On 30/05/2015 01:03, John Rumm wrote:
On 29/05/2015 19:02, dennis@home wrote:
On 29/05/2015 11:20, John Rumm wrote:

All that is required is a bit of common sense from the designer of the
circuit, and a user can do as they please.


So three 3kW heaters on the end of a ring then?

Which part about the designer using common sense did you not get?

If you have a kitchen layout like mine, all the sockets are in the
middle of the ring since there is a 20m of cable run just to get there.
If you have a CU in the kitchen then you use a bit of common sense like
if you have a pair of adjacent utility spaces close to one end of the
ring, you make sure you wire the sockets on alternate ends and not
adjacent to each other.

So you want to make it worse as the user now has no idea where the
"close to one end" sockets are?

Why not face it' you just can't cope with idiot users.


How about adding in the combi microwave at 2kW for a hour while you cook
some chicken?

So what's that going to average out at? The equivalent of 500W
continuous load?



That depends on which one and what you are cooking, they tend not to be
as well insulated as proper ovens so they use more electricity to do the
same job.

On 30/05/2015 11:06, Dave Plowman (News) wrote:
In article . com,
dennis@home wrote:
Is that how you heat your house?

Is that how anyone heats their house?

That would be 9kW of localised heat.


If that's what they please to do then why not?
John said thae can do as they please are you saying they can't?

If you actually owned 3 x 3 kW heaters it would suggest it's your only
form of heating. And space heating comes under a different set of regs.


Yet more rules that the user doesn't know!

You can't design a normal 32A 2.5mm T&E ring circuit that can't be
abused but you can blame the user it appears!

On 30/05/2015 11:03, Dave Plowman (News) wrote:
In article . com,
dennis@home wrote:
So three 3kW heaters on the end of a ring then?
How about adding in the combi microwave at 2kW for a hour while you cook
some chicken?

You have three 3kW heaters and a microwave oven in your kitchen?

It was cheaper than building that last wall...


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"Dave Plowman (News)" wrote in message
...
In article . com,
dennis@home wrote:
So three 3kW heaters on the end of a ring then?
How about adding in the combi microwave at 2kW for a hour while you cook
some chicken?

You have three 3kW heaters and a microwave oven in your kitchen?


And the induction hob that he managed to set on fire?



--
Adam

In article m,
dennis@home wrote:
If you actually owned 3 x 3 kW heaters it would suggest it's your only
form of heating. And space heating comes under a different set of regs.


Yet more rules that the user doesn't know!

You can't design a normal 32A 2.5mm T&E ring circuit that can't be
abused but you can blame the user it appears!

Sigh. If you 'abuse' it the breaker will operate.

--
*Be careful about reading health books. You may die of a misprint.

Dave Plowman London SW
To e-mail, change noise into sound.

On 30/05/2015 15:29, ARW wrote:
"Dave Plowman (News)" wrote in message
...
In article . com,
dennis@home wrote:
So three 3kW heaters on the end of a ring then?
How about adding in the combi microwave at 2kW for a hour while you cook
some chicken?

You have three 3kW heaters and a microwave oven in your kitchen?


And the induction hob that he managed to set on fire?




It was a wok, the hob was fine but you wouldn't want the truth getting
in the way of your stories would you.

On 30/05/2015 15:56, Dave Plowman (News) wrote:
In article m,
dennis@home wrote:
If you actually owned 3 x 3 kW heaters it would suggest it's your only
form of heating. And space heating comes under a different set of regs.


Yet more rules that the user doesn't know!

You can't design a normal 32A 2.5mm T&E ring circuit that can't be
abused but you can blame the user it appears!

Sigh. If you 'abuse' it the breaker will operate.


So connecting a few kW of load at one end isn't abuse?
Why the rule not to do it if its not a problem then?
You can't have it both ways, either its a problem and you can't do it or
its not a problem and you can plug what you like in where you want to.

So can you damage a final ring by plugging in loads (by design) or not?

On 30/05/2015 14:19, dennis@home wrote:
On 30/05/2015 01:03, John Rumm wrote:
On 29/05/2015 19:02, dennis@home wrote:
On 29/05/2015 11:20, John Rumm wrote:

All that is required is a bit of common sense from the designer of the
circuit, and a user can do as they please.


So three 3kW heaters on the end of a ring then?

Which part about the designer using common sense did you not get?

If you have a kitchen layout like mine, all the sockets are in the
middle of the ring since there is a 20m of cable run just to get there.
If you have a CU in the kitchen then you use a bit of common sense like
if you have a pair of adjacent utility spaces close to one end of the
ring, you make sure you wire the sockets on alternate ends and not
adjacent to each other.

So you want to make it worse as the user now has no idea where the
"close to one end" sockets are?

Den, I know this is a personal crusade of yours to convince the world
there is a problem where it is blatantly obvious that one does not
exist, but at least try and put the effort in - rather than taking the
lazy route of simply being obtuse...

I will say it again for you:

The user has no need to know what socket it where in the cable run. They
plug stuff in, it works.

