electricity in homes

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Conrad,

You pay for the amount of energy used.

energy = voltage * current * time

So if voltage or current of time is zero then the energy used is zero.

Another way of looking at this is: energy/time (energy per unit time) = voltage * current = power Power is the rate of flow of energy (per unit time).

Remember, you pay for the amount of energy used. It's as simple as that.

The voltage is always there at the outlets (120V is the USA). The amount of current that flows depends on what is plugged in and whether it's turned on or not, so an appliance that's plugged in but not turned on will draw very little (if any) current -- thus the energy used (over a given amount of time) is very little (if not zero).

Some commonly-used units: energy is expressed as joules or watt-seconds or kilowatt-hours power is expressed as joules per second or watts or kilowatts voltage is expreseed as volts current is expressed as amps

Bob

Circa 6 May 2007 13:21:45 -0700 recorded as looks like conrad sounds like:

So then it follows that if you remove the load, you stop utilising current, and thus are using no power. Are you with me?

Let's tackle that misconception first. You most certainly do have the potential for "pushing a charge across a conductor" when you use the AC provided to your home. How else would any of your electrical devices work?

You absolutely do have a varying amount of current being distributed to your home. The way you use that current determines how much you use.

Completely wrong. It's correct to say that the amount from the powerstation *must* vary in accordance with the demands of the load. If it doesn't, imbalances begin to wreak havoc on the grid.

So, you must change your conclusion that you cannot control the amount of power you use in your home. Few things in life are so completely under your control.

I think you're missing the underlying point.

The talk now is of unplugging unused devices because a lot of things nowadays draw some current even when turned off, and those miniscule amounts of current add up when multiplied by so many devices.

So that battery charger draws a bit of current even when no batteries are in the charger. That ac adaptor that you run your mp3 player at home draws a tiny amoung of current even when you aren't using the mp3 player with it. That tv set, vcr, dvd player, cd player, stereo and whatever else that can be turned on remotely draws a tiny bit of current so long as it's plugged in, because it needs a tiny bit of current to run the circuitry that will take the signal from the remote and turn on the rest of the unit. Some devices use a tiny bit of current all the time in order to keep settings. So if you unplug it each time, you'll have to readjust things each time you plug it back in.

This isn't that far from the old tube sets that were "instant on". They could turn on fairly fast because the tube filaments were powered up all the time, though usually at a reduced voltage, so they didn't take nearly as long to warm up and give you operation.

But, these things are now pretty common place. I've even seen equipment that is not remotely controlled, yet the power switch is on the secondary of the power transformer, so it too draws a miniscule amount of current whenever it's plugged in. (The reasoning in those cases is likely because it's easier for the designer to have the switch control the secondary voltage.)

This has nothing to do with some complicated attempt at understanding it. Connect something to the AC line, and it will draw some current. Do it enough times, and we have enough junk nowadays that it is pretty common, and it can add up.

Michael

WOW~!

JeffM wrote in news:1178485198.066459.295170 @y5g2000hsa.googlegroups.com:

Unplugging equipment has no discernable effect on power usage if the equipment's power switch does shut down primary power. A lot of consumer stuff uses small amounts of power because the power switch only switches off the display, lights, motors while the electronics may still be running, or power supply still using current.

If it gets warm when it is off - unplugging or adding a switch may be worth doing. Each individual item's consumption is negligible, all together, over time it can be significant.

Some items are better than others - a clamp on ammeter and way to get to one supply wire will tell you which ones waste the most power or get one of the plug-in electronic watt hour meters - they can be calibrated to tell you what an item is costing you to leave it plugged in.

A switch on your hot water heater may easily make a bigger difference than all the little gizmos combined. I found the long piping run from the water heater to the kitchen sink was costing me big time (even insulation doesn't help that much when the pipe itself is cold). I switched to using a large SS pot to wash dishes in and heat the water on the stove - If it gets cold while I'm using it I can reheat it just enough.

Modern conveniences like clothes dryers and dishwashers really suck down a lot of power or heat energy.

Range/stove insulation can often be improved by taking off the back and checking the condition or looking for hot spots while the oven is on - some un-face fiberglass saves money there - and double in summer. Oven will maintain temperature better too.

News==----

We live off the grid with solar panels charging batteries followed by an inverter. You really learn what wastes power.

I live on the grid. I admire those that manage their own power.

An express view satellite receiver uses 14 watts when operating. It also uses 13.5 watts when it is turned off.

Many electronic items today only have a switch that makes the consumer think they have turned it off. Simply good PR.

News==----

In Winter, this is not of much concern to me. The convenience is additive to the tiny house heating. The reduction in thermal shock to electronic circuits is also an advantage. In Summer, I tend to turn them off completely. I have rearranged each room with an earth leakage safety cutout and a single switch (easily accessible) to cut all power to that room. I have a very old house with only one outlet per room, and most power is drawn through power boards. The kitchen has had a few more outlets added.

I have fluoro lights everywhere that is not switched on and off constantly.

I have three 5 Watt CFLs on 24/7/365. Here, a Watt for a year costs about a dollar.

When I go on hols, I have designed and almost built a solar/LED/radio setup so that I can turn the mains off completely. Not for economy specifically, but for security against fire caused by faulty wiring in the roof. jack