Why are lights & GPO's on different circuits?

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Kid's school science question as per subject line.

Anyone got any answers - google's not co-operating and other than spreading
the load when we used to have 3ph into houses or to separate ELCB loads
which is a much more recent thing.

Ideas?




Re: Why are lights & GPO's on different circuits?

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Err, 2c, lights are generally in the ceiling, whilst GPOs are generally
supplied from under the floor boards. Also, lights usually draw less
current,socan have a lowervalue fuseand thus safer in the event of a short.

Re: Why are lights & GPO's on different circuits?

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Yes - physical location is valid - suspect teacher is looking for a more
technical reason. Fuse rating could be the answer however that would be far
in advance of what they have covered (yr 8).
thanks



Re: Why are lights & GPO's on different circuits?

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Go with fuse rating.
I don't see it as beyound Yr8. Really it is just applied resistor and they
usually cover resistance as one of the early parts of electrical circuits.

OTOH, I'm only guessing based on life experience.


Re: Why are lights & GPO's on different circuits?

"Den"
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** The problem is that teacher likely  THINKS  he or she knows the right
answer -  when they do not.




.....   Phil






Re: Why are lights & GPO's on different circuits?

"McKavity"

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** The reasons are partly historical, partly practical and partly human
safety.

1. When homes were first supplied with mains electricity, circa 100 years
ago,  the  ONLY  purpose was lighting  -   as appliances came along (
radios, vacuum cleaners, room heaters etc)  they were plugged into the light
sockets.

2. Appliances typically draw far more power than lighting does, so will
easily exceed the capacity of the cables fitted in the ceiling for
ighting  -  means a separate ( higher capacity) power circuit for appliances
is needed, preferably fitted at floor level.

3. If the ( now independent) power circuit is over-loaded and causes the
fuse to blow, it does not plunge the house into darkness - which would be
very unsafe for the people inside at night.

Then there is the issue of safety grounding, essential for appliances but
not required for ordinary lighting fixtures. So power circuits have three
pin sockets and 3 wire conductors, unlike typical lighting.


BTW:

Is your Christian name  " Phil " by any chance .................

Are you a dentist ?



.....  Phil





Re: Why are lights & GPO's on different circuits?

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Cheers Phil - all good reasons. Terry also suggested circuit fuse rating
differences. Overloading & lights out is another. Mmmm, I must have "over
thought" the question and was looking for something more fundamental.
\



Re: Why are lights & GPO's on different circuits?
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The wiring rules have required that all metal luminares be earthed
(except for double insulated and ELV ones), and in any case an earth
wire must be provided at the lighting point. This has been the law now
for over 20 years. Lighting circuits now also require RCD protection (as
do all circuits supplying socket outlets).

The main reason for separate lights and power is cost. Under the wiring
rules the minimum size conductor allowed for lighting circuits is
1.0mm^2, while for socket outlets (power points etc), the minimum
conductor allowed is 2.5mm^2, which costs more. In a typical
installation, you would use more cable for lighting than socket outlets,
as you have to run cables down the walls to switches, and you have two
way switches etc, further increasing the cable runs. All the conductors
  on one circuit has to be rated to carry the current of the protective
device.

Note: Lights can be on the same circuit as socket outlets. This is a
called a mixed circuit. Only requirement is that the conductors to the
lighting points has to be the same size an current rating as the rest of
the circuit, to enable protection by the circuit breaker (or fuse).


David

Re: Why are lights & GPO's on different circuits?
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At least get your childish insults correct Phil, that wasn't my post.

Dave.

Re: Why are lights & GPO's on different circuits?

"David L. Jones"
 "Phil Allison"
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**  Too many Daves in this tread.




.....   Phil





Re: Why are lights & GPO's on different circuits?
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  How about you pull your head in and be quite philthy befoer you get a
solution you wont like ?

Re: Why are lights & GPO's on different circuits?

"The Real Andy"
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*  Which proves MY point EXACTLY  !!

Because the wiring rule changes are  NOT  retrospective they  CANNOT
have anything to do with wiring practices that PRE - DATE  their
introduction.

YOU  IMBECILES  !!



...   Phil



Re: Why are lights & GPO's on different circuits?
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True, the wiring rules are not retrospective, but if you do *any*
alterations or additions to an old installation, then the new wiring
rules do apply to the part of the installation to which you have done
the alterations or additions.

If you add a new power point, or indeed technically change a single
power point to a double, on an existing circuit, then under the current
wiring rules, that final circuit has to be be protected by an RCD.
Similarly if you add a new lighting point to an existing light circuit,
you have to protect the circuit with an RCD. Note the 2007 wiring rules
require that the *circuit* be protected by and RCD, rather than the
*outlets*, which is a change from the old rules.

David



Re: Why are lights & GPO's on different circuits?

"David"
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**  So have nothing to do with this thread.

     You   PEDANTIC   LUNATIC  !!!



......   Phil







Re: Why are lights & GPO's on different circuits?
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They have plenty to do with this thread, and your incorrect answers and
comments to the OP's question in this thread. To quote your exact response:

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Safety grounding *IS* required for ordinary lighting fixtures, and is
certainly not a reason why lights and GPO's are on different circuits.

Please do us all favour, and actually go and *READ* the standards before
you go off half cocked, giving what you imagine might be an answer. When
I see your name in the Dept of Fair Trading list of licensed electrical
contractors, then I might possibly have a little respect for your answers.

David



Re: Why are lights & GPO's on different circuits?

"David the Utter Fuckwit "
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** Only in your demented, pig ignorant fantasy world.



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** But was not the case back even 20 years ago, let alone more than 50 years
ago.

Even now, the VAST MAJORITY of residences do not have it.

So it is a  MAJOR  reason why the  MAJORITY  of lighting circuits are and
have been for decades kept seperate.

No go eat a big packet of  Ratsak   -

you rediculous,  bloody TROLLING   PEDANT  !!



.....   Phil




.....   Phil





Re: Why are lights & GPO's on different circuits?
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  in reality you got the wrong answer again , any alteration to the
circuit requires compliance , even a dick toucher like you should be
able to recognise the truth in this matter philthy
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  irrelevent
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  here in Qld they do as a compliance with the law
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  how about the next time someone comes to the gate to "speak " to you
they gain entry
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  you sick drug taking meat pipe smoking retarded goose
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Re: Why are lights & GPO's on different circuits?

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Yes I possess the unfortunate name of Phil McKavity, I wish I was a dentist
as then I'd probably own a nice Porsche


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Re: Why are lights & GPO's on different circuits?

"Den"
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** Do you realise you  CHANGED  your ID  after the first post  ???

If you MUST do something as stupid as that again

-  then let us all know.



.....    Phil




Re: Why are lights & GPO's on different circuits?

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Apologies - yes I realised, we've more than 1 pc & 1 user in the house...



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