Now a designer ought to think about it a bit more deeply. They need to
think about what the typical loads are going to be, what the circuit
layout will be, and what type of circuits to provision. For general
purpose socket circuits this is often a ring, but it does not have to be.

Lets say you (the designer) have decided that the kitchen is the place
where most of the high power devices are likely to be installed. The
kitchen layout has three 600mm wide under counter spaces right up
against the end wall - next to the cupboard with the CU in it. Its a
reasonable bet that a user might want to equip the space with DW, WM,
and TD - most of which will be in the 2 to 2.5kW range. So you could
potentially have 6 to 7.5kW of short term load, and say 4kW of medium
term load - close to the origin of the circuit.

So you look at the layout and decide that a ring will suite the space
well. You decide that 7.2kW total long term capacity should be adequate.
Hence you select one ring final circuit. The only thing against this
choice is that you will could end up with much of the load concentrated
at one end if you wired it without thinking it through first.

So being a sensible designer, you think "Ah, both ends of the ring will
need to pass this space", so I will equip three unswitched single
sockets under the worktop, with separate 20A plate switches above the
worktop. The first I will one I will feed at one end of the ring, and
the last pair from the other end of the ring. Thus spacing the loads
out. If you were really worried about an imbalanced load, then you might
even go so far as to place one of them on a spur taken from the origin
of the circuit.

Alternatively you might look at the kitchen and decide this is a galley
style layout - all the stuff on one wall. A more suitable topology would
be a 32A radial backbone running down the length in 4mm^2, with unfused
spurs in 2.5mm^2 cable dropping to each socket.

Why not face it' you just can't cope with idiot users.

And yet all the evidence and practical experience shows that the system
copes with users (idiot and otherwise) remarkably well.

How about adding in the combi microwave at 2kW for a hour while you
cook
some chicken?

So what's that going to average out at? The equivalent of 500W
continuous load?



That depends on which one and what you are cooking, they tend not to be
as well insulated as proper ovens so they use more electricity to do the
same job.

Thus reducing the duty cycle on the fan heaters...

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Saturday, 30 May 2015 08:54:11 UTC+1, ARW wrote:
nt wrote in message
...
On Wednesday, 27 May 2015 21:03:28 UTC+1, ARW wrote:
"GB" wrote in message
...


I did wonder whether the cable is overspecified to allow for this.
There
must be loads of ring mains with breaks or dodgy connections, but the
number of electrical fires is fairly small.


Most ring circuits are underloaded. If there is a bad connection at a
socket
then the socket usually packs up before the wiring (there may be some
small
localised wire damage).

The minimum Iz of the cable for a ring is 20A. That's the maximum a
double
socket can supply without burning out.

No, its the maximum current a double socket is rated to provide
continuously without getting hot. It takes more to burn it out.

Its the same for both. 20A is not a reserved number.

that makes no sense. I think you may have misunderstood.


NT

wrote in message
...
On Saturday, 30 May 2015 08:54:11 UTC+1, ARW wrote:
nt wrote in message
...
On Wednesday, 27 May 2015 21:03:28 UTC+1, ARW wrote:
"GB" wrote in message
...


I did wonder whether the cable is overspecified to allow for this.
There
must be loads of ring mains with breaks or dodgy connections, but
the
number of electrical fires is fairly small.


Most ring circuits are underloaded. If there is a bad connection at a
socket
then the socket usually packs up before the wiring (there may be some
small
localised wire damage).

The minimum Iz of the cable for a ring is 20A. That's the maximum a
double
socket can supply without burning out.

No, its the maximum current a double socket is rated to provide
continuously without getting hot. It takes more to burn it out.

Its the same for both. 20A is not a reserved number.

that makes no sense. I think you may have misunderstood.


No

--
Adam

"dennis@home" wrote in message
web.com...
On 30/05/2015 15:29, ARW wrote:
"Dave Plowman (News)" wrote in message
...
In article . com,
dennis@home wrote:
So three 3kW heaters on the end of a ring then?
How about adding in the combi microwave at 2kW for a hour while you
cook
some chicken?

You have three 3kW heaters and a microwave oven in your kitchen?


And the induction hob that he managed to set on fire?




It was a wok, the hob was fine but you wouldn't want the truth getting in
the way of your stories would you.


Sorry. I'll try again.

And the induction wok that you managed to set fire to.

Is that better?

The truth is it that it took you two goes to start the fire. Your first
attempt as a fire starter failed because you did not know that you
need to use a magnatic pan on an induction hob to make it work.



--
Adam

On 30/05/2015 17:21, John Rumm wrote:
On 30/05/2015 14:19, dennis@home wrote:
On 30/05/2015 01:03, John Rumm wrote:
On 29/05/2015 19:02, dennis@home wrote:
On 29/05/2015 11:20, John Rumm wrote:

All that is required is a bit of common sense from the designer of the
circuit, and a user can do as they please.


So three 3kW heaters on the end of a ring then?

Which part about the designer using common sense did you not get?

