What do you call those new style fuses for a mains circuit?

pinkpinkfizz

Hi,

I have a house about 40 years old which still has the original fuse board/wired fuses.

We had a problem with a bedroom light not working and had an electrician come and fix it. Turned out to be that the previous owners had put in loft flooring and it had been laid over the top of the lighting wiring and when we (thankfully, only very occasionally) went into the loft, walked on the flooring which in turn pressed onto the cables and eventually broke the wires. What caused me to be totally freaked was that the wires were scorched and the fibreglass was also black, where the wires were being crushed!!! now I am terrified that the wiring will catch fire, in the places where it still works but has been under the flooring?? I can't afford to have the electrician come back and rewire, but he suggested that we change our old wired fuses for the new trip style ones. Our old wired fuses never blew. I've been looking online but can't see what I need (can't remember what the electrician called them)

Can anyone help please?

latecomer

If the wires simply broke then they wouldn't blow the fuse. the fuse is there to protect against excessive current being drawn.

you can get circuit breakers that plug into older style fuse boxes like these:
http://www.thefusecompany.com/fuse.php?cPath=58&products_id=413&sid=f48e916969a8986e5a217ed02dcead48

you would need to check it was correct replacement for what you have.

Mutton_Geoff

Replacing the old fuses with new style MCB's (miniature circuit breakers) won't help protect you against this happening again. The scorching happened because the insulation wore through and current flowed in a circuit causing heat to be generated. This would have happened whether you had a 5amp fuse or a 5a MCB. They will only trip/blow when the current is exceeded (they are there to protect the cable, not the devices on the end which is a common misconception).

The next thing to install is an RCD (residual current device, used to be called "earth leakage breakers"). This detects whether all the current going out of the live wire is coming back down the neutral wire and not "disappearing" somewhere (in the UK neutral is essentially at earth potential so any live potential will always try to get to earth). It can sense fractions of an amp (30 thousands of an amp) which is below the sort of current that would kill someone and so they can be lifesavers. Again if there is a live to neutral "short" in your wiring, provided the current drawn does not exceed the MCB rating, current will still flow and heat generated.

Cable is often constructed with the earth wire uninsulated (within the sheath) and in between the live and neutral wires, so left to chance, the live is more likely to short against the earth and trip the RCD if you have one. In this case, they are a good thing.

It sounds like an expert eye should have a look around your system and the person who bodged the loft boarding be shot at dawn. How much do you value your home? A good spark will run through it all in a day and replace your consumer unit with something more modern. They can also use a megger to test any breakdown of insulation that may be hidden under more boards or in the walls.

27col

When I was wiring houses 40 years ago we always used Wylex Consumer Units. They were very commonly installed at the time. If yours is a Wylex unit, it will say so on the front and on the individual fuse carriers. The MCB's shown on the link will fit and are not very expensive. You can get them at B&Q. If you cannot fit them yourself then it would not be expensive to get someone to do it for you. I do not think that you can fit an RCB into the old type Wylex units., so it would have to be fitted externally.
This would not be a job for you.. It might well, not be worth, trying to modernise the existing box, and not much more expensive to get a modern one fitted.
The wiring of that period was Twin +E PVC, the same as is used today, and should not have deterioriated at all, unless exposed to sunlight and/or heat.What you need to do is lift the loft boarding and physically check the state of the wires. If there are any more that have been damaged, then they will need either replacement or repair. A megger test would show if there are any insulation faults, but if there is damage that has not yet developed into an insulation fault, that will only be found by a physical inspection.