In several countries, electrical outlets have physical on/off switches used to control the energy flow sent to the connected appliance. If the switch is set to the on position but nothing is connected to the socket, will any energy be used/wasted?
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3\$\begingroup\$ Compare it with this: If a tap is closed, is water still send to it? \$\endgroup\$– OldfartFeb 2, 2020 at 15:42
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\$\begingroup\$ But will electricity leak out if the switch is on, same as when a tap is left open? @Oldfart :) :) \$\endgroup\$– Solar MikeFeb 2, 2020 at 15:47
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\$\begingroup\$ I don't know, I have never put a cup underneath a socket to see what leaks out. \$\endgroup\$– OldfartFeb 2, 2020 at 15:54
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\$\begingroup\$ if something was actually leaking from the outlet, then how would turning off the switch stop the leak? ... the leak would move to the switch \$\endgroup\$– jsotolaFeb 2, 2020 at 16:54
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4 Answers
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A switched outlet with nothing plugged into the outlet will generally not consume any power when the switch is turned on. There are a few cases where this may not be totally true. Some outlets may have an indicator to show that the outlet has a live power connection and the indicator circuit will consume a small amount of power.
Some indicators would be a neon bulb, others LED and some may be small incandescent bulbs. Each type will consume a small but different amount of power.
answered Feb 2, 2020 at 15:39
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2\$\begingroup\$ Also nowadays some outlets have built-in USB power supplies, which will use a small amount of power. \$\endgroup\$ Feb 2, 2020 at 17:00
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If the switch is set to the on position but nothing is connected to the socket, will any energy be used/wasted?
simulate this circuit – Schematic created using CircuitLab
- For electrical energy to be consumed current must flow.
- Air is a very good insulator. We use air as an insulator on the high-voltage lines you see criss-crossing the country.
- When we open a switch a millimeter or so the gap is sufficient to prevent current flow.
- The gap between the contacts of your socket is much more than a millimeter. No current will flow from one contact to the other. No energy can be consumed.
If the switch is set to the on position but nothing is connected to the socket, no energy be used/wasted.
answered Feb 2, 2020 at 15:57
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Power outlets which are switched on with nothing connected will use no power.
However, if devices are turned off but still on standby and still connected to the on power outlet then they do still waste/use a little electricity such as TV’s , phone chargers etc.
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\$\begingroup\$ @SolarMike to clarify, in order not to consume any energy, the switch must be totally mechanical one (the one that makes loud "click" sound and physically disconnects wires). Anything relying on electronics (like anything with indicator lights, soft switches, capacitive touch sensors, push buttons instead of switches) will still consume some power. even when off. Yes, that means that your PC will always consume some energy even when off and even if it's mechanical on/off pushbutton looks like mechanical switch - unless you reach on back and use disconnect switch on ATX PS near the cable. \$\endgroup\$ Feb 2, 2020 at 17:51
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1\$\begingroup\$ @MatijaNalis Dan did the job by editing that answer... \$\endgroup\$ Feb 2, 2020 at 17:59
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From the title:
is energy sent to the socket when nothing is connected to it but the switch is on?
Yes it is, in preparation for something to be plugged in and use that energy.
From the body of the question:
If the switch is set to the on position but nothing is connected to the socket, will any energy be used/wasted?
Energy cannot be used by the socket because nothing is plugged in but, energy is slightly wasted in the transportation of voltage to the socket by the cable. It’s very small but nonetheless energy is burned. The cable has capacitance and series resistance and a small reactive current flows that passes through the copper resistance.
If the cable is very long then more energy is wasted in transporting voltage to the socket.
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1\$\begingroup\$ Energy is not sent to the socket when nothing is connected. Voltage is, sure, but no energy goes anywhere. This might seem pedantic, but the difference is crucial to the OP understanding the basic principle of what they're asking about. \$\endgroup\$– GrahamFeb 3, 2020 at 0:40
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\$\begingroup\$ @Graham - 'energy sent' is not a thing, +1. A live wire with no current flow simply has potential. If there's current being drawn then the answer is yes, and vice versa. \$\endgroup\$– MazuraFeb 3, 2020 at 1:40