Electricity usage of an open light socket

[ryyeung]

In one of my bathrooms, I have 3 light outlets/mounts/or whatever they are called - 2 is mounted overhead the sink, and 1 is actually in the storage closet. One light switch operates all three lights.

Now, so when I use the toilet or whatever, I really only need the 2 overhead lights, while the 3rd one in the storage closet is NEVER-to-RARELY used. That closet contains Xmas and Halloween decorations that are taken out once a year.

To save electricity, I've removed the bulb from that 3rd outlet in hope of saving electricity. Does anyone know if that really work, or since there is electricity flowing to the outlet, then it really doesn't matter???

Also, what about safety leaving an open outlet while the other 2 bulbs are installed?

Thanks

[jason9945]

If there is no bulb then its not using any electricity.
If you have an open socket somewhere that a metal object fall into then its dangerous, otherwise its fine.

[cmackie]

If the bulb is in but the switch is off, there won't be any power used either since the swith completes the circuit. No power savings by removing the bulb.

[ryyeung]

If the bulb is in but the switch is off, there won't be any power used either since the swith completes the circuit. No power savings by removing the bulb.

I need to click the switch and turn on the light for the overhead lights, which is also on the same circuit as the storage light - the light DOESN"T currently have a bulb on it. So from the reply, I guess I DO SAVE electricity if I leave the outlet empty even though the circuit is complete or "on".

[l69norm]

....Also, what about safety leaving an open outlet while the other 2 bulbs are installed?..

Just unscrew the bulb in the closet a bit so it doesn't light up. That way, there will not be any exposed contacts and you have the option of screwing the bulb back tight if you want light.

[Techhead]

Another suggestion would be to swap out the fixture for one with a pull cord.

http://www.hardwarestore.com/media/product/234534_front500.jpg

Keep it so that it is powered off by the cord, this way when needed you have a light at your finger tips (litterally) :idea: :D

[smithinparis]

To answer the post directly, leaving a wire connected to the power main will draw some current, even if there isn't anything connected to it. But the current really is insignificant.
I once had to calculate what the current draw of a 2m long lamp cord was, with the lamp off. Due to the capacitance between the lines, a 2 m long lamp cord would cause 1.8 uA to be drawn, even with the lamp off.
The amount of current drawn the the setup in question would be different (different length, different cable/insulation, ...) but the amount would be in the same order of magnitude.

Say the socket is roughtly 2 meters away from the light switch, the amount of power being lost by just having that cable connected, with no light on the other end would be 0.2 mW, which is 5x less power than the rated power consumption stated on the back of the pocket calculator that I just used to figure that out.

In terms of money, at $0.05 per kilowatt hour, you are looking at $0.0000072 per month.

[telman]

I was always taught that an electrical circuit needed to be a closed path in order for the electrons to flow.I have been questioning people who tell say unplug your toaster etc, to save electricity. So I really don't see how a empty lamp socket can draw electricity.

[smithinparis]

I was always taught that an electrical circuit needed to be a closed path in order for the electrons to flow.I have been questioning people who tell say unplug your toaster etc, to save electricity. So I really don't see how a empty lamp socket can draw electricity.

That's absolutely right, you do need a closed path to complete the circuit, and draw current ... but a closed path doesn't HAVE to be a metal contact. Consider two examples:
1) Your standard power supply that plugs into a wall uses a transformer which conducts electricity - not by the transfer of electrons - rather by a magnetic field. In this case there is no metal contact and no 'closed' circuit in the strictest (metal contact) sense. BTW, some fancy electric toothbrushes use this same principle to charge the internal battery without needing electrical contacts that can corrode in a bathroom environment
2) I'm stuggling to think of a common example of a capacitively coupled device that people might be familiar with, and I'm sure somebody more clever than myself will be able to step in. A capacitor is basically a device that contains two conductors (metal wires or metal plates), that do not contact. When an alternating current is (wall current for example) is placed on it, power will flow across, even though there is no contact. This principle is used in electronic filtering to let alternating currents flow, but not DC currents (eg battery power), or in stereo amplifier design to let the music through, but again not any DC.
For the subject of the post, the power cable contains two long wires that are side by side, that form a capacitor (not a very good one mind you), and because of that, the alternating electric field between the two will cause power to essentially leak between the two.
As for the toaster, I've often questioned the rational for unplugging it (like my mother always told me). Due purely to leakage, the amount of power lost is really insignificant. However, if you look back at the original toaster designs, that looked like a waffle iron on it's side, they were very dangerous because they were basically always 'live' with no switch to shut it off. I've always assumed that the idea behind the unplugging the toaster actually stems from the terrible designs of the original toasters, and advice simply being past down from generation to generation without any second thought.

[telman]

Thx, it hurt my brain but I get your train of thought!:idea:

[brunes]

2) I'm stuggling to think of a common example of a capacitively coupled device that people might be familiar with, and I'm sure somebody more clever than myself will be able to step in. A capacitor is basically a device that contains two conductors (metal wires or metal plates), that do not contact. When an alternating current is (wall current for example) is placed on it, power will flow across, even though there is no contact. This principle is used in electronic filtering to let alternating currents flow, but not DC currents (eg battery power), or in stereo amplifier design to let the music through, but again not any DC.

My toothbrush is charged via capacity couping. There are no contacts on the bottom of the toothbrush, it is a totally sealed system. The base has a coil inside it and the brush has a coil inside it, and when it sits on the base the toothbrush chargers via the capacitance *THROUGH* the plastic. Very slick system, as toothbrushes are exposed to a lot of water so this way there are no contacts to rust out.

[l69norm]

...For the subject of the post, the power cable contains two long wires that are side by side, that form a capacitor (not a very good one mind you), and because of that, the alternating electric field between the two will cause power to essentially leak between the two.....

It's the same reason why high voltage transmission lines aren't buried underground. The capacitance is so high that most of the energy in the power line is lost in as little as 30 miles vs. 300 miles for a power line installed on towers.

[dark169]

My toothbrush is charged via capacity couping. There are no contacts on the bottom of the toothbrush, it is a totally sealed system. The base has a coil inside it and the brush has a coil inside it, and when it sits on the base the toothbrush chargers via the capacitance *THROUGH* the plastic. Very slick system, as toothbrushes are exposed to a lot of water so this way there are no contacts to rust out.

Thats inductance, not capacitance. More akin to transformers then capacitors.

[dark169]

It's the same reason why high voltage transmission lines aren't buried underground. The capacitance is so high that most of the energy in the power line is lost in as little as 30 miles vs. 300 miles for a power line installed on towers.

high voltage lines are not burried due to a dozen other reasons. I would need to read up a little more but air forms better capacitors then earth. It has more to do with cost of 3 trenches, maintainability and reliability

[l69norm]

high voltage lines are not burried due to a dozen other reasons. I would need to read up a little more but air forms better capacitors then earth. It has more to do with cost of 3 trenches, maintainability and reliability

Yes, it's expensive. Long underground lines are usually converted from HVAC to HVDC. See:

http://www.aep.com/about/i765project/docs/UGvsOVHDPaper.pdf

IMPORTANT FACTORS AFFECTING UNDERGROUND PLACEMENT OF TRANSMISSION FACILITIES
AEP’s Operating Companies are occasionally asked to place sections of their transmission lines underground.... This paper outlines the various factors that govern decisions about the placement of transmission lines and whether they are built overhead or underground....

....Due to the different electrical characteristics of underground construction, the actual amount of power a buried line can carry is significantly lower than the amount of power an overhead line can deliver. Underground lines physically store a significant amount of electrical charge, which means that a larger portion of the line is required to carry the power flow. As a result, underground transmission lines must be relatively short or use expensive methods, like shunt compensation, to improve the flow of power.........

[nogoro]

any hazards with the moisture in the bathroom affecting the open socket? or maybe decreased lifespan of the light fixture?

[Bobui]

I think there are too many pot lights operated by one switch in my hallway and want to take out two. Is it better to:

1) Take the light bulbs out of their sockets and leave them bare
2) Turn the light bulbs halfway so it doesn't light up
3) Leave in a burned out light bulb

Thanks for your help!

[brunes]

I think there are too many pot lights operated by one switch in my hallway and want to take out two. Is it better to:

1) Take the light bulbs out of their sockets and leave them bare
2) Turn the light bulbs halfway so it doesn't light up
3) Leave in a burned out light bulb

Thanks for your help!

All three of these will break the circuit so it makes no difference, other than appearance.

For asthetic reasons, if you don't want to go to the trouble of actually removing the lights and repairing the ceiling, leaving the bulbs in halfway twisted IMO would look the best. Just make sure they are untwisted enought hat there is no chance they will accidentally make contact due to vibrations, as this could burn out the bulb quickly.

[Cough]

These fluorescent tubes are NOT connected to the power lines above


http://blog.makezine.com/richard-box.jpg

http://www.stockport.gov.uk/images/main/804367