Measured and verified:
When my phone charger is plugged in and actually charging my phone, the Kill-A-Watt meter registers 4 watts.
When my phone charger is plugged in but not charging my phone, the Kill-A-Watt mater registers zero watts. It must be greater than zero, but probably less than half a watt.
The same is true for many other electronic devices in my home, including my computer monitor, plasma TV, and stereo receiver: when they’re plugged in but turned off, the Kill-A-Watt indicates zero watts.
My PC uses 1 watt when it’s fully turned off, but 3 watts when it’s in “sleep” mode.
Bottom line, most electronic devices these days (especially wall-wart chargers) are not “energy vampires” the way they used to be.
The surprise was our Tivo DVR, which is consuming 37 watts, 24/7. That’s about $3.75 a month. :eek:
For a while, I had a plan that could go up to $0.65/kW-h (peak hours on a few hot days). Even aside form that, the marginal price could easily be >$0.30/kW-h. My average rate was not that high (tiered prices, like taxes), but when cutting energy use, the savings is from the marginal rate, not the average. Back when LED light bulbs were $40, it was still worth the upgrade for me because the marginal rate was so high.
You could substitute AC household wiring to a doorbell switch. Before the transformer. Momentary button switch. Switch off, no power to transformer. But it better be a very safe switch. So as not to electrocute people ringing the bell. Unless you want to…
An interesting idea, but probably not cost-effective.
Since it’s operating at a full 120 volts, you would have to use electrical code approved cable for that. And the smallest (cheapest) that is in common use is NM 14-2 (‘Romex’) wiring – just like that to wire the lights in a house – that’s way more power than a doorbell uses, but it’s the smallest available legal wiring for 120V inside walls. Then you would need an approved electrical box at the door (instead of just a hole for a pushbutton), and it would probably have to be a waterproof one, as it’s exposed to the weather. Then you’d need a code-approved switch. A switch like a normal light switch, except spring-loaded, would work, but people are used to a push button, so you might want ne of them. And you’d need a bell or chime that works on 120V; most of them are 16V or 24V.
All this is available, but it’s generally quite a bit more expensive than the low-voltage materials used in doorbell circuits. The biggest expense is the electrical wire needed (and that’s what you’d need the most of). You could probably operate a doorbell transformer for decades, for the the added expense of a 120V doorbell system!
I’ve got a ‘battery free’ wireless doorbell - the bell push contains a piezo device that generates enough power for the signal to the base unit. The ringer base looks just like a plug in nightlight that goes straight into a socket anywhere in the house (so it can be moved around, but there were two of them in the pack so we just have one upstairs and one down.
The ringer consumes very little power and never feels warm to the touch