If you have a kitchen layout like mine, all the sockets are in the
middle of the ring since there is a 20m of cable run just to get there.
If you have a CU in the kitchen then you use a bit of common sense like
if you have a pair of adjacent utility spaces close to one end of the
ring, you make sure you wire the sockets on alternate ends and not
adjacent to each other.

So you want to make it worse as the user now has no idea where the
"close to one end" sockets are?

Den, I know this is a personal crusade of yours to convince the world
there is a problem where it is blatantly obvious that one does not
exist, but at least try and put the effort in - rather than taking the
lazy route of simply being obtuse...

I will say it again for you:

The user has no need to know what socket it where in the cable run. They
plug stuff in, it works.

Now a designer ought to think about it a bit more deeply. They need to
think about what the typical loads are going to be, what the circuit
layout will be, and what type of circuits to provision. For general
purpose socket circuits this is often a ring, but it does not have to be.

So a user has to know what design decisions have been made so he can
avoid doing something that compromises them.

That's the problem, you don't know what a user will do.
All you have been able to say is that typically a user wont compromise
the design but they still can, either by design or by accident.

On Saturday, 30 May 2015 17:40:56 UTC+1, ARW wrote:
wrote in message
...
On Saturday, 30 May 2015 08:54:11 UTC+1, ARW wrote:
nt wrote in message
...
On Wednesday, 27 May 2015 21:03:28 UTC+1, ARW wrote:
"GB" wrote in message
...

The minimum Iz of the cable for a ring is 20A. That's the maximum a
double
socket can supply without burning out.

No, its the maximum current a double socket is rated to provide
continuously without getting hot. It takes more to burn it out.

Its the same for both. 20A is not a reserved number.

that makes no sense. I think you may have misunderstood.


No

OK. Its obvious you misunderstood.


NT

"dennis@home" wrote in message
eb.com...
On 30/05/2015 17:21, John Rumm wrote:
On 30/05/2015 14:19, dennis@home wrote:
On 30/05/2015 01:03, John Rumm wrote:
On 29/05/2015 19:02, dennis@home wrote:
On 29/05/2015 11:20, John Rumm wrote:

All that is required is a bit of common sense from the designer of
the
circuit, and a user can do as they please.


So three 3kW heaters on the end of a ring then?

Which part about the designer using common sense did you not get?

If you have a kitchen layout like mine, all the sockets are in the
middle of the ring since there is a 20m of cable run just to get there.
If you have a CU in the kitchen then you use a bit of common sense like
if you have a pair of adjacent utility spaces close to one end of the
ring, you make sure you wire the sockets on alternate ends and not
adjacent to each other.

So you want to make it worse as the user now has no idea where the
"close to one end" sockets are?

Den, I know this is a personal crusade of yours to convince the world
there is a problem where it is blatantly obvious that one does not
exist, but at least try and put the effort in - rather than taking the
lazy route of simply being obtuse...

I will say it again for you:

The user has no need to know what socket it where in the cable run. They
plug stuff in, it works.

Now a designer ought to think about it a bit more deeply. They need to
think about what the typical loads are going to be, what the circuit
layout will be, and what type of circuits to provision. For general
purpose socket circuits this is often a ring, but it does not have to be.

So a user has to know what design decisions have been made so he can avoid
doing something that compromises them.

That's the problem, you don't know what a user will do.



Only a thick daft **** will try to use 3 x 3kW heaters and a microwave in a
kitchen.

--
Adam

wrote in message
...
On Saturday, 30 May 2015 17:40:56 UTC+1, ARW wrote:
wrote in message
...
On Saturday, 30 May 2015 08:54:11 UTC+1, ARW wrote:
nt wrote in message
...
On Wednesday, 27 May 2015 21:03:28 UTC+1, ARW wrote:
"GB" wrote in message
...

The minimum Iz of the cable for a ring is 20A. That's the maximum a
double
socket can supply without burning out.

No, its the maximum current a double socket is rated to provide
continuously without getting hot. It takes more to burn it out.

Its the same for both. 20A is not a reserved number.

that makes no sense. I think you may have misunderstood.


No

OK. Its obvious you misunderstood.


Why do you not go and **** yourself?



--
Adam

"dennis@home" wrote in message
b.com...
On 30/05/2015 15:56, Dave Plowman (News) wrote:
In article m,
dennis@home wrote:
If you actually owned 3 x 3 kW heaters it would suggest it's your only
form of heating. And space heating comes under a different set of regs.


Yet more rules that the user doesn't know!

You can't design a normal 32A 2.5mm T&E ring circuit that can't be
abused but you can blame the user it appears!

Sigh. If you 'abuse' it the breaker will operate.


So connecting a few kW of load at one end isn't abuse?
Why the rule not to do it if its not a problem then?
You can't have it both ways, either its a problem and you can't do it or
its not a problem and you can plug what you like in where you want to.

So can you damage a final ring by plugging in loads (by design) or not?

No, the design means that it will work fine. And if you get really carried
away an plug in 10 3KW heaters, the breaker or fuse will blow before
the wiring catches fire or even just melts and fails that way.

