The plumber doing some work on the cylinder commented on wing the immersion
heater through a double pole switch rather than the single pole spur switch.
He mentioned the heating from the high load of the heater but I don't see
why a double pole switch will handle the heat effect better. Doesn't a
double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the consumer
unit then via a single pole switch in the kitchen and a second single pole
switch in the airing cupboard. The immersion heater is only ever used when
the boiler is out of commission for any reason.

Kