All our freebies were the 11W stick type CFLs - the worst type that existed - that took ages to light up and had a horrible pink colour. At least roun d here, most people got their ideas of CFL from those. The 20W spiral types are much better. We go a lot of those cheap, but they were not free. I still have an old 11W stick type under the under-stairs cupboard - it is utterly feeble !
Simon.
No wonder they gave them away, they probably would have had trouble selling them!
My guess is there are still thousands of the freebie CFL's stuck in boxes in cupboards throughout the land.
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I've been thinking recently that with all the 5 V DC wall-warts in the house, it would be nice to have a 5 V DC wiring system alongside the
240 V DC one. Obviously the plugs would need to be very different for safety.Ideally, one circuit on the existing CU would keep a battery charged, which would feed a subsidiary 5 V DC CU, which would feed the special sockets; this would have the effect of UPS for all the electronic equipment.
And the wires to supply 5v +/- 0.1v would have to be incredibly thick!
Modern switched mode AC/DC to DC converters are so efficient these days that it isn't even remotely worth considering. Increasingly in hotels you do find wall sockets for mains with a USB charging point built in.
Distributing DC is a mugs game. If Edison (DC) had won out over Tesla (AC) the highest skyscrapers would be no more than 6 stories high!
Yes - I'd go for 5 & 12v though. 5v by usb, 12v by the ubiquitous round dc plug.
Battery is a waste of money. Also at 5v its best to have local supplies to minimise copper use. Put a 5v ring circuit in each room, not connected to anything else, and feed it with a local plug-in wallwart (or 2 if needed).
NT
With CFLs manufacturers mislead re the light output. With LEDs they frequently lie about longevity.
And the light output of a CFL after 6 months use?
En el artículo , Adam Funk escribió:
replace a few mains sockets with ones that have a USB charger built in, e.g. ebay 161773080872
no separate 5v supply or extra wiring needed (and good luck trying to distribute 5v DC around a house without voltage drop rendering it useless)
You could always send it down the copper piping :/
NT
If my maths is right you might be surprised:
Assuming you are feeding the 5 V in at the upper limit of 5.25 V and the minimum allowable at point of use is 4.75 V you have 0.5 V to play with. Assume 1 A load (5 W) the maximum resistance is 0.5/1 =
0.5 ohms. 2.5 mm^2 has a resistance of 7.5 milliohms/m so 0.5/0.0075 = 66 m.Halve that for a bit of margin and allow for 2 m of "bell wire" from the wall to device.
En el artículo , Dave Liquorice escribió:
You neglect the voltage drop at each wall point where a device is plugged in. An iPad can take up to 2A.
50m 2.5mm^2 at Screwfux is 30 quid, plus the cost of faceplates, back boxes, plus the cost of labour to rip up floors and lay the cable, chase walls, sink backboxes, make good, connect up.Your 'half for margin' at 33m is only going to do one floor of a typical house, so realistically you'll need a 100m cable reel at 50 quid.
Waving my hand in the air, for a house with 10 rooms, let's say 50 for cable, plus 10 quid per socket (backbox, connectors, faceplate) = 100, plus labour - optimistically, 2 days at 300 quid per day - a total of
750 quid.And that neglects the 5v power supply which is gonna have to go somewhere, is a single point of failure and will need to be prtty chunky to deliver the anticipated load - say 2A per room x 10 = 20A. (Maybe use a PC PSU, though those need a certain minimum load to regulate properly.)
For that you could install 100 replacement double sockets with USB ports built-in with minimal labour and mess. Going with two per room in the example above, that's 2 x 10 x 7.50 = 150 quid with 600 quid and 2 days left over to spend on $BEER.
I know which I would go for :)
You'd need to allow for a bunch of loads, mostly well below 1A, but as you say its quite doable. But its pointless to feed from a central supply when you can just plug an otherwise unwanted 5v wallwart into a local ring. Near zero cost upfront, near zero cost when it dies. You can also use all 3 cor es in cables, if you buy 3 core and aren't also distributing 12v.
NT
If their quiescent power is ~1/2 watt each they will cost you ~£50 a year even when you don't use them.
I wonder what fire risk they present, where do they dissipate the heat they must generate to? What's the de-rateing factor needed for the cables next to the additional heat source?
And I, a plug in USB charger like the ones that come with most phones and tablets.
En el artículo , dennis@home.? escribió:
They switch off when there's no load on them, denise.
How many are you fitting in your mansion in Tipton, then?
0.5/0.0075
No that's was included in the 50% derating that you have snipped.
Sounds like you are also assuming a ring topography and all the load current flowing in one cable. For that reason, ie excessive voltage drop, the wiring would be radials.
etc. I didn't say it was particulary practical, just that cable length is not the limiting factor that you implied.
And the required filter components leaking power? Not only L-N but also L-E, raising the general level of earth leakage current and "pre-sensitising" any RCD's making nuisance trips more likely.
And what happend to the "unplug/switch off at the socket when not in use" mantra?
Yes dear, they have switches on them do they?
Didn't you claim to have kill filed me? Please do as you aren't clever enough to read what I post.
En el artículo , Dave Liquorice escribió:
How many of your wall warts do you switch off at the socket, as opposed to just yanking the cable out of the device?
Are you one of those anal retentives that unplugs their TV every night, or do you leave it in standby?
50p not £50
you can't work that out?
nothing
NT
filter components don't consume power, they consume a tiny bit of reactive current
L-E caps are optional
people ignore it, but it appeases the greens.
NT
All of them.
It is worth measuring the standby power usage of your TV. It could be as high as 20-30W to run the TDTV decoder in the factory defaults for some models. The digital decoder may otherwise be left on all the time.
Well behaved kit tends to have standby in the 200mW region.
If you can reduce your base load by 10W then it is a worthwhile saving.
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