You presumably mean 32A (or 30A) socket circuits - since they can be just as needed on a 30/32A radial as a 30/32A ring final.
Kind Regards, John
TV in bathroom - regs and safety
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Kind Regards, John
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We have had a few instances where alarm engineers would not change there panels as they could not isolate the panel supply and its also a specific requirement for fire alarms. though a key switch is now the required way.
Most fcus for boilers fans etc seem used more for double pole isolation reasons regardless of whether on a 6 amp or 32 a circuit, before the days of fan isolater switches they seemed a lot more common.
I suppose I wasn't thinking of commercial installations where it might not be convenient to isolate the circuit.
What about in a house, though?
They are idiots then aren't they? Every circuit in a house can be isolated either with a MCB or pulling a fuse.
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Flats are a different matter, such as the ground floor with the washing machine socket which remained live even with the CU switched off.
Apparently connected to a circuit in the upstairs flat, and they had been paying for the electricity for years without realising.
Probably still are.
so don't use a typical BS1362 fuse in the FCU. Out of interest what is a non typical BS1362 fuse ?
The Live is removed that way, the Neutral remains connected. With the Neutral still connected the circuit is not isolated. ( that is my opinion )
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There was a comment about historically, "lighting" circuits have always been protected by 5/ 6A devices.
In the 13th Edition (and prior, AFAICT), the rating of 1/.044 (0.96mm²) single and multicore cables was 5A.
In the 14th Edition, the rating of 1/.044 (0.96mm²) single core cables was increased to 13A or 12A twin core (with or without ECC).
Looks like there were big changes in assessment of current-carrying capacity between the editions. Under the 13th, the smallest cable size is matched to the smallest fuse size. Under the 14th, this capacity was upped so that the next smallest fuse size could also be used without upgrading the cable.
Historically, 5A was chosen as a fuse size because the allowance was 100W per fitting (although many chose to fit 150W) and 5A= 12 x 100W at 240V (historically, both floors were wired with one circuit).
In the 13th Edition (and prior, AFAICT), the rating of 1/.044 (0.96mm²) single and multicore cables was 5A.
In the 14th Edition, the rating of 1/.044 (0.96mm²) single core cables was increased to 13A or 12A twin core (with or without ECC).
Looks like there were big changes in assessment of current-carrying capacity between the editions. Under the 13th, the smallest cable size is matched to the smallest fuse size. Under the 14th, this capacity was upped so that the next smallest fuse size could also be used without upgrading the cable.
Historically, 5A was chosen as a fuse size because the allowance was 100W per fitting (although many chose to fit 150W) and 5A= 12 x 100W at 240V (historically, both floors were wired with one circuit).
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I have known "engineers" (not just alarm ones) be adamant that they want local isolation for the bit of kit they are working on. They don't want to responsible for isolating a whole circuit in case something has a hissy fit when the circuit is re-energised.
I've had some alarms do this and Sky boxes too.They have both needed resetting before they would work again.
What does it say on the front of your copy, Winston - surely it must be the same?
Has it occurred to you that to insist something must not be done because it might be removed from the regulations in the future is, shall we say, a little light on rationality?
Yes, that's fair enough and, as I said, some things are a good idea.
I just don't think it should be a Manufacturer's Instruction if it is not electrically required.
They should state the real reason and then we would know; not pretend things like fans need it.
That leads to stupid suggestions that we can then work on them with the lights on
I agree with that.
The modern way for alarms now tends to be a 3 amp fuse module and a double pole key switch module in grid.
And you were wrong to say that.
Supply needed in loft and there's no accessible "power" circuit.
Or, as I've witnessed recently, supply needed but the power circuit is inaccessible because of the use of the modern crap non-liftable flooring. In this case, to have accessed a "power" circuit, it would have meant making swiss cheese of the flooring in a new build - the cable would have needed to go through half a dozen joists and at least one noggin, and that would have needed quite a lot of holes cutting and fixing up again afterwards.
You can argue as to whether ripping a house apart (or rather, avoiding the need to rip it apart) constitutes a "good" reason, but it IS a reason.
Presumably only a small load is required in the loft. Therefore I repeat that there is never, ever, a reason to put a 13 amp socket on the lighting circuit. For a small load you can use a clock connector, a BS546 2 amp socket, or a BS546 5 amp socket.
What if the item you want to supply has a wall wart power supply? Not all, but some boosters do.
Would you then make up a flying lead with a BS546 plug on one end and a BS1363 trailing socket on the other?
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