no earth! (Yes I check such things, no it was probably not going to cause any issue). and the proper lightswich in the bathroom! (wetroom with shower and no tanking to be specific, replaced it on day 2 wityh a pull switch as had to repalce the only toilet on day 1 which was more urgent!)

martin2345uk

So the sparky came over today, said yes he can replace it with a modern CU, but that first I would need to get a "Main isolator" installed... apparently the energy suppliers do this, I contacted Shell and they said yes they will do that no problem but what exactly is a main isolator? Sparky tried to explain but I just didn't get his explanation...!!

victor2

martin2345uk said:

So the sparky came over today, said yes he can replace it with a modern CU, but that first I would need to get a "Main isolator" installed... apparently the energy suppliers do this, I contacted Shell and they said yes they will do that no problem but what exactly is a main isolator? Sparky tried to explain but I just didn't get his explanation...!!

Don't know why the sparky couldn't explain it, but it's basically a switch like the main ON/OFF switch in your CU, but external to it. That CU has a permanent live feed into it, so it cannot be isolated. A separate switch (or removable link) outside the CU, possibly even before your meter, allows the incoming supply to be isolated. Such devices have tamper indicating seals on them and should only be accessed by authorised people.

I stand to be corrected, but that's how I understand it, and is how my domestic supply is set up.

Jeepers_Creepers

Could they mean the large fuse that's on the supply side - that isolates the live, as well as providing overall current-limit  protection?

YellowCarBlueCar

He'll be referring to a switch which is fitted between the meter and the fuse box (as is) which is fitted by the DNO.  It means he can switch off the supply to the fuse box to change it without having to tamper with the main fuse which is on the supply side of the meter (which only the DNO is allowed to fiddle with).
No anti tamper seals on the isolation switch as it's put there to be used.