"dennis@home" wrote in message
b.com...
On 30/05/2015 11:06, Dave Plowman (News) wrote:
In article . com,
dennis@home wrote:
Is that how you heat your house?

Is that how anyone heats their house?

That would be 9kW of localised heat.


If that's what they please to do then why not?
John said thae can do as they please are you saying they can't?

If you actually owned 3 x 3 kW heaters it would suggest it's your only
form of heating. And space heating comes under a different set of regs.

Yet more rules that the user doesn't know!

The user doesn’t need to know those.

You can't design a normal 32A 2.5mm T&E ring circuit that can't be abused

It takes the abuse fine and shuts down if it can damage the ring.

but you can blame the user it appears!

On 27/05/2015 22:12, wrote:
On Wednesday, 27 May 2015 21:03:28 UTC+1, ARW wrote:
"GB" wrote in message
...


I did wonder whether the cable is overspecified to allow for this. There
must be loads of ring mains with breaks or dodgy connections, but the
number of electrical fires is fairly small.


Most ring circuits are underloaded. If there is a bad connection at a socket
then the socket usually packs up before the wiring (there may be some small
localised wire damage).

The minimum Iz of the cable for a ring is 20A. That's the maximum a double
socket can supply without burning out.

No, its the maximum current a double socket is rated to provide continuously without getting hot.

Correct, as per BS1363.

It takes more to burn it out.

That is irrelevant when it comes to design. 20A is the limit full-stop.
Anything over that and you're outside the safe working conditions and in
no mans land.

"dennis@home" wrote in message
eb.com...
On 30/05/2015 17:21, John Rumm wrote:
On 30/05/2015 14:19, dennis@home wrote:
On 30/05/2015 01:03, John Rumm wrote:
On 29/05/2015 19:02, dennis@home wrote:
On 29/05/2015 11:20, John Rumm wrote:

All that is required is a bit of common sense from the designer of
the
circuit, and a user can do as they please.


So three 3kW heaters on the end of a ring then?

Which part about the designer using common sense did you not get?

If you have a kitchen layout like mine, all the sockets are in the
middle of the ring since there is a 20m of cable run just to get there.
If you have a CU in the kitchen then you use a bit of common sense like
if you have a pair of adjacent utility spaces close to one end of the
ring, you make sure you wire the sockets on alternate ends and not
adjacent to each other.

So you want to make it worse as the user now has no idea where the
"close to one end" sockets are?

Den, I know this is a personal crusade of yours to convince the world
there is a problem where it is blatantly obvious that one does not
exist, but at least try and put the effort in - rather than taking the
lazy route of simply being obtuse...

I will say it again for you:

The user has no need to know what socket it where in the cable run. They
plug stuff in, it works.

Now a designer ought to think about it a bit more deeply. They need to
think about what the typical loads are going to be, what the circuit
layout will be, and what type of circuits to provision. For general
purpose socket circuits this is often a ring, but it does not have to be.

So a user has to know what design decisions have been made so he can avoid
doing something that compromises them.

No, because the design is robust enough to work fine
even when the user does something really stupid like
running 3 3KW heaters and the microwave in a kitchen
which is being renovated and has a ****ing great hole
in the outside wall and it’s a blizzard outside.

That's the problem, you don't know what a user will do.

And that is why the system is designed to handle say a
50A load fine for quite a while with no chance of a fire or
even the wiring insulation melting so you need to replace it.

All you have been able to say is that typically a user wont compromise the
design but they still can, either by design or by accident.

And the system handles that fine with
no risk of a fire or the insulation melting.

And if it is so flagrantly abused so that the insulation
does melt, the breaker will trip and its still completely safe.

On 30/05/2015 18:16, dennis@home wrote:
On 30/05/2015 17:21, John Rumm wrote:
On 30/05/2015 14:19, dennis@home wrote:
On 30/05/2015 01:03, John Rumm wrote:
On 29/05/2015 19:02, dennis@home wrote:
On 29/05/2015 11:20, John Rumm wrote:

All that is required is a bit of common sense from the designer of
the
circuit, and a user can do as they please.


So three 3kW heaters on the end of a ring then?

Which part about the designer using common sense did you not get?

If you have a kitchen layout like mine, all the sockets are in the
middle of the ring since there is a 20m of cable run just to get there.
If you have a CU in the kitchen then you use a bit of common sense like
if you have a pair of adjacent utility spaces close to one end of the
ring, you make sure you wire the sockets on alternate ends and not
adjacent to each other.

So you want to make it worse as the user now has no idea where the
"close to one end" sockets are?

Den, I know this is a personal crusade of yours to convince the world
there is a problem where it is blatantly obvious that one does not
exist, but at least try and put the effort in - rather than taking the
lazy route of simply being obtuse...

I will say it again for you:

The user has no need to know what socket it where in the cable run. They
plug stuff in, it works.

Now a designer ought to think about it a bit more deeply. They need to
think about what the typical loads are going to be, what the circuit
layout will be, and what type of circuits to provision. For general
purpose socket circuits this is often a ring, but it does not have to be.

