Spur off of ringmain - whys it allowed!?

I could understand the ins co wanting copex but what justification would they have for insisting on larger CSA's?
 
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I could understand the ins co wanting copex but what justification would they have for insisting on larger CSA's?
One can but presume that they are wanting lower conductor temperatures - but even the 70°C which might (occasionally) be achieved by using the 'normal' CSAs is surely not going to set fire to anything?

Kind Regards, John
 
I think that temperature is rarely achieved but even if it is, it would not be an issue. A circuit that meets the standards of 7671 is over-engineered.
 
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I think that temperature is rarely achieved but even if it is, it would not be an issue. A circuit that meets the standards of 7671 is over-engineered.
Exactly, so why these insurers wanted to dramatically further over-engineer something that was already over-engineered is really anyone's guess. However, I can but presume that it must be related to a (IMO misguided) desire to get conductors even cooler, because I certainly can't think of anything else that could have been in their minds!

I would think that it would be a good reason for seeking a different insurer!

Kind Regards, John
 
What cable do they want for a shower circuit?
Good Question! "Two sizes bigger" than 10mm² is 25mm² (necessarily singles) - which, apart from anything else, might prove to be a problem in relation to what it was being connected to!

Kind Regards, John
 
Nucking Futs!

They would be hard-pressed to insist on implementing this as they would effectively be saying we cannot accept a 7671-compliant installation for cover.

As you say though, customers will vote with their feet.
 
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Nucking Futs! They would be hard-pressed to insist on implementing this as they would effectively be saying we cannot accept a 7671-compliant installation for cover.
They're obviously free to insist on whatever they want, and that includes requiring more than satisfaction of the 'minimum requirements' of BS7671. However ....
As you say though, customers will vote with their feet.
Hopefully ... provided that most/all insurers do not take the same position in relation to thatched properties!

Kind Regards, John
 
I would like to see the insurer get three 6mm² cables into a back box and connect them, it can be a struggle with 2.5mm². However I have used 6mm² on a ring final with a 32A MCB, and no sockets direct on the ring, all sockets were spurs from JB's in the ring. The circuit was around a warehouse, they needed sockets for cleaning machines, spaced around the walls, the area was huge so using 6mm² SWA around the loft space with drops in 2.5mm² to each socket kept the volt drop down.

I know we can get 16, 32, 63, and 125 amp plugs, but there are very few plugs where there are fuses in the plug, there are 15A plugs where the pins are fuses were used a lot for reduced low voltage, seem to remember two plugs one with and one without fuses and two sockets, the socket for unfused plugs would take the fused type but not visa versa.

I remember a workshop being wired with a 110 volt (55-0-55) ring with the Reyrolt sockets, and some one quoting to modify to new yellow 16A plugs and losing money because every socket needed a twin pole 16A MCB in the box.

Today the ring final is only really used with 13A sockets as the other fused plugs have gone.

One thought however comes to mind. When using a grid system with a 13A socket, switch and fuse holder in a double gang plate, so you can extend to more sockets which side of the fuse would you put the local socket?
 
Good Question! s"Two sizes bigger" than 10mm² is 25mm² (necessarily singles) - which, apart from anything else, might prove to be a problem in relation to what it was being connected to!

Kind Regards, John
Ah this was a while ago, I'd say about 1990, there were 2 showers but they were Gainsboroughs, 6 or 7Kw and I'm pretty sure we used 10mm². all the sizes were specified by the insurers, a list of cirrcuits and calcs was put to them and they amended upwards. The biggest shock to us was the feed to the pool house, they insisted on it being oversized in the event that it became heated at some future date. 25mm² and 60A isolators seemed a bit silly for a couple of 3HP pumps. fortunately it was only 10m or so.
Ever tried wiring a ceiling rose in 2.5?
The big problem with thatched buildings (according to the owners!) was finding a Co who would put the cover in place.
 

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