Dangerous electrics

ValHaller

AndyPK wrote: »

It's a false economy fitting Mcbs to that.
Or spending any real money on it.

It does at some point need a new cu, but at a sensible price.

I prefer cartridge fuses as a replacement on those.

If the rest of the installation is serviceable, there is nothing false about the economy. There is no immediate need to change one of those if it has MCB's or Cartridge fuses. The time to change it is when the installation as a whole needs a rewire.

If the average cost of a rewire is £2500, then £50 on replacement fuses is 2%. Worth while if you can postpone a rewire for 18 months. If you are paying 20% on your highest APR credit card, it will pay for itself in 3 months!

AndyPK

If there is nothing wrong with the installation, then fuses will not be blowing, therefore they can be left alone.

I would hope that a rewire is not required, and a new CU with RCD/RCBO would tidy it up and provide RCD protection.

It looks like that one fuse holder has overheated and hence no longer used. No point spending any more on that fusebox.

geordiepaul2001

Thanks for the replies guys.
The electrician that came out removed the fuse as he said it used to belong to an electric shower (we replace with thermostatic).

ValHaller

AndyPK wrote: »

If there is nothing wrong with the installation, then fuses will not be blowing, therefore they can be left alone.

I don't accept that either. It's like saying that if there is nothing wrong with your driving you don't need seat belts,

AndyPK

Not really. It has fuses.
But you seam to want to change them for no reason.

ValHaller

AndyPK wrote: »

Not really. It has fuses.
But you seam to want to change them for no reason.

Rewireables are not the best at clearing faults.

The fuses are the functional core of a consumer unit, changing them is the most effective way of improving the performance of your consumer unit

AndyPK

Please explain further.

Wi88le

geordiepaul2001 wrote: »

Thanks for the replies guys.
The electrician that came out removed the fuse as he said it used to belong to an electric shower (we replace with thermostatic).

It was safer with the fuse holder in place without fuse wire in it rather than having the connections showing through from behind, that spare way could also have been used to feed the sockets you mentioned earlier.

Nb There may be asbestos linings in the fuse carriers and there is discolouration around fuse 1 from when there was a shower there, possibly from excess heat, but holder shows no sign of heat damage and the terminals behind look ok, not flagged up by the electrician?

ValHaller

AndyPK wrote: »

Please explain further.

What do you not understand?

Wi88le

3036 Rewirable fuses vs circuit breakers from a time/disconnection point of view.

It all comes down to how the fuses or circuit breakers operate under fault conditions, wether that be short circuit or overload conditions, breakers and fuses all have different characteristics.
Rewirable fuses are still compliant with the current regulations, unlike some circuit breakers.

A 3036 rewirable fuse normally blows quickly under short circuit fault conditions as the current from the fault is sufficient to blow the fuse, however fusewire requires a much higher current than its rating to blow under overload conditions, look at the time curve graph for rewirable fuses...
http://wiki.diyfaq.org.uk/index.php?title=Fuse

So for a 5a lighting circuit...
13A for 5 sec
18A for 1 sec
24A for 0.4 as required by current regs in most cases domestically) *5 times the rated current of the fuse
32A for 0.2 sec
45A for 0.1 sec

Now look at a type b 60898 circuit breaker...
http://wiki.diyfaq.org.uk/index.php?title=MCB

For a 6A breaker
30A to trip from 0.1 to 5 sec ( not as odd as it sounds )
So at 30A or above disconnection in 0.1 sec due to magnetic strip operating.
Small overcurrent allowed,6.65A without trip however above that the thermal contact will operate and trip instantly at 9A

So yes the breaker performs better but in some aspects only marginally so, it is however when an rcd or rcbo is added that the benefit is really seen as faults are more likely to be detected and disconnection time is now in milliseconds and milliamps not seconds and amps.