It took me a while to figure out how to wire a 2 way switch, and also a
single switch and light...
I had to do some dummy drawings so that I never forgot...!!!
I see a lot of people asking how to wire a 2 way light, so I decided to put
my dummy drawing on the internet in case anyone wants to have a look..!!!
Please also feel free to criticise or ask me to change if you so feel the
I have put it here...
is NOT the way to wire 2-way switching in twin & earth cable.
The correct way to do it is to wire a 'switch drop' to one of the switches,
exactly as for a single switch, and then run a 3-core & earth cable to the
second switch. Intermediate switch(es) - unlimited in number - can be
included along the way, if you like. The wiring between the switches looks
0===========0 0===========0============= 'Live'
| \ / |
C 0================================O C
\ / \ /
0===========0 0===========0============= Switch return
L2 Optional L2 (switched 'live')
[Diagram credit: Dave Plowman, posted here 09/01/2003]
Your way creates a large current loop enclosed by the rose and switches
which can cause interference to inductive loop systems - and if dimmers
and/or discharge lighting are involved, it will cause RF interference, e.g.
broadcast radio interference in the 'AM bands'.
You should also add to your diagrams the need to sleeve, in red, the ends of
any black wires used for switched 'live'.
3-core and earth cable can also to used to carry a switched 'live' as well
as the L & N when looping-in the supply between two roses whose lights are
controlled by the same switch(es) - in this case use the yellow wire
(sleeved in red) for the switched live and the blue wire (sleeved in black)
for the neutral.
Get yourself a copy of the Which? Book of Lighting and Wiring!
It'll work fine, however you do NOT use the earth wire for twin and
earth as a live feed! Your light points presumably have no earth wire
running to them now - and that would not meet the 16th edition wiring
Plus if you had a metal light fitting and you haven't got it earthed
you are running the danger of someone getting fried when they change
I am still misunderstanding what is wrong ..!!!!
You say that I should not use Earth as Live, but in my drawing, it does not
You are concerned that the light fitting is not earthed, but in fact it
Yellow wires are earth..
I was recently on a site being worked by Spanish electricians. The
continental 3-phase colours are black and 2 browns for phase and blue
They thought I was mad when I told them that in the UK we use red, blue
and yellow so the distinct phases could be identified. :)
A. Top posters.
Q. What's the most annoying thing on Usenet?
Your way is very non-standard and should not be posted as an example to
For example the 3 core and earth that is normally used to wire two-way
circuits has a YELLOW wire in it. Someone could confuse that with the yellow
wires in yours circuits which are in fact earth.
Hence, someone could end up with a dangerous circuit and maybe you will be
my only comment is that the way you have wired the Two Way switching
circuit is not the 'normal' way to do it.
The standard way to do them is to wire one switch to the ceiling rose.
and then interconnect that to the other switch with 3 core and earth.
Sorry Gertzy, but the drawing are very confusing and very dangerous if
followed by someone who doesn't know any better.
Have a look here to see how it should be done:
The only main thing I see wrong with your drawings, is the fact that you've
made the earth conductor the colour of a common live phase. Earth should
always be marked in green or green/yellow and no other colours. That's why
I said your drawings would be confusing to others trying to follow the three
core cable version of the wiring configuration.
Three core and earth cable commonly has the colours RED, BLUE and YELLOW as
its live phase carriers, and has the common bare copper conductor as the
earth bonding. Your drawing shows the yellow conductor connected to earth
on the appliances, so then, anyone following your drawing may connect the
yellow to the casing of the switches and lamp holder and electrocute
Talking of lighting circuits ...I started replacing a lot of ceiling roses last
month and was shocked at the dreadful state of the wiring. Bare wires/ burnt
wires, numerous melted connectors. Most of the excess heat melting I assume was
caused by the system being overloaded with too many 100W bulbs instead of 60W
jobbies.Could easily have been statistics.
Is there a simple way of figuring out the maximum wattage on a lighting circuit
(size of the MCB?). Our downstairs circuit has 9 ceiling fixtures plus an
outside light (plus maybe security light).
All the roses I've replaced have the maximum wattage clearly listed but the
original ones don't and while we have now replaced most 100W bulbs with low
energy bulbs it would be nice to know what the max should have been.
It makes you realise when you hear on the news "caused by an electrical fault"
that not all house fires are ciggies down the sofa or chip pans.
On 12 Oct 2003 21:03:07 GMT, firstname.lastname@example.org (Wdyw) wrote:
Just a guess but you could probably do this with a clamp meter on the
live feed to the lighting circuit. Switch all the lights on to see
what the load is then multiply by 240 to get the wattage.
I bought a clamp meter on ebay for about 15 quid several days ago. It
might not be particularly high quality but it's purpose for me was to
give general indications rather than accurate readings.
Alternatively, if you aren't into techy solutions, wander round and
add up the wattages for each of the light bulbs. That has the
advantages that (a) you don't need a clamp meter and (b) you save
electricity by not having to turn the lights on.
... but the overheating and so on is almost certainly caused by using
100 watt bulbs in sockets designed for a maximum of 60 watts and not
to do with the circuit being overloaded. Overloading of the circuit
as a whole would likely only affect the fitting nearest to the CU
and/or the wiring between it and the CU.
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