We did some work many years ago at a farm, being converted into a religious college , we found one ring main with 10 spurs , of those
10 spurs several had spurs themselves . Eventually we counted 30 double sockets on the whole circuit , fortunately most were buried behind cabinets and other units and unused, those exposed had 5 gang extension bars plugged into them if only 20 % of them were used to full capacity we reckoned the place would have been ablaze in minutes .
Those sockets would have been pretty safe though!
Most tests use automated tools, and are carried out at the consumer unit, so that error would not necessarily have been detected.
Chris
If that was in an agricultural building where no part was used as a dwelling, and wasn't open to the public, it wouldn't have been covered by Building Regulations however.
Chris
No axe to grind there, then. ;-) Some time ago a Corgi registered fitter told my elderly next door neighbour only the likes of him was allowed to fit a new cooker. And hers is electric...
The most common cause of fires in that context is overloaded extension leads. Now the chances are anyone who would attempt to extend a ring or add to it has slightly more knowledge.
Actually, you can only run about 3 sockets at 13 maps on a ring before the breaker will trip.
Surely an extension lead will have its own fuse in the plug or the socket and so would be self limited as to capacity?
The problem is that we lagged behind the rest of the world in upgrading to consumer units that used MCB's. There are still *many* installations where the circuit protection is via a re-wireable (strictly 'semi-enclosed') fuse.
The fusing factor of a wire fuse is 2. This means a 30A fuse will need a load of 60A to blow instantly. It can carry a big percentage of that current without blowing for a considerable time; 100A for 3 secs, several hours at
45A for example.45A current for a couple of hours on a 2.5mm twin and earth cable, where the cable may need de-rating due to installation factors, is a recipe for a fire.
An average factor for an MCB is 1.4; its time/current curves are such that the likelihood of a fire are much reduced.
Chris
Really? Find that a bit difficult to believe now in 2015!
No fuses anywhere;?....
It was the farm house the electrics in the agricultural buildings were round pin rubber coated wire, they got disconnected within two hours of arriving on site , fused by a 6 inch nail
No breakers, old style wired fuses , very rusty
That assumes a level of intelligence that people will actually replace with a fuse and not a piece of wire or a cut off 6 inch nail which i have seen all too often
Until the fuse(s) are replaced with a nail.
As the saying goes, you can make things fool proof. Even idiot proof. But not c**t proof.
Why? It was still possible to comply with the IEE regs using semi-enclosed fuses until 2004!
Until then, an RCD was only needed for a socket intended to be used with an appliance outdoors, such as a mower. This could be achieved by using a socket with an RCD incorporated, leaving the other circuits in the house with just over-current protection.
RCD protection for virtually all circuits has only been mandatory since a
2008 amendment to the regs.There are a lot of houses built prior to 2008 that have not had a rewire since that date!
Chris
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