http://www.diynot.com/forums/electrics/problem-with-dimmable-switch-halogen-lights.297058/
Just a bit of a coincidence,
Just a bit of a coincidence,
Which is live wire?
- Thread starter Frankie14
- Start date
Ah, I see. However, as you will understand, my comments related to what I'd been reading in this thread, not that other one which I hadn't even seen
Kind Regards, John.
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Paul_C
So it would seem, after reading through all of the above. The idea that it will make any difference whatsoever is laughable, and I can't understand why this seems to be provoking such debate. Which way round you connect the two wires to a 1-way light switch makes no more difference than which way round you connect two wires to a reversible 2-pin plug, i.e. none whatsoever.
Not necessarily. Depending on the wiring method being used for the 2-way you might want the supply live in the common or in L1 or L2. As it makes no difference which way round the 1-way is connected, it's sometimes a case of doing whatever is easiest to strap across the two switches depending upon the physical arrangements of the terminals (e.g. commons at the top and L1/L2 at the bottom versus one switch having the terminals inverted relative to the other).
Are they? Think about what happens when you connect L1 & L2 of one switch to L1 & L2 of another in the conventional 2-way arrangement: At one switch you have the live feed on the common and L1/L2 are live out, while at the other switch L1/L2 are live in and the common is live out to the light. Change to the alternate wiring method and which terminals are live feeds to the switch and which are live outputs depends entirely upon which way round the switches are set and changes as the switches are moved.
As John says, the terminals are really only marked because it's more convenient to use the same moldings for both 1-way and 2-way types. As far as any regular light switch used for plain 1-way switching is concerned, it simply makes no difference whatsoever which way round you connect it.
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Paul_C
In the traditional 2-way wiring which predominated at one time there was no common-to-common link between the switches - One common was the live feed and the other went to the light. The commons are only linked together with the alternate wiring method where the L1 & L2 terminals are also linked with live feed to L1 and light to L2 (or vice versa).
"Common" has nothing to do directly with how the circuit itself is wired; it refers only to the fact that the terminal so marked is the one which can be connected to either one of the other terminals depending upon the position of the switch. Something like a 10-way rotary switch also has a common terminal - The one which can be connected to any one of the ten other terminals depending upon the switch position. Whether there are ten separate feeds which can be connected to provide an output on the common terminal or whether there's a feed to the common which can provide an output on any one of the ten other terminals depends entirely upon the application at hand.
No they dont unless theres an intermediate switch
Rubish up until recently mk logic one way was totally different to a two way and a lot of makes still are.
Exactly - you just beat me to that analogy. I was 'brought up' on N-way rotary switches, and the 'rotor' terminal was always called "common" - and I presume that's how the term came to be used with 2-way light switches - i.e. a term relating to the construction/function of the switch, not anything to do with what circuitry was connected.
Also, I'm not even sure that the 'L' of 'L1' and 'L2' originated as having anything to do with live/line. I have some old rusty cast iron changeover switches (not in service
) in which the terminals are labelled 'Common', 'Load 1' and 'Load 2' - so I just wonder whether that might possibly have been how 'L1' and 'L2' originated?Kind Regards, John.
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Paul_C
Consider what happens to the commons of the two switches. The "in" and "out" functions are indeed swapped between the two possible switch position combinations which result in the light being on.
O.K., perhaps I should have qualified it as some switches. Some types do use the same basic moldings, as where there is an L2 marking but no terminal actually fitted in that position. As for the types which don't, I have no idea why the manufacturers think it necessary to put C and L1 labels on the two terminals, except perhaps for some peculiar desire to be somehow "consistent" with the C/L1/L2 on the 2-way versions.
Look at many old 1-way tumbler switches and there were absolutely no markings on the two terminals because there was no need for any.
Paul is essentially right, and it's irrelevant whether or not there is an intermediate switch .....
... which is/are the 'live feeds' to the right hand switch - 'C' or L1/L2 - and which is the 'live output'??
Kind Regards, John
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Paul_C
Precisely. I too was brought up on multi-way rotary switches and it seems such a simple concept that perhaps that's why I can't see why there seems to be so much misunderstanding about what "Common" on a simple 2-way light switch means.
Interesting, and the "Load 1" and "Load 2" markings clearly suggest what application was in the designer's mind, when the switch could just as easily be used to connect a single load to one of two different sources.Also, I'm not even sure that the 'L' of 'L1' and 'L2' originated as having anything to do with live/line. I have some old rusty cast iron changeover switches (not in service
Some older 2-way light switches had terminals marked "1 way" and "2 way," or "1W" and "2W," plus a common, making it clear which terminal needed to be used in a 1-way application to end up with the switch operating the normal way round of down for on. I have a few old round GEC types (A.C. only, not tumblers) from the 1950's/60's which are so marked.
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Paul_C
Then consider the bottom diagram here.
In the switch positions shown, common on the right-hand switch is "out" while common on the left-hand switch is "in." Flick both switches over so that the light is still on, and common on the left-hand switch becomes "out" while the common terminal on the right-hand switch becomes "in."
Paul is essentially right, and it's irrelevant whether or not there is an intermediate switch .....
... which is/are the 'live feeds' to the right hand switch - 'C' or L1/L2 - and which is the 'live output'??
Kind Regards, John
sorry john
Thats the conventional way
Try the alternate way drawing which paul c refers to
Either L1 or L2 will be live regardless of switching and the other terminal will always be the switch live
You seem to be 'wriggling'. Regardless of which method you regard as 'conventional' (today, rather than in the past), and regardless of anything that Paul said ... just answer my previous question, namely:sorry john Thats the conventional way
Either L1 or L2 will be live regardless of switching and the other terminal will always be the switch live
Kind Regards, John.
Better still, show me a drawing that relates to the alternate wiring method paulc refers to above
Thats a nice drawing of what paulc refers to as the conventional wiring as he has described, im not disputing that, L1, L2 output does alter with switch status.
If you agree and think paulc is right then ive underestimated you john
In the bottom diagram, please explain how if the intermediate was removed, L2 could possibly change from being live to a switchlive, regardless of the switch positions
Better still, show me a drawing that relates to the alternate wiring method paulc refers to above
Thats a nice drawing of what paulc refers to as the conventional wiring as he has described, im not disputing that, L1, L2 output does alter with switch status.
If you agree and think paulc is right then ive underestimated you john
Kind Regards, John.
Edit: Diagram tidied
You slipped this bit in whilst I was drawing/typing!
The answer is that, as you know, that cannot happen. However, the 'Com' terminal of the switch changes from being 'L in' to 'L out' - which is what I meant when I said that Paul was 'essentially right'. It certainly puts paid to the assertion that L feed goes to 'Com' and that 'Com' is never 'L out' (switched L).
Kind Regards, John.
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