The K M Links Game - December 2024 Week...
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Student Neighbour Practical Problem
21 Answers
Using 2 switches of the type 'single pole double throw',
sketch an electrical diagram to show how an upstairs light bulb
can be controlled from either the hall downstairs or from the upstairs landing.
sketch an electrical diagram to show how an upstairs light bulb
can be controlled from either the hall downstairs or from the upstairs landing.
Answers
You did state 'sketch'. https://
14:40 Fri 14th Apr 2023
Excellent work M'Lud.
There are many ways. Here's a simpler one...........
https:/
There are many ways. Here's a simpler one...........
https:/
Whilst the other two diagrams are perfectly correct (diagramatically) and would work, in practice a house would not be wired like that.
To take the example of a simple one light/one switch arrangement, see the diagrams in the link below. The upper diagram would work, but there is the problem of dealing with the neutral (black) wire running past the switch. I would suggest in practice a junction box would be used so as to provide a pair of wires to feed the light and a pair to provide switching via the switch. A similar principle applies to my two way switching arrangement.
https:/
I had a trickier problem when I devised my garden lighting a few years ago. I had two lights, one at each end of the garden, which I wanted to control simultaneously from either of two switches, one at each end. I could find no practical way of doing this other than to wire the lights in series and using 110v (building site) bulbs.
To take the example of a simple one light/one switch arrangement, see the diagrams in the link below. The upper diagram would work, but there is the problem of dealing with the neutral (black) wire running past the switch. I would suggest in practice a junction box would be used so as to provide a pair of wires to feed the light and a pair to provide switching via the switch. A similar principle applies to my two way switching arrangement.
https:/
I had a trickier problem when I devised my garden lighting a few years ago. I had two lights, one at each end of the garden, which I wanted to control simultaneously from either of two switches, one at each end. I could find no practical way of doing this other than to wire the lights in series and using 110v (building site) bulbs.
You're correct NJ. I wondered when someone would pick up on that.
The main two methods are known as ' Conventional 2 way switching' and The 'Conversion method'
We used to wire houses with the conventional way upto about the 90's.
With singles and earth and a 2 core and earth for the strapper.
But the conversion method is more used today with a 3 core and earth acting as a strapper cable.
Less chance of a borrowed neutral. (Against the regs BS7671)
But good on you for spotting it. :-)
The main two methods are known as ' Conventional 2 way switching' and The 'Conversion method'
We used to wire houses with the conventional way upto about the 90's.
With singles and earth and a 2 core and earth for the strapper.
But the conversion method is more used today with a 3 core and earth acting as a strapper cable.
Less chance of a borrowed neutral. (Against the regs BS7671)
But good on you for spotting it. :-)
NJ> 19.56
Student neighbour thanks you for your effort and hopes you'll contribute to further questions in the future!!
Unfortunately this time, your answer is not relevant to his needs. HIS reasons:
1. DC voltage unrealistic in a domestic home set up.
2. Switch 1 unrealistic, as your diagram shows 4/5 terminals where in practice there would be just 3 (L1, L2 and C)
3. Only need basic diagram to show the principle of connecting the 2 single pole double throw switches without having to trace wiring.
4. Old cable colour coding.
Now Me LOL
I would add, the Junction box is superfluous and would only add to the cost of installation. The link below shows a conventional installation in line with practices today on new builds. I admit this also requires a lot of tracing to ensure it is wired correctly!!
https:/
It is acknowledged that installing Up/Down stairs lighting, to overcome the Neutral wire termination issue, the design cannot get away from 3 core and earth cable between switches!!
Wishing everyone the very best of luck on the grand national :-)
Student neighbour thanks you for your effort and hopes you'll contribute to further questions in the future!!
Unfortunately this time, your answer is not relevant to his needs. HIS reasons:
1. DC voltage unrealistic in a domestic home set up.
2. Switch 1 unrealistic, as your diagram shows 4/5 terminals where in practice there would be just 3 (L1, L2 and C)
3. Only need basic diagram to show the principle of connecting the 2 single pole double throw switches without having to trace wiring.
4. Old cable colour coding.
Now Me LOL
I would add, the Junction box is superfluous and would only add to the cost of installation. The link below shows a conventional installation in line with practices today on new builds. I admit this also requires a lot of tracing to ensure it is wired correctly!!
https:/
It is acknowledged that installing Up/Down stairs lighting, to overcome the Neutral wire termination issue, the design cannot get away from 3 core and earth cable between switches!!
Wishing everyone the very best of luck on the grand national :-)
BA to Zebu for his sketch which looks like it was drawn with a rolling pin LOL But neighbour did point out you can see what is going on immediately without having to trace wiring. Also L1, L2, Com and Earth terminals are marked.
Zebu, polite notice, neighbour says not to put more information than is asked for!!
Zebu, polite notice, neighbour says not to put more information than is asked for!!
Before being condemned by the IEE or BS (whatever they call themselves these days) inspectorate for deliberate hardwire in SW1, the bulb can be turned on from either switch.
The inspectorate aside, no prizes for working out the inherent flaw with this circuit arrangement.
Perhaps a 3 position rocker switch could circumvent the problem?
Anyway, let us call it the poor man's Twin & Earth (TW+E) solution to upstairs and downstairs lighting control ;-)
https:/
The inspectorate aside, no prizes for working out the inherent flaw with this circuit arrangement.
Perhaps a 3 position rocker switch could circumvent the problem?
Anyway, let us call it the poor man's Twin & Earth (TW+E) solution to upstairs and downstairs lighting control ;-)
https:/
kuiperbelt, Your diagram is not conventional (it's the conversion method) used today to eliminate the possibilty of a borrowed neutral.
Wiring in singles and earth (was) the most cost effective way of wiring a lighting circuit. unfortunately those skills have got lost over the years as a lot of the young sparkies couldn't get their heads round it. (Sad but true) So the easy option was to use the more expensive(at the time) 3 core and earth (the conversion method)
Because more 3 core is in demand and singles have gone out of demand. the manufacturing costs have swung the other way.
It was simple to rectify the borrowed neutral back in the day by taking a single neutral and earth to the upstair(landing)light. thus keeping the upstairs and downstairs separate.
But as I say, the prefered method today is what was known as the conversion method when 3 core and earth came onto the scene at a price that was affordable.
Wiring in singles and earth (was) the most cost effective way of wiring a lighting circuit. unfortunately those skills have got lost over the years as a lot of the young sparkies couldn't get their heads round it. (Sad but true) So the easy option was to use the more expensive(at the time) 3 core and earth (the conversion method)
Because more 3 core is in demand and singles have gone out of demand. the manufacturing costs have swung the other way.
It was simple to rectify the borrowed neutral back in the day by taking a single neutral and earth to the upstair(landing)light. thus keeping the upstairs and downstairs separate.
But as I say, the prefered method today is what was known as the conversion method when 3 core and earth came onto the scene at a price that was affordable.
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