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andrewpreece
 
Posts: n/a
Default LV Lighting supply dilemma


wrote in message
...
In uk.d-i-y, Christian McArdle wrote:

I would use an unswitched 13A socket indelibly marked "lighting only"

fed
from an adjacent 3A FCU on the lighting circuit. It probably isn't quite
compliant with regs, but it'll be reasonably safe.

The main safety issue is that when the next occupier plugs the vacuum
cleaner or a fan heater into it and the lighting MCB blows before the

fuse,
it will cause the lights to go out and granny might fall down the stairs

in
the dark.

(Not our granny: she doesn't do stairs at all any more...)

Indeed, to make it less likely to pop the MCB under an inappropriate
load, you could do a lot worse than fit a 1A fuse into the FCU. The 1A
will indefinitely feed 300W or more of halogen lighting (no, fuses do
not blow at 1.0001 times their nominal rating ;-) but if some mumpty plugs
in the vac, hair dryer, or fan-heater into the clearly-marked Lighting
Only socket there's a sporting chance that the 1A cartridge fuse will pop
before the 6A lighting MCB. Only a sporting chance, mind, given that
cart-fuses and MCBs have rather different time-to-blow-on-overload
characteristics, and that the MCB will be supplying other lights too -
so might be feeding 5A to other loads on the same circuit which Mumpty
just plugged an electric chainsaw into... but a sporting chance

nonetheless.

HTH - Stefek


Thanks all - I didn't mention that the socket would be in a space above the
top of the airing cupboard ( lined with wooden wainscotting ) so won't be
visible, or accessible easily, so maybe the 13A socket with a Dyno'd
"Lighting Only" label plus a 1A FCU is the way to go. Probably
non-regulation
but I bet there're very few houses in the country that are totally
regs-compliant.
The main thing is that it should be safe and reliable.

The idea of using a different transformer is good, but then these lights and
transformer were bought at IKEA for very little money and it seems a shame
to buy more expensive stuff, also the present TFMR is moulded to the LV
cable.


cheers,

Andy.