Excellent point, and one that i missed in my analysis.
...Because I would have two ends sucking out the heat, not four...
That extra factor that I missed changes the answers. It's always good to learn something new. Thanks!
Or you could just switch to compact fluorescent lights like I have and increase your efficiency four fold. :-)
I have often wondered why automotive headlights are so bright considering the fact that such headlights actually use less power than the two 100 watt light bulbs I have in my bathroom. Obviously, the fact that headlights are halogens has something to do with this. But even back in the days when regular incandescent headlights were the industry standard, they still seemed much brighter than regular household lights of equal wattage. I guess the best way to test this assumption would be to take a 12 volt RV light bulb and compare it to a 120 volt (or 240 volt if you're a Brit) light bulb of equal wattage.
Robert
You'll do even better if you replace the whole thing with low-voltage halogens...
Automotive headlights are *reflective* (like the little halogen downlights people use these days).
The reflector (mirror) at the rear reflects all light produced by the bulb filament forward - unlike your standard house light which radiates in all directions.
This is the main reason modern "high-efficiency" houses use strategically-located halogen downlights instead of conventional bulb-and-socket lights.
Cameron:-)
------------snip-------------------->
---------- Right on! Also things like teakettles and toasters are slower A 3000 watt element beats a 1500 watt element any day when one wants a "cuppa". However typical 120V outlets, lamp sockets, etc are somewhat cheaper (in quality as well as in price) so that is a counterincentive to change as one looks at the immediate capital cost vs the long term cost. (this has spread to utility deregulation and its effect on long term planning). However there has been a certain tendency to the "brick outhouse" mode of thinking where, "if it can't be run over by a tank without damge, it is too bloody flimsy " :)
Not a Brit and not a Yank
-- Don Kelly snipped-for-privacy@peeshaw.ca remove the urine to answer
considering
Interesting point. I guess this explains why a milliwatt laser can burn your eyes out while a milliwatt light bulb can barely be seen at all. This also explains why the voyager spacecraft can get by with a 21 watt radio transmitter despite being billions of miles away from earth.
Robert
So exactly *why not* wire the whole house for 240V? Does the NEC permit it?? Then the US would be in line with the rest of the Modern World (sort of.. ;-)
The US plug/sockets I've seen would be quite capable of being safely run at
240V and the wiring insulation would be fine. There could be a chance that someone might plug a 120V appliance in - for a few milliseconds at least - but at the end of the day, 240V certainly makes more sense... from a rank outsiders' view.Cameron:-)
If you wired the whole house for 240, you would cut the total number of permissible circuits your service panel can provide in half. You would need to add a sub panel to end up with the same number of circuits as would be allowed on a single panel feeding 120 volt circuits. None of the 120 volt devices you already own would work.
No, you can't wire a 120 volt receptacle with 240 volts - you have to use plugs and receptacles listed for 240.
No - see above. 120 and 240 volt receptacles have different physical layouts, so a 120 volt plug won't fit in a 240 volt receptacle, and vice-versa.
Perhaps in a theoretical sense there are some arguments for it making sense - but in a practical vein, it would make no sense to convert the system to all 240 here, just as it would make no sense to convert from 240 to 120-0-120 elsewhere. And you haven't even addressed 50 Hz vs 60 Hz ...
There is certainly no technical reason you couldn't but when you consider US citizens would immediately have to throw away a few (hundred?) billion dollars worth of appliances it isn't likely to happen.
Not really. "They" might bring a 3 wire circuit into a double box. The box could supply one duplex 240 outlets and one duplex 120 outlet. I haven't seen duplex 240 outlets but they could be made as cheaply as the 120 volt outlet.
The 3 wire circuits would not consume any more panel space than separate 2 wire circuits. When you WANT 120 volt outlets the wiring at the outlet is a little more difficult but the wiring in the panel is a LOT easier: there would only be half the number of WHITE wires to connect - for some reason panels often don't have enough screws for all the white wires and ground wires needed.
I understand that Canada is big on 3 wire circuits running to duplex outlets. If you live there you can cheaply replace any duplex 120 volt outlet with a single 240 volt outlet. Were that to "catch on" you might even see special "duplex" outlets with one each 120 and one each 240 volt. With good design, it may be possible to wire such outlets nearly as quickly as a string of 120 volt duplex outlets.
UK building regs require a proportion of commonly used rooms in a house to be lit with high efficiency lighting. We define that to be at least 40 lumens/W (including control gear losses), and no filament lamp can achieve that.
