Myths: Turning off lights to save power.

[LowGear]

I've seen appliances for 12 and 24 volt but never 120.  Are they out there?

[AdeV]

My preferred solution is to go 120 volts DC for the home.  It requires 4 times the current through your heart to stop it, so is the equivalent for safety as 30 volts AC. 120VDC feels like a modest static shock, it is not nearly so jarring and painful as AC.

The problem with high voltage DC shocks is that the muscles clamp up; so whatever you're hanging onto which is giving you the belt, continues to do so until the fuse goes (which, in US electrical systems, appears to be in the pole transformer or substation....) At least with AC the reversing polarity gives you chance to let go of whatever's zapping you... not that it's any guarantee. I can't remember the exact number, but I'm sure I read somewhere/was told that a current of just 20mA can stop your heart. You're going to get that pretty quickly with AC OR DC...

Edison will win out, eventually.

Within the home.... maybe. For long-distance (like, more than a mile or two) the disadvantages of DC far outweigh its advantages. e.g there's a AC interconnect between the UK mainland and the Isle of Man. There is, however, a 2GW DC interconnect between the UK & France - the longest undersea link in the world... but that works at a rather eye-watering 270kV... touching that would be guaranteed to give you a stiffy, for the 5 nanoseconds before you spontaneously combusted...

[BruceM]

Hi Ade,
I had also believed that piece of propaganda from the AC-DC wars - but when I looked into it I found that it is not based on science.

The "can't let go" current threshold  is again much safer with DC.  Here's a reference with a table showing DC vs AC loss of muscle control threshold, and the required current is roughly 4x as high for DC.

http://www.highvoltageconnection.com/articles/ElectricShockQuestions.htm

Regarding AC vs DC for long distance transmission; 1M volts DC is being used in lots of countries and between countries. The under-sea line between Denmark and Sweden, is one, as I recall.  It eliminates the sync problem between countries power grids, and DC wires can be smaller for the same voltage drop since there's no dead time between polarity changes.  Conversion efficiencies are quite high- comparable to AC.

Westinghouse won with AC because there it was no technology for efficient DC-DC conversion or DC to AC conversion.  For the level of technology of the day, it was a rational choice and it made Tesla's 3 phase motors for industry viable.

Casey,
Lot's of things do work on 120VDC, and many more can be modified to do so.  Bimetal switches can't be used for switching 120vdc, so the classic duty cycle temperature control or thermostat won't work.  What I did for my toaster oven, for example, is to add a MOSFET power transistor for each element, and let the timer and thermostat control only the tiny gate control voltage (resistively derived from 120vdc).  That way the transistor does the switching and everything works nicely. No power supply is needed and only a rewiring of the thermostat and such.  Many things like crock pots and immersion heaters or even hair dryers and coffee grinders, blenders (the last three with brushed universal motors), and soldering irons work fine without modification.  The 120V "universal" motors run equally well on DC, since they are actually DC motors.

I don't seriously think we will have a switchover to DC power anytime soon.  There is a huge vested interest with AC.  More likely DC will happen with independent power systems as it is now for data centers.

[BruceM]

The upside of doing small insignificant things is that if enough people do it and start thinking about what kind of world we leave for the future generations, maybe eventually people will start voting for the better future instead of for their own immediate financial gain or hatred(s).

Pure fantasy. 

[LowGear]

Half full or half empty - I prefer representative democracy.  You do know that direct democracy isn't really that far away.  Now that's going to be a lot of caged monkeys playing video games.

I'm starting to find half cups of wine around the house in the morning.  A half cup of wine in the evening is well within Doctor's guidelines.  And I know what I'll be drinking while cooking dinner.  That's the up side of the half empty world.  It's totally full for the next evening.  I urge you to look for the half full side of the equation whether it's wine or dwindling coal plants.  Am I losing another part of my memory or is my memory taking care of me?  That's a nice up side of something that is going to change and I have little control of it.  Thank you memory.

[guest23837]

I have to admit I passionately dislike the Irish "green" party bunch of one trick ponies. A few years ago they went into a coalition government as seat warmers but the held the balance of power. They started off with petrol is bad diesel is good and Ireland now has about 70% of all cars running on diesel. Now these freaks want to tax diesels to make them unviable. They came up with another spiffing idea, a carbon tax on fuels to be added to the already huge 60 odd percent tax the government takes on fuel including gas and coal. Not having done enough damage they launched into promoting wind generation as a green alternative. Of course the wind can be unhelpful and power is difficult to store but they countered this with another bright idea, have gas and oil fired stations running in case the wind became unhelpful.  Of course Europe, they of renewable energy rules, thinks this is a fcuking GREAT idea we produce some wind energy (most exported to the UK to help them meet renewable power requirements) and run huge power plants as backup. This is cosmetic nonsense the greens have no interest in wave power, hydro power, solar power etc and they have managed to get successive governments to continue with this madness. Juan Kerrs all of them.
Glort is right when he says that the big players don't care about wasting stuff but I think more and more "ordinary" people do care. Recycling is up, repairing stuff is still at a low level but hopefully will become more more prevalent as time passes. I believe manufacturers should be boycotted more until they start producing things that actually last or that can be repaired. The old listers are a great example!

[guest23837]

Ireland brought in a plastic bag tax a few years ago. I went into the shop the very day it started and I was sold a plastic bag with"this bag will decompose harmlessly if buried in soil" printed on it. Bloody great the bag I buy can decompose but the old free one will lie in the hedge for 1000 years, WTF?

Mobile phones are one of the many things that have built in obsolescence apple phones are one example. If the hard sell to upgrade doesn't convince you to change the phone will die anyway. I have a couple of friends that have the latest apple phone because they couldn't possibly live without it. I had a play with them and guess what? They're bloody phones nothing more. I got a new phone at Christmas it cost €140.00 does everything a €1200.00 iphone does but i know many people who wouldn't be seen dead using my phone.

I too am in my mid 50's and I remember valve radios, B&W televisions etc. When your appliance broke down you used to have 3 or more choices, local handy man, main dealer , replace it or live without it. Nothing seems repairable now and young people couldn't care less. They don't know that meat is dead animals that eggs come from chicken etc. These fools ask for celiac food in restuarants not because they have a gluten intolerance but because it's the latest thing. These Penelope Pitstop types really get on my wick.

Luckily there are forums like this, forums where real people repair real things, I have learned a great deal of stuff reading on this site. There are still people making parts in sheds, real craftsmen, there are still people saying to themselves I wonder and what if... How many of the young engineers could cold stitch a cast iron head? All throw away stuff now and whilst I have many Chinese made items in the house and shed Im still wary of the standard. eg I bought a little 2 stroke generator recently it was one of those buy and forget items it had been sitting under a bench for a lifetime. It started but ran badly so I took it apart and it was shipped from new without gaskets on the carburettor. I think the world has to have a glut of those little generators thing is they sell well if they start and produce power. I know the pure sine wave crowd would sneer at them but I have a backup generator for the backup generator for the generator.