Open/switch on the air-conditioner when we are home.

Which is correct? Open or Switch on?

  • 4
    Open is for containers, doors, or meetings. Turn on and Switch on are for all machines. May 8, 2014 at 0:18
  • 1
    I believe there are some languages whose cultures came late to the electricity scene where opening and switching on are synonymous. Likewise closing and switching off. May 8, 2014 at 1:11
  • @BlessedGeek Similarly, even in English some snuff, douse, and otherwise extinguish electric lights (even though no one would ever ignite, kindle or inflame them).
    – choster
    May 8, 2014 at 13:53
  • Even though the question is closed, I just had a thought. I do say 'Open the air-con' and I think it's because it's common to say open the air-con a bit more meaning make it colder, or close the air-con a little meaning make it a bit less cold. turn up the air or turn down the air are confusing because turning it up, means set the temperature lower and vice-versa.
    – Frank
    May 15, 2014 at 6:04

3 Answers 3


The preferred way to say it is "turn on":

Turn on the air-conditioner when we are home.

See definition #1 at http://www.merriam-webster.com/dictionary/turn%20on -

to activate or cause to flow, operate, or function by or as if by turning a control


Electrical circuits are active only when the path of electricity is completely from source to load and back to source e.g. battery to fan and back to battery. By convention, a circuit in which electricity can follow this path is "closed" and one in which it can't is "open." Usually, closing and opening a circuit is done by a switch but a short can open a circuit as well.

"Close the switch/circuit" is a command to activate a circuit, usually by analogy with the old knife style up and down switches. So, you really can't start something electric by "opening" anything.

Most phrases for activating a circuit appear to arise from the mechanical motion of switch used to close the circuit. "Turn on" is from a rotary switch which itself probably originated with ball valves on gas appliances that let gas flow depending on on the whether the valve handle is turned parallel in line with the flow or perpendicular to it. There are also flip switches so you can "flip on" a circuit. I suppose with the new touch interfaces, some kid will get told to go "stroke the AC."

If you have someone saying "open" an electrical device, they are probably preserving an archaic analogy to some gas operated device e.g. you could "open" the valve on a gas heater to start it.

In the case of an air conditioner, it's probably a transference from "open a window."


I'd never really thought about this but now I have I would...

Turn on the TV

Switch on the kettle

Open the air-con

Start the car

All done by flicking a switch or pressing a button.

  • Interesting Frank because despite the internet, ease of travel, the use of terms are still subject to both age and country of origin. I turn on the TV; who uses a kettle? But I think I would 'put it on', switch on the 'AC', and start the car.
    – Third News
    May 8, 2014 at 12:35
  • @Thirdnews What do you boil water in to make tea? I'm an ex-Englander and every house has (or had) a kettle.
    – Frank
    May 8, 2014 at 12:46
  • 1
    A microwave but when I have guests from Europe, I find the metal kettle, and leave it on the stove for their incessant use! ;-)
    – Third News
    May 8, 2014 at 13:17

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