It would not make sense to have ONLY 240 volt outlets for many reasons. BUT a mixture of 240 (both 2 and 3 wire) and 120 outlets might "catch on" IF some of the power hungry appliances start to be offered in the 240 volt version.
Since we are talking "pie in the sky" here, it might be "reasonable" to have lower power non-polar 120 volt outlets derived from a transformer with a center tap. These would only have 60 volts to ground. These would be perfect for lamps, "wall warts" and outer low power junk.
Power hungry equipment is already 240v but the trend is to make equipment that isn't that hungry. With the exception of electric space heaters there are not that many power hungry things in a home. Walk around and count up the things that use more than 800w. I bet it isn't more than a couple things out of the hundred or so things with a plug on them.
Why? Or maybe you mean energy hungry, which is a different thing?
You might like to consider the appliances you are missing out on too. For example, I doubt that my microwave oven, at 2.65kW according to the rating plate, is even available in the US, whereas it's a common model (or at least, very common feature set) in Europe. Neither would my 3kW teakettle be available in the US.
------- The 3 wire outlets may or may not be supplied from different legs (although with a typical panel this is simplest). The regulations call for split outlets (i.e. each half on a separate breaker) in kitchens and other high load areas so that the possibility of putting the kettle, toaster and coffee machine on the same circuit at the same time is greatly reduced. However, if one were to also have a 240V outlet, then the breakers would have to be two pole or ganged so that tripping one 120V circuit would trip the other- defeating the purpose of the split receptacle. I would expect that US codes are similar to Canadian codes.
Another problem is that where 120V equipment dominates, the mass production economics would not encourage 240V kettles, toasters, etc.
-- Don Kelly snipped-for-privacy@peeshaw.ca remove the urine to answer
Not true on that score... You would obviously be surprised at the amount of gear out there (not made in the USA) which is designed for 220/230/240V operation for the European and AustralAsian markets.
Some of this equipment, including *all* PCs, *all* Home Entertainment,
*most* Whitegoods, etc. etc. contain switch-mode power supplies designed to operate fine from 100-240V 50/60Hz. Some of this stuff is either switch-selectable or straight auto-ranging.First off, have a look around your own house and see how much cannot be made
240V compatible. ..And for the gear that is 120V only - you can buy plug packs for that.Cameron:-)
We're talking different things. If the whole house is wired for 240, there are no 120 circuits. Cameron's post, to which I was replying, spoke of 240 at the receptacles, so the one duplex 240 and one duplex 120 at the box scenario you describe is not germane to that.
HOWEVER - I think my answer may be wrong. UK folks will know - but I just realized I was thinking of interrupting 2 hots with the breaker. In a 240 UK system, does the breaker interrupt both conductors, or is a single pole breaker used? Is one leg hot and the other leg grounded?
Dunno about the UK system, but the Oz/NZ Mains Earth Neutral (MEN) system has "one leg hot and the other leg grounded" - at the switchboard.
I suppose you could do it either way - if you really wanted a 120V service as well, you could have dual-pole breakers for each circuit.. remember that that we are not talking factories here - most houses have only two or three general power circuits.
BTW, could someone please explain to the curious why a US socket-outlet is
*not* suitable for 240V? The pins and pin spacing is not different to ours and plastic is plastic..Cameron:-)
You would still need to buy new power cords and receptacles. When you are talking about electronics it would take 100 years to get back the price of the plugs alone with the meager retirn you get from I2R savings. To start with we have twice as much copper in the wall so that loss isn't that great. The system IS designed to work at 120v and double the current. Of course in the winter there is virtually ZERO saving since that "wasted" heat is going in a house you are heating anyway.
Of course it is true - you missed his point. It doesn't matter what is available to replace the appliances or devices, the owners of 120 volt stuff would be forced to throw it away if they had no 120 volt circuits.
Almost 100% is not readily convertible and would have to be replaced. Or - you personally can provide us with the "plug packs", so that we bear no cost. :-) Oh, one more thing - you'll need to provide us with the funds to rewire all the
15 amp circuits to #12 wire; to replace all the old 120 volt receptacles with 240 volt receptacles; and to install new wiring, a new box and an additional 240 volt receptacle for each and every duplex 120 volt receptacle we replace. To say nothing of the dimmer switches, GFCI's, doorbell and HVAC transformers, fire alarms, burgular alarms .... and so forth. I hope you have very DEEP pockets!! :-)
It would work at 240v but we have standards. There are 240v receptacles, even duplex 240v receptacles that would be a direct swap with the 120v unit but we would never allow the industry to use a 120v receptacle on a 240v circuit.
PolyTech Forum 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.