[McKavity]

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?

 

[terryc]

Kid's school science question as per subject line.

Anyone got any answers -

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.

 

[Phil Allison]

"McKavity"

Kid's school science question as per subject line.

Anyone got any answers -

** 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

 

[David L. Jones]

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?

Lights need to stay operational in the event of appliance overloading
(which can be fairly common), so it makes sense from that safety
perspective.

Also, when electricity was first introduced, I believe lighting was
the only application. Light wiring would have been low current
capacity, so when higher current power points were added later it was
most likely essential to put them on a new separate circuit.
And hence it remained for ever more.

Dave.

 

[Den]

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.

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

 

[Den]

"McKavity"



** 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
ghting - 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

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.
\

 

[Den]

Lights need to stay operational in the event of appliance overloading
(which can be fairly common), so it makes sense from that safety
perspective.

Also, when electricity was first introduced, I believe lighting was
the only application. Light wiring would have been low current
capacity, so when higher current power points were added later it was
most likely essential to put them on a new separate circuit.
And hence it remained for ever more.

Dave.

Cheers Dave.

PS dont you, pa & some of the other regulars here ever go to sleep!

 

[David]

"McKavity"



** 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.

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

 

[Davo]

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?

The Australian wiring rules require that there be (at least) two
circuits for lighting and two for GPOs.

Main reason is safety. So you're not left in the dark, and you have
always have some power.

Lighting circuits not only have lower current rating fuses but also
lower current rated wire.

Earth wiring has to be supplied to light fittings whether the lights
need an earth connection or not.

Safety is everything in the wiring rules. Wiring rules were initiated by
insurance companies.

 

[David]

The Australian wiring rules require that there be (at least) two
circuits for lighting and two for GPOs.

Not true under current rules, and never has been.

The old rules strongly encouraged at least two power circuits in
domestic installations, by severely limiting the number of GPOs (as they
were called in those days) allowed for an installation with only one
circuit, but it was not compulsory.

New rules (AS/NZS3000:2007) leave it to the designer and cover it under
the General Design of an Electrical Installation : Rule 1.6.1 (d) -
minimize inconvenience in the event of a fault, and Rule 1.6.5 - Every
electrical installation shall be divided into circuits as necessary to -
(a) avoid danger and minimize inconvenience in the event of a fault; and
(b) facilitate safe operation, inspection, testing and maintenance.


There has never been a requirement for at least two lighting circuits.

David

 

[Phil Allison]

"David L Jerkoff"

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.

** Any such rule ONLY applies to NEW installations in new premises after
the creation of the rule.

So has got **** ALL to do with my comments or the OP's question.

The main reason for separate lights and power is cost.

** That is ABSOLUTE BOLLOCKS !!!!!!!!

The actual reasons are just as I stated above - which YOU AGREED WITH
only a few hours ago, right here.

You COLOSSALLY AUTISTIC COMPEWTER GEEK MORON.




...... Phil

 

[Phil Allison]

"Davo the Dickhead "

The Australian wiring rules require that there be (at least) two circuits
for lighting and two for GPOs.

** Absolute BOLLOCKS !

Main reason is safety. So you're not left in the dark, and you have always
have some power.

** Tell that to MILLIONS of folk who currently occupy residential premises
with only ONE of each.

Dickhead !!!

Earth wiring has to be supplied to light fittings whether the lights need
an earth connection or not.

** BOLLOCKS.

Safety is everything in the wiring rules.

** MORE BOLLOCKS !!!!!!!!!!!!!!!!!

Explain why in NSW there is NO requirement for the installation of an
RCD in domestic premises - either after the ownership changes hands or
after a full re-wiring of the premises is done.

Dickhead.

Wiring rules were initiated by insurance companies.

** Who have no interest in electrocution risk WHATEVER.

Cos the fucking pricks do not cover that.

Dickhead.



...... Phil

 

[David L. Jones]

"David L Jerkoff"

At least get your childish insults correct Phil, that wasn't my post.

Dave.

 

[David]

** BOLLOCKS.

Wrong again Phil, AS/NZS3000:2007 Rule 5.4.3 clearly states that an
Earth wire needs to be supplied at lighting points. Been that way since
at least 1991 rules.

** MORE BOLLOCKS !!!!!!!!!!!!!!!!!

Explain why in NSW there is NO requirement for the installation of
an RCD in domestic premises - either after the ownership changes
hands or after a full re-wiring of the premises is done.

Dickhead.

You really need to learn to *read* the Standard Phil. The rules clearly
state that any alterations or additions to an existing installation are
required to meet the relevant provisions of the current standard. Only
repairs to existing installations may be carried out using the standard
applicable at the time of the original installation.

Clearly a full re-wiring would be a new installation, and require RCDs.


David

 

[John Tserkezis]

New rules (AS/NZS3000:2007) leave it to the designer and cover it under
the General Design of an Electrical Installation : Rule 1.6.1 (d) -
minimize inconvenience in the event of a fault, and Rule 1.6.5 - Every
electrical installation shall be divided into circuits as necessary to -
(a) avoid danger and minimize inconvenience in the event of a fault; and
(b) facilitate safe operation, inspection, testing and maintenance.