So a user has to know what design decisions have been made so he can
avoid doing something that compromises them.

The user will have to trust that the designer and installer had a clue,
or else they might risk having shorter than expected service life from
their cable or sockets.

Much the same as the user will trust that the mechanic made a proper job
on the brakes of their car, or that the surgeon really does know what he
is doing.

They will need to trust that the plumber did not override the safety
interlocks on their immersion heater, and that the gas fitter remembered
to still a screw in the flue coupling on their boiler.

That's the problem, you don't know what a user will do.
All you have been able to say is that typically a user wont compromise
the design but they still can, either by design or by accident.

If you think long and hard enough you can contrive ways in which a user
can abuse any system. No circuit topology or design is immune from
abuse. Hence you have to pick a compromise that is good enough in all
likely cases.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Saturday, 30 May 2015 21:47:13 UTC+1, Fredxxx wrote:
On 27/05/2015 22:12, nt wrote:
On Wednesday, 27 May 2015 21:03:28 UTC+1, ARW wrote:
"GB" wrote in message
...


I did wonder whether the cable is overspecified to allow for this. There
must be loads of ring mains with breaks or dodgy connections, but the
number of electrical fires is fairly small.


Most ring circuits are underloaded. If there is a bad connection at a socket
then the socket usually packs up before the wiring (there may be some small
localised wire damage).

The minimum Iz of the cable for a ring is 20A. That's the maximum a double
socket can supply without burning out.

No, its the maximum current a double socket is rated to provide continuously without getting hot.

Correct, as per BS1363.

It takes more to burn it out.

That is irrelevant when it comes to design. 20A is the limit full-stop.
Anything over that and you're outside the safe working conditions and in
no mans land.

quite incorrect. Its common for 13A loads to draw well above 13A short term. All parts of ring circuits can & do handle well above their continuous current rating. It was ever so.


NT

"John Rumm" wrote in message
...
On 30/05/2015 18:16, dennis@home wrote:
On 30/05/2015 17:21, John Rumm wrote:
On 30/05/2015 14:19, dennis@home wrote:
On 30/05/2015 01:03, John Rumm wrote:
On 29/05/2015 19:02, dennis@home wrote:
On 29/05/2015 11:20, John Rumm wrote:

All that is required is a bit of common sense from the designer of
the
circuit, and a user can do as they please.


So three 3kW heaters on the end of a ring then?

Which part about the designer using common sense did you not get?

If you have a kitchen layout like mine, all the sockets are in the
middle of the ring since there is a 20m of cable run just to get
there.
If you have a CU in the kitchen then you use a bit of common sense
like
if you have a pair of adjacent utility spaces close to one end of the
ring, you make sure you wire the sockets on alternate ends and not
adjacent to each other.

So you want to make it worse as the user now has no idea where the
"close to one end" sockets are?

Den, I know this is a personal crusade of yours to convince the world
there is a problem where it is blatantly obvious that one does not
exist, but at least try and put the effort in - rather than taking the
lazy route of simply being obtuse...

I will say it again for you:

The user has no need to know what socket it where in the cable run. They
plug stuff in, it works.

Now a designer ought to think about it a bit more deeply. They need to
think about what the typical loads are going to be, what the circuit
layout will be, and what type of circuits to provision. For general
purpose socket circuits this is often a ring, but it does not have to
be.

So a user has to know what design decisions have been made so he can
avoid doing something that compromises them.

The user will have to trust that the designer and installer had a clue, or
else they might risk having shorter than expected service life from their
cable or sockets.

Much the same as the user will trust that the mechanic made a proper job
on the brakes of their car, or that the surgeon really does know what he
is doing.

They will need to trust that the plumber did not override the safety
interlocks on their immersion heater, and that the gas fitter remembered
to still a screw in the flue coupling on their boiler.

That's the problem, you don't know what a user will do.
All you have been able to say is that typically a user wont compromise
the design but they still can, either by design or by accident.

If you think long and hard enough you can contrive ways in which a user
can abuse any system. No circuit topology or design is immune from abuse.
Hence you have to pick a compromise that is good enough in all likely
cases.


A common mistake that people make when trying to design something completely
foolproof is to underestimate the ingenuity of complete fools.

So it's not fool proof it's den proof:-)





--
Adam

wrote in message
...


Its common for 13A loads to draw well above 13A short term.

I am sure that a 13A load is a 13A load.


--
Adam

On 30/05/2015 22:11, John Rumm wrote:

So a user has to know what design decisions have been made so he can
avoid doing something that compromises them.

The user will have to trust that the designer and installer had a clue,
or else they might risk having shorter than expected service life from
their cable or sockets.

But the users doesn't know the rules and may well put several high
demand loads on for days at a time, say heaters and dehumidifiers after
a flood as you appear to think no one would ever have a reason to do so.


Much the same as the user will trust that the mechanic made a proper job
on the brakes of their car, or that the surgeon really does know what he
is doing.

