My transformer is mounted just outside the power box in the basement.
Since all the heat in my finished basement where my office is located is
supplied by the ambient heat of the boiler and water heater, it adds to
the ambient heat. Right now, it is 28º F outside and it is 66º F inside
The fact that my doorbell transformer is not remotely warm to the
touch would indicate to me it is not dissipating 3 watts of power (and
it IS powering an incandescent lighted push button)
The lighted button helps find the key in the dark, so I don't really
care if it costs me $3 a year.
Such a door bell transformer is typically capable of a maximum of 7
watts or less when it is actually ringing the bell or door chime. Many
are not designed for continuous use. Next time I have spare moment
will measure the amount of electrcity such a transformer takes in it'
It's most likely a few milliamps. Well lets say 10 milliamps (A 100th
of one amp) to be generous to a fairly low grade transformer.
One 100th of an amp at 115 volts = 1.15 watts per hour, 27.6 watt
hours per day or 10,074 watt hours per year. That's just over 10
kilowatt hours per year. Although I doubt it is that high?
At my cost of electrcity (ten cents per kilowatt hour) that's just
about one dollar per year. A saving of one dollar per year (over 20
years) could probably amortize a capital saving at the start of that
period of around $12. Spend more that and it not economic.
Our transformer which has been in place for the last 38 years does run
slightly warm. In this cool climate that warmth does very, very
slightly, but insignificantly, contribute to the electric house
heating. Probably less so than normally leaving the bath and shower
water to cool down to house temperature.
Seemed like rather pointless exercise?
Actually, a big transformer that draws an amp with no load may use less
power than a little transformer that draws half an amp. It's resistance
from the copper windings and the iron core that uses power. Without
resistance, the current is 90 degrees out of phase with supplied
voltage, and that means no power.
I think the solution is a DC chime with a modern wall wart. To get the
Energy Star rating, a wall wart up to 50 watts can't use more than 0.3
watts idling. That would mean about 25 cents a year for electricity.
My remaining question is how long a particular wall wart would last.
On Wed, 19 Nov 2008 18:47:09 -0800 (PST), Seerialmom
One can be sure that light used about 2.75 watts of the three that the
user measured. Not that I'd trust a toy like the 'Kill-A-Watt' to make
accurate power measurements, especially at those lower power levels...
Congratulations. You've just made a potentially lethal accident waiting to
happen. And somehow I suspect your insurance won't pay if someone dies.
I would STRONGLY suggest you do one of 2 things.
1. Rewire that doorbell to it's original configuration.
2. Put a GFCI into the circuit
Either way I think would be safe. Option 1 of course would be cheaper, but
if you insist on saving the few pennies worth of electricity, then option
2 would work. And it would be a rather interesting experiment to see how
often the GFCI trips.
A gfci won't deal with the issue of low voltage wiring carrying 110. It is a
fire waiting to happen, especially if there is any possibility of rodents.
It is unfunckingbelievable what people will do to trim off a ten cent/year
That's right. Maybe ten cents in an entire year.
The cost of the pushbutton guarantees that the change will never ever pay
And that isn't counting the insane fire hazzard.
And what was your electric bill last month?
My electric bill is about $120 less each month because of things I have done
in the past to save energy. Basically many little things and a couple of big
things which all add up.
1 plus 2 plus 1 plus 8 plus 1 plus 1 = 14
This same idea works at the gas station. 10 cents less a gallon at a
particular station, fill up 15 gallon tank, do this 3 times a week... Can
make quite a difference if you know how to add.
This project was paid for by money I am saving on my electric bill. And it
was only about $8 because the transformer is in a closet by the door, so
short wire run. So $120 savings minus $8 leaves me with $112 *extra* money
Everything was installed and wired to code. Metal box and brass plate are
grounded, on GFCI circuit (wet location), wire is 14 gauge romex (regular
electrical wiring, not doorbell wiring), and the momentary push button
switch is rated at 120VAC (not a low voltage doorbell button).
This is my 401K. What better way to go into retirement than to set yourself
up for a low cost of living!
My electric rates went up 13 percent just this year. How much will they go
up in the next 20 years?
Basically there has been a trend to manufacture products which always use
electricity. I'm reversing that trend at my house. I turn this stuff off
when not in use (power strips with switches on them). And switches similar
Wow that $120 is half my average total monthly energy bill for this 4
bedroom all-electric house in a cold climate!
What do you use for heating? Gas (said to be cheaper) not available
here. And oil just too expensive and too much of a liability and
A neighbour (also all electric house, as most are here) has gone all
CFLs but says it makes very little difference to their electric bill.
CFLs make sense for outdoor locations so maybe when our long life
incandescent burns out (after several years) will try one outside.
Can't use CFLs in our two motion sensor fixtures, but those only come
on for short periods when activated.
You didn't trim $120/month by eliminating three cent/month transformers.
I also know that spending two hundred hours to trim three dollars a
year off one's electric bill is insanity.
Turn the thermostat two degrees and it'll outweigh removing every
single transformer in the house.
Your bell transformer was using $120 worth of electricity? That must
have been one hell of a big transformer, and an even bigger bell!
Try considering a cost/benefit analysis next time then do something
that is meaningful. Bottom line is that you saved perhaps a dollar or
two a year if you eliminated the door-bell transformer, not that
sillyi $120 you are quoting!
I had a friend some years ago who ran the communications
division of the local power company. This was back when
they had HF radios for communications and the techs actually
had to know something about electronics. They would get
electronic interference complaints which were often traced
to doorbell transformers. It was a very common problem and
one that many people don't even think of today.
Sorry, but I have a hard time believing that.
If it was "a very common problem", can you offer a cite proving that a
60 hz transformer and 10-50 feet of unshielded wire with 24 vac on it
can cause interference at radio frequencies?
Wouldn't you expect that if that story was true those big pole pig
transformers and all that higher voltage wiring running on the poles on
nearly every street would have caused the radios to melt? <G>
According to the FCC Interference Handbook, defective doorbell
transformers are often a source of interference to TVs and other
household electronics. It may be a neighbor's transformer. I think it
happens when part of the core comes loose and vibrates.
I'm no EE, but I would guess that most of the in-house interference is
back down along the power lines, not through the air. I know that on the
baby shortwave I use to AM-band DX myself to sleep at night, when some
unknown something in my house (or one of the neighbor's houses on the
same pole can) is running, I can't get S**t to come in. But if I unplug
the wall wart and run on batteries it comes in fine, as long as the
unplugged cord is over a foot from the radio. Intermittent as hell, and
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