why is a 3way sw called a 3way not a 2way

[rick boyd]

why is a 3way switch called a 3way not a 2 way like untrained people call it,?

I use them all the time but can't answer my helpers question.



Rick

 

[charlie b]

It is not a matter of how many positions the switch can have (i.e., up or down is only two positions). It is a matter of how many ways current can get to the switch, how many paths current can take on its way to the switch. Think of driving down a road, and coming to an intersection at which you have to take either the left fork or the right fork. That is commonly called a ?3-way intersection.?

 

[SPDsk8er]

Excellent way to describe it, Charlie. I've been asked this question many times, but never had an answer as clear and easy as you put it!

 

[zog]

Great question, great answer!

 

[stickboy1375]

If i'm not mistaken, only America calls it a 3-way, every other country calls it a two way...

 

[hockeyoligist2]

Ist nicht drei ist zwie

 

[dbuckley]

So let me get this straight..... you have a corridor with a switch at each end, so two switches, and you call it three way switched...?

That is what the rest of the world calls a two way switched; a three way switch arrangement has, well, three or more switches...

 

[iwire]

It is a matter of how many ways current can get to the switch, how many paths current can take on its way to the switch. Think of driving down a road, and coming to an intersection at which you have to take either the left fork or the right fork. That is commonly called a “3-way intersection.”

I am not sure I agree. In the intersection I can literally choose to go three ways, left right and back.

In a three way switch only two paths are available.

 

[Dennis Alwon]

So let me get this straight..... you have a corridor with a switch at each end, so two switches, and you call it three way switched...?

That is what the rest of the world calls a two way switched; a three way switch arrangement has, well, three or more switches...

So let me get this straight if you have 4 or 5 switches it is called a 3 way? :grin:

Looks like both continents are wacked.

 

[infinity]

I remember reading somewhere that the British term three way switch came from the concept of a three wire switch.

 

[t bone]

3 way switch

3 way switch

They call it a 3 way because of the three terminals on the switch. You should try trade school!

 

[t bone]

Waste of time go to trade school. Three terminals on the switch thats why it is a three way

 

[dbuckley]

So let me get this straight if you have 4 or 5 switches it is called a 3 way? :grin:

Not quite; for example a corridor with five switches operating the same lights would have what an EC would call a two way switch at each end, and three three way switches in the middle

But yeah, its normally just two way or three way, more is uncommon...

 

[480sparky]

I was told way back when it's becuase 3-ways are basically SPDT switches. And old SPDT switches had three positions, On, Off, and On.

But today, my answer would be, "So you can tell the difference between the amatuers and the pros."

 

[George Stolz]

They call it a 3 way because of the three terminals on the switch. You should try trade school!

If they taught manners in trade school, your first posts to this forum would not have been so rude. I invite you to cheer up, negativity benefits noone here.

 

[480sparky]

They call it a 3 way because of the three terminals on the switch. You should try trade school!

So a DPST switch should be called a 4-way? :-?

 

[220/221]

They call it a 3 way because of the three terminals on the switch. You should try trade school!

And a single pole sw would be a two way.


THINK before you post






I asked the same question in 1973 and never got a good answer.

I also asked why single phase wasn't two phase. I got a reasonable answer for that.....I think.

 

[ItsHot]

Yogi

Yogi

Why does Yogi bear wear a hat and tie, but no pants?

 

[charlie b]

I am not sure I agree. In the intersection I can literally choose to go three ways, left right and back.

You came to the intersection along one path, and you will leave along one path. The car behind you might leave along the other path. There are a total of three roads on which a car may be travelling. But to make the analogy complete, we must consider that one of the two paths leading away from the intersection might be closed today, and the other might be closed tomorrow.

In a three way switch only two paths are available.

No, the switch offers three paths along with current might be flowing. Current comes in on one, and out on one of two others. That is a total of three.

 

[roger3829]

3-way three screws.

4-way four screws.

that's how it was explained to me in 1976