A mechanic doesn't install brakes that only work if the user doesn't
press them for more than 90% of the time orat least not without telling you.


They will need to trust that the plumber did not override the safety
interlocks on their immersion heater, and that the gas fitter remembered
to still a screw in the flue coupling on their boiler.

But you can't design a final ring that can't be abused by the user
either intentionally or occidentally. The fact that the regs tell you
they are unsuitable for heavy loads tells you that they aren't suitable
for heavy loads but you don't stop them from being plugged in, you just
blame the user for not knowing better.


That's the problem, you don't know what a user will do.
All you have been able to say is that typically a user wont compromise
the design but they still can, either by design or by accident.

If you think long and hard enough you can contrive ways in which a user
can abuse any system. No circuit topology or design is immune from
abuse. Hence you have to pick a compromise that is good enough in all
likely cases.

So how does a user overload a radial without the breaker tripping?
He can do that on a ring just by plugging stuff in and he may not know.

dennis@home wrote
John Rumm wrote

So a user has to know what design decisions have been made so he can
avoid doing something that compromises them.

The user will have to trust that the designer and installer had a clue,
or else they might risk having shorter than expected service life from
their cable or sockets.

But the users doesn't know the rules and may well put several high demand
loads on for days at a time, say heaters and dehumidifiers after a flood

And the ring will handle that fine if they do.

as you appear to think no one would ever have a reason to do so.

Much the same as the user will trust that the mechanic made a proper job
on the brakes of their car, or that the surgeon really does know what he
is doing.

A mechanic doesn't install brakes that only work if the user doesn't press
them for more than 90% of the time orat least not without telling you.

They do actually, most obviously with what can happen to the
brakes if you are stupid enough ride them down a very long steep
descent down a mountain range with the vehicle fully loaded etc.

They will need to trust that the plumber did not override the safety
interlocks on their immersion heater, and that the gas fitter remembered
to still a screw in the flue coupling on their boiler.

But you can't design a final ring that can't be abused by the user either
intentionally or occidentally.

That's why its designed to work fine when abused.

The fact that the regs tell you they are unsuitable for heavy loads tells
you that they aren't suitable for heavy loads but you don't stop them from
being plugged in, you just blame the user for not knowing better.

The breaker ensures that if too many heavy loads are used, the
system shuts down so that the wire insulation doesn’t start melting.

That's the problem, you don't know what a user will do.
All you have been able to say is that typically a user wont compromise
the design but they still can, either by design or by accident.

If you think long and hard enough you can contrive ways in which a user
can abuse any system. No circuit topology or design is immune from
abuse. Hence you have to pick a compromise that is good enough in all
likely cases.

So how does a user overload a radial without the breaker tripping?

Same way they do with a ring.

He can do that on a ring just by plugging stuff in

Same with a radial with GPOs, just like with a ring.

and he may not know.

Doesn’t need to. The breaker ensures that the insulation wont
be melted and if he is actually stupid enough to point all those
3K heaters directly at the wall which has the wiring in it and
manages to melt the insulation that way, the breaker will
trip and prevent the house catching fire. Corse in that situation
the wall itself may well catch fire but then the alarm will go off
and the occupants can do what they like about that fire.

And if they have been stupid enough to leave the house with
all those heaters directly pointed at the flammible wall, the
building regulations ensure that anyone left in that house
can still get out and that even if the house does burn down,
that wont set fire to anyone else's house.

On Saturday, 30 May 2015 23:02:12 UTC+1, ARW wrote:
nt wrote in message
...


Its common for 13A loads to draw well above 13A short term.

I am sure that a 13A load is a 13A load.

Then you've got something to learn about heating elements and motors

Its the same mentality as people that think a 3A fuse pops at 3.0001A insantly.


NT

"dennis@home" wrote in message
web.com...
On 30/05/2015 22:11, John Rumm wrote:

So a user has to know what design decisions have been made so he can
avoid doing something that compromises them.

The user will have to trust that the designer and installer had a clue,
or else they might risk having shorter than expected service life from
their cable or sockets.

But the users doesn't know the rules and may well put several high demand
loads on for days at a time, say heaters and dehumidifiers after a flood
as you appear to think no one would ever have a reason to do so.

Not 9kW.



--
Adam

In article . com,
dennis@home wrote:
But the users doesn't know the rules and may well put several high
demand loads on for days at a time, say heaters and dehumidifiers after
a flood as you appear to think no one would ever have a reason to do so.

The UK 13 amp ring had been around for over 60 years. At one point - long
before central heating was the norm - it was also common to have just one
ring for the entire house.

Yet no one seems to have found the problems with it you seem to
anticipate. Wonder why?

--
*The statement below is true.

Dave Plowman London SW
To e-mail, change noise into sound.

wrote in message
...
On Saturday, 30 May 2015 23:02:12 UTC+1, ARW wrote:
nt wrote in message
...


Its common for 13A loads to draw well above 13A short term.

I am sure that a 13A load is a 13A load.

