Which direction is "correct" for a single-throw switch?

[chalsall]

Originally Posted by only_human

The only SPST switches that I'd prefer to see using down-for -on are main power circuit knife switches, pedal switches and occasionally other momentary switches.

Really? Down for on?

I once entered the electrical room during an emergency with my second behind me.

I kept pulling down the circuit breakers (many pops etc) -- eventually I figured out the bad circuit (my second had already run away).

[only_human]

Originally Posted by chalsall

Really? Down for on?

I once entered the electrical room during an emergency with my second behind me.

I kept pulling down the circuit breakers (many pops etc) -- eventually I figured out the bad circuit (my second had already run away).

I'm talking of those primitive big metal blades that are pulled down to close a circuit; I did say knife switches.

[chalsall]

Originally Posted by only_human

I'm talking of those primitive big metal blades that are pulled down to close a circuit; I did say knife switches.

Generally, such blade switches are pulled up to close a circuit.

But please forgive me, I'm from India. What do I know....

[MattcAnderson]

Hi All,

I think a single switch should have up for on. This is more intuitive.

I have included the wiring diagram for a two switch scenario.

Regards,
Matt

[only_human]

Originally Posted by chalsall

Generally, such blade switches are pulled up to close a circuit.

But please forgive me, I'm from India. What do I know....

You likely know more than me; no doubt you are right. The only reason I said down was mentally it seemed less likely that one would be reaching across the switch while the exposed metal was voltage live. I didn't check the real world and didn't mean to imply that I gave it much thought. I was just venturing an opinion and not a particularly valuable one.

in fact I waz wrong on this. If down is on, an unsecured switch could fall into on.

[kladner]

Originally Posted by R.D. Silverman

Consider a light in a stairwell controlled by two separate switches......

The light is off, both switches are "down". The switch at the bottom is thrown and the light
turns on. One ascends. One now throws the switch at the top and the light turns off....

That is called a 3 way circuit. It has two DPST (oops) SPDT switches. Why it is called 3-way is beyond me. Perhaps it is because 3 wires are involved instead of 2. However, it is not the basic single pole single throw switch. To tell the truth, such setups kind of bother me because the switch position is not informative.

I actually have two standards: OFF is either down or left.

[science_man_88]

Originally Posted by kladner

That is called a 3 way circuit. It has two DPST (oops) SPDT switches. Why it is called 3-way is beyond me. Perhaps it is because 3 wires are involved instead of 2. However, it is not the basic single pole single throw switch. To tell the truth, such setups kind of bother me because the switch position is not informative.

I actually have two standards: OFF is either down or left.

one thought that came to me is maybe because from any one starting position as off/on there's 3 other ways to combine the two ( some times in sink) that the light can be turned to the other setting.

[Batalov]

Edward Tufte would have probably suggested that because the semantic of the on/off switches is broken for the "corridor flips", they should have been replaced with e.g. push-buttons.

I have these in three places in my house (e.g. switch on, go upstairs and switch it off) and I don't like the "up-down" switches for them. (making a mental note to replace)

[aurashift]

Originally Posted by chalsall

Mr. Silverman...

Please reread the opening post.

Specifically "To be clear, this is only relevant for single pole switches; three and four way switches can't be configured to have a "correct direction" for on because there's more than one switch in the equation.

Doesn't that kind of invalidate the question though? The correct way is to flip the switch to your desired result.

[retina]

Why must it be up-vs-down. Throw those switches side-to-side and then there would be less argument.

Originally Posted by Brian-E

In our flat the two configurations are about evenly represented amongst all the switches. It's a mild annoyance when I'm feeling particularly prickly.

If you have a screwdriver then a few minutes work could ease your frustrations.

[LaurV]

Up=ON is the "correct" way, for many reasons.

Think about ELCBs (electronic circuit breakers) for example, some have springs, some work on gravity. When I was working at the university we had circuit "holds" for all the labs, they were working on "gravity" too. They looked like a normal light switch, but there was a small electromagnet inside, which was "holding" the switch in ON position. The lab assistant would switch the electricity ON before the lab starts, and switch it OFF at the end. All equipment was powered from the power rails passing through those switches. You put the switch ON by lifting a small knob up, then it is held "up" by the current passing through it. If there was an electricity break, the switch went down (because no current to hold it), and OFF. And it didn't went back ON by itself if the power went back ON in a flash. The reason is that most electronic stuff (not only in those labs, and computers included) are sensitive to negative power spikes, you may know that when you turn your computer OFF, you should NEVER turn it immediately ON. Wait 5-10 seconds before turning it ON again. An OFF-then-immediate-ON shock can (and it will!) damage your power supply.

Also, think about rows of automatic fuses, you turn them ON by pressing them "up". When one "falls", then it "falls", it means "down", you can see the lever down, or the red mark which means "down".

Since I am in Thai I have an eternal problem with switches. They are all viceversa, everywhere, including in my house. You have to press the switch down to put the light on. This is somehow stupid. In my house, every time a switch failed (they die from time to time, you can imagine I lived in this house for 15 years, some things get broken and you have to fix them, from time to time), so, every time a switch or power plug died, and I had to repair them, I mounted them in the "correct" position. This makes the things even more difficult, because now we have a mix there and I am too lazy to take that screwdriver and change all.