You're the first to mention *inconvenience* (as well as danger) when losing
power.

I never bought the safety bullshit angle. We've lost power due to blackouts
numerous times, and the ONLY safety issue was getting bored to death by lack
of television, and lately, perhaps lack of a computer and internet connection.
Complete blackouts aren't unheard of, even some of the more major *cities*
here in Australia still have regular blackouts (even if that IS another story).

I don't know about others, but I have torches within easy reach of a couple
of rooms.
I still don't buy the safety bullshit angle. What's going happen? Some old
fart will fall over in the dark? Or is it a surprise the old fart didn't keel
over when they stuck their knife in the toaster which caused the power loss in
the first place?


Or have they never heard of candles and kerosine lamps like they used to use
in the 'olde days before electrickery?
Or is the safety angle just that? The risk of fire of candles and kerosine
lamps the reason everyone says electricity is "safe"?
Though, it HAS been nearly two entire generations since kero lamps have
vanished, and candles have been redelagated to the task of aromatherapy.

That's like saying it's safe to use wired electricity in the house because
cave people used to light indoors fires and burn their bloody caves down.

 

[David]

"David L Jerkoff"


** Any such rule ONLY applies to NEW installations in new premises after
the creation of the rule.

Wrong. The rule applies to any alterations and additions as well as new
installations. This applies to new *AND EXISTING* premises. The earthing
of luminares has been in the rules for a long time.

So has got **** ALL to do with my comments or the OP's question.

Your comment in clearly wrong and very misleading. Typical lighting
circuits would have earth conductors. Only very old circuits would not.

** That is ABSOLUTE BOLLOCKS !!!!!!!!

The actual reasons are just as I stated above - which YOU AGREED WITH
only a few hours ago, right here.

Ugh? As the previous post was my first post on this subject, that is
again incorrect. Which post are you referring to?

You COLOSSALLY AUTISTIC COMPEWTER GEEK MORON.

Wrong again. Unlike you, I am a fully licensed electrical contractor, so
I do know what I am on about. I also have copies of and have read and
understand the current wiring rules. Might be a good idea if you did the
same before you post again.


David

 

[David]

You're the first to mention *inconvenience* (as well as danger) when
losing power.

Current rules require at least two RCDs in a domestic installation
(unless there is only one circuit). Also, to mimimize the impact of an
operation of a single RCD, a maximum of three final sub circuits shall
be protected by one RCD, and lighting circuits shall be distributed
between RCDs

I never bought the safety bullshit angle. We've lost power due to
blackouts numerous times, and the ONLY safety issue was getting bored to
death by lack of television, and lately, perhaps lack of a computer and
internet connection.
Complete blackouts aren't unheard of, even some of the more major
*cities* here in Australia still have regular blackouts (even if that IS
another story).

And will only get more frequent, with no new power stations being built
in NSW.

I don't know about others, but I have torches within easy reach of a
couple of rooms.

If there is a danger, you could fit battery operated emergency lights.
These are required in most public and non residential buildings.

I still don't buy the safety bullshit angle. What's going happen?
Some old fart will fall over in the dark? Or is it a surprise the old
fart didn't keel over when they stuck their knife in the toaster which
caused the power loss in the first place?


Or have they never heard of candles and kerosine lamps like they used
to use in the 'olde days before electrickery?
Or is the safety angle just that? The risk of fire of candles and
kerosine lamps the reason everyone says electricity is "safe"?
Though, it HAS been nearly two entire generations since kero lamps have
vanished, and candles have been redelagated to the task of aromatherapy.

That's like saying it's safe to use wired electricity in the house
because cave people used to light indoors fires and burn their bloody
caves down.

David

 

[John Tserkezis]

And will only get more frequent, with no new power stations being built
in NSW.

No matter, there is more than enough work in this area on for everyone
concerned when it comes to the rest of the country. And around the world...

If there is a danger, you could fit battery operated emergency lights.
These are required in most public and non residential buildings.

When the government can fund and fit those #%&!^# CFLs to everyone's place,
all for no more than single digit percentage savings, why can't they supply a
cheap torch (with batteries supplied!!) and really improve things?

 

[David L. Jones]

Wrong. The rule applies to any alterations and additions as well as new
installations. This applies to new *AND EXISTING* premises. The earthing
of luminares has been in the rules for a long time.




Your comment in clearly wrong and very misleading. Typical lighting
circuits would have earth conductors. Only very old circuits would not.






Ugh? As the previous post was my first post on this subject, that is
again incorrect. Which post are you referring to?

He was referring to my post.
Phil was too busy frothing at the mouth in haste to insult someone to
notice it was you instead of me.
He must be low on medication today.

Dave.

 

[Phil Allison]

"David L. Jones"
"Phil Allison"

At least get your childish insults correct Phil, that wasn't my post.

** Too many Daves in this tread.




...... Phil