Then you've got something to learn about heating elements and motors

Its the same mentality as people that think a 3A fuse pops at 3.0001A
insantly.


Maybe you should learn the difference between a short term overload and an
inrush current.

--
Adam

On 31/05/2015 09:40, ARW wrote:
"dennis@home" wrote in message
web.com...
On 30/05/2015 22:11, John Rumm wrote:

So a user has to know what design decisions have been made so he can
avoid doing something that compromises them.

The user will have to trust that the designer and installer had a clue,
or else they might risk having shorter than expected service life from
their cable or sockets.

But the users doesn't know the rules and may well put several high
demand loads on for days at a time, say heaters and dehumidifiers
after a flood as you appear to think no one would ever have a reason
to do so.

Not 9kW.




I have seen about 15kW used like that. No idea what they were plugged
into. 5 or 6 fan heaters and the windows open to get rid of the moist
air. Something to do with the people moving in the following day and the
floor screed having been ripped up and relayed.

I have loads of building related horror stories being friends with the
head of building control. I have been around one site where about 20
houses had all developed cracks and were slowly moving down a slope
after less than six months. One where the lean to was assembled from
concrete blocks with nothing in between them, just waiting for a windy day.

On 31/05/2015 11:11, Dave Plowman (News) wrote:
In article . com,
dennis@home wrote:
But the users doesn't know the rules and may well put several high
demand loads on for days at a time, say heaters and dehumidifiers after
a flood as you appear to think no one would ever have a reason to do so.

The UK 13 amp ring had been around for over 60 years. At one point - long
before central heating was the norm - it was also common to have just one
ring for the entire house.


Back in the days when a heater would have cost a weeks wages and not £10
in asda.
People back then wouldn't have had more than one or two heaters to use.

Come to think of it what did we have in the 50's.. one single bar
electric fire and a portable gas heater that plugged into a bayonet gas
connector in different rooms.
Oh and coal fires.

Yet no one seems to have found the problems with it you seem to
anticipate. Wonder why?


Because nobody investigates the problems and when they do they say it
was installed to the regs so its the users fault.

In article om,
dennis@home wrote:
The UK 13 amp ring had been around for over 60 years. At one point - long
before central heating was the norm - it was also common to have just one
ring for the entire house.


Back in the days when a heater would have cost a weeks wages and not £10
in asda.
People back then wouldn't have had more than one or two heaters to use.

Notice you've missed the point that houses these days have usually got
some form of built in heating. And usually more than one ring. The only
place most houses use a lot of plugged in power is in the kitchen, and
sensible people fit a separate ring, or even two, there.

Come to think of it what did we have in the 50's.. one single bar
electric fire and a portable gas heater that plugged into a bayonet gas
connector in different rooms.

You must have been very poor.

Oh and coal fires.

And think of the vast numbers they killed.

Yet no one seems to have found the problems with it you seem to
anticipate. Wonder why?


Because nobody investigates the problems and when they do they say it
was installed to the regs so its the users fault.

That's because the 'problems' are in your mind, not reality.

--
*Your kid may be an honours student, but you're still an idiot.

Dave Plowman London SW
To e-mail, change noise into sound.

"dennis@home" wrote in message
web.com...
On 31/05/2015 09:40, ARW wrote:
"dennis@home" wrote in message
web.com...
On 30/05/2015 22:11, John Rumm wrote:

So a user has to know what design decisions have been made so he can
avoid doing something that compromises them.

The user will have to trust that the designer and installer had a clue,
or else they might risk having shorter than expected service life from
their cable or sockets.

But the users doesn't know the rules and may well put several high
demand loads on for days at a time, say heaters and dehumidifiers
after a flood as you appear to think no one would ever have a reason
to do so.

Not 9kW.




I have seen about 15kW used like that. No idea what they were plugged
into. 5 or 6 fan heaters and the windows open to get rid of the moist air.

They were using a dehumidifier 3 hours ago.

--
Adam

"dennis@home" wrote in message
news:556ae132$0$61678$b1db1813
I have loads of building related horror stories being friends with the
head of building control.

And was this friend the one that told you that you needed planning
permission to install two satellite dishes?

--
Adam

On Sunday, 31 May 2015 11:18:47 UTC+1, ARW wrote:
nt wrote in message
...
On Saturday, 30 May 2015 23:02:12 UTC+1, ARW wrote:
nt wrote in message
...


Its common for 13A loads to draw well above 13A short term.

I am sure that a 13A load is a 13A load.

Then you've got something to learn about heating elements and motors

Its the same mentality as people that think a 3A fuse pops at 3.0001A
insantly.


Maybe you should learn the difference between a short term overload and an
inrush current.

The point dear chap is that there are circumstances under which motors draw a good deal more than their rated current, eg when overloaded, stalled, bearings misbehaving etc. The assertion that 13A loads always draw 13A is just naive, ditto the notion that if you draw anything over 20A from a double socket it catches fire.

