Yes and no. If the 1A mcb protects against long term small overload then al l is well, and that's not challenging nowadays. The greens should love it a s it limits use of halogens.
I think those jboxes are a bit dated now
NT
The attribution is wrong, that was a reply to me. But why assume it isn't in an airless place, since cables often travel in conduit, trunking, behind insulation or under plaster? And sometimes with many similarly loaded cables.
Given the smallest TW&E is 1mm, I'm not quite sure what option you'd have?
Think it's fair to say LEDs are being improved all the time, and are getting cheaper too. So unlikely anyone would go back to halogen if happy with today's LEDs.
Not even I've managed a lighting load of 3 kW on a single circuit. But then I did have the sense to fit an adequate number of lighting circuits.
Those are impossible questions to answer without exquisitely detailed knowledge of the actual installation - i.e. the length of the circuit, and what de-rating factors apply all the way along it.
However you can look at it the other way.
If you start with the tabulated ratings for the cable:
You will note there are a number of different maximum current ratings specified for 1mm^2 T&E. They change depending on the installation method.
Installation methods that allow for good cooling of the cable, like being buried directly in masonry, or being clipped to a surface in free air (both method C), will allow the fastest rate of heat loss from the cable and hence the highest current.
The current limits are set empirically such that the temperature of the cables conductors at that load will not exceed the temperature at which the insulation would either be damaged, or at least start to experience accelerated ageing. For normal PVC clad cables the limit temperature is
70 deg C.The temperature of the cable actually achieves will be proportional to the power being dissipated in it. That will be dictated by I^2 r. The squared term in there will mean that the temperature rise will be non linear with the lions share of the rise happening near to maximum current load.
Perhaps not the worst, but the guideline is to assume the higher value of either whatever is fitted to the actual fitting, or 100W.
So you would not normally design a circuit with more than 13 lamp fittings per circuit if protected at 6A.
Just done a rough calc. of my downstairs circuit: 11 fittings, total load
80W for 19 lamps, so a third of an amp. Allow for a PF of about 0.5, the 6A MCB should cope, as should any 1mm conductors! Of course, if someone were to fit 50W halgens...!
that made sense in the days of filament lamps. But no longer.
NT
You would still be absolutely fine ;-)
Perhaps, but the guideline is still the same.
Some folks still use filament lamps...
not exactly news :)
NT
En el artículo , John Rumm escribió:
I've got enough stockpiled to see me out :)
Me too. Although I actually bought and fitted some LED GLS "bulbs" for the first time last week.
I bought a good load when CFLs were the only (heavily promoted) energy saving candidate.
I have managed to find a number of "good enough" LEDs now to replace incandescents in many applications. So I may end up with more than a lifetimes supply ;-)
If you're not too worried about lu/W, Screwfix has some 9W, 807lu GLS, E27 or B22, warm or daylightish, for £7.99 for 5 last time I looked.
Don't be put off by the "60W equivalent figure of merit". That's based on the American 120v higher lumen output tungsten GLS lamp which gives noticeably more light than the UK and European 240/220 volt incandescent GLS lamps (around about the same as a 240v 75W 1000 hour tungsten GLS lamp).
These shorter, thicker filament lamps can be run a few tens of degrees hotter without compromising life which enhances the lamp's efficacy which is further enhanced by the fact that the Yanks are prepared to trade off a bit more life against even greater efficacy (750 hours versus our 1000 hour lamp ratings) by running the filaments hotter still.
Are you saying there are actually LEDs around that produce more light than the equivalent figure given on the packaging?
The only reliable "Figure of Merit" is the Lumens output. Our 240v 1000 hour rated tungsten filament GLS lamps produce nowhere near the 807Lm normally claimed for the "60W equivilent" (an American standard). In wattage terms, a more accurate comparison would be the 75W 240v 1000 hour lamp for customers in the UK (which offers just slightly more lumens than the 810 figure usually quoted alongside the 60W equivalency figure.
In short, the benchmark figure of "60W" is based on the higher efficacy American lamp, not the lower efficacy UK version. This has always been the case with all such "60W"/810Lm LED lamps which equates to a 240v 1000 hour lamp wattage somewhere around the 72W mark (if such a lamp were manufactured - the rather uncommon 75W 240v 1000 hour lamps are just a tiny fraction brighter).
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.