I've seen so many criticisms of ring circuits and they always come down to failing to grasp quite basic concepts. Things like the difference between rated current and actual ability, complete failure to grasp what effect exceeding continuous current rating has, and in Mr. Lovegrove's case, failing to notice that his criticisms of rings are in fact advantages compared to radials.


NT

wrote in message
...
On Sunday, 31 May 2015 11:18:47 UTC+1, ARW wrote:
nt wrote in message
...
On Saturday, 30 May 2015 23:02:12 UTC+1, ARW wrote:
nt wrote in message
...


Its common for 13A loads to draw well above 13A short term.

I am sure that a 13A load is a 13A load.

Then you've got something to learn about heating elements and motors

Its the same mentality as people that think a 3A fuse pops at 3.0001A
insantly.


Maybe you should learn the difference between a short term overload and an
inrush current.

The point dear chap is that there are circumstances under which motors draw
a good deal more than their rated current, eg when overloaded, stalled,
bearings misbehaving etc. The assertion that 13A loads always draw 13A is
just naive, ditto the notion that if you draw anything over 20A from a
double socket it catches fire.

I've seen so many criticisms of ring circuits and they always come down to
failing to grasp quite basic concepts. Things like the difference between
rated current and actual ability, complete failure to grasp what effect
exceeding continuous current rating has, and in Mr. Lovegrove's case,
failing to notice that his criticisms of rings are in fact advantages
compared to radials.



I know far more about electrical installations than you.

Go **** yourself

--
Adam

On Sunday, 31 May 2015 14:55:28 UTC+1, ARW wrote:
nt wrote in message
...
On Sunday, 31 May 2015 11:18:47 UTC+1, ARW wrote:
nt wrote in message
...
On Saturday, 30 May 2015 23:02:12 UTC+1, ARW wrote:
nt wrote in message
...


Its common for 13A loads to draw well above 13A short term.

I am sure that a 13A load is a 13A load.

Then you've got something to learn about heating elements and motors

Its the same mentality as people that think a 3A fuse pops at 3.0001A
insantly.


Maybe you should learn the difference between a short term overload and an
inrush current.

The point dear chap is that there are circumstances under which motors draw
a good deal more than their rated current, eg when overloaded, stalled,
bearings misbehaving etc. The assertion that 13A loads always draw 13A is
just naive, ditto the notion that if you draw anything over 20A from a
double socket it catches fire.

I've seen so many criticisms of ring circuits and they always come down to
failing to grasp quite basic concepts. Things like the difference between
rated current and actual ability, complete failure to grasp what effect
exceeding continuous current rating has, and in Mr. Lovegrove's case,
failing to notice that his criticisms of rings are in fact advantages
compared to radials.



I know far more about electrical installations than you.

Go **** yourself

From the guy that said a socket would catch fire if it passed anything over 20A.

In article ,
wrote:
From the guy that said a socket would catch fire if it passed anything
over 20A.

If you bypassed the plug fuse and loaded up the socket to 20A continuous
I'd not be surprised if it eventually caught fire or melted. Or the plug
would, of course.

--
*Cleaned by Stevie Wonder, checked by David Blunkett*

Dave Plowman London SW
To e-mail, change noise into sound.

On 31/05/2015 11:40, Dave Plowman (News) wrote:
In article om,
dennis@home wrote:
The UK 13 amp ring had been around for over 60 years. At one point - long
before central heating was the norm - it was also common to have just one
ring for the entire house.


Back in the days when a heater would have cost a weeks wages and not £10
in asda.
People back then wouldn't have had more than one or two heaters to use.

Notice you've missed the point that houses these days have usually got
some form of built in heating. And usually more than one ring. The only
place most houses use a lot of plugged in power is in the kitchen, and
sensible people fit a separate ring, or even two, there.

There is no point to miss.
You still think rings are safe because people don't do things that
compromise them. You haven't shown that they can't be compromised as you
can't show that despite Rod supporting you.

You may as well say they can have a radial with 2.5 mm cable and a 40A
breaker as they are only going to plug a few phone chargers in it.
Its safe because they aren't going to overload it according to your
logic. You also think you can make it safer by having more than one of them.

On 31/05/2015 12:54, ARW wrote:
"dennis@home" wrote in message
web.com...
On 31/05/2015 09:40, ARW wrote:
"dennis@home" wrote in message
web.com...
On 30/05/2015 22:11, John Rumm wrote:

So a user has to know what design decisions have been made so he can
avoid doing something that compromises them.

The user will have to trust that the designer and installer had a
clue,
or else they might risk having shorter than expected service life from
their cable or sockets.

But the users doesn't know the rules and may well put several high
demand loads on for days at a time, say heaters and dehumidifiers
after a flood as you appear to think no one would ever have a reason
to do so.

Not 9kW.




I have seen about 15kW used like that. No idea what they were plugged
into. 5 or 6 fan heaters and the windows open to get rid of the moist
air.

They were using a dehumidifier 3 hours ago.


They didn't have easy access to dehumidifiers 30 years ago. They did
have spurs with more than one socket on them though so they could have
been on a spur for all you know. That would have been fine though as it
was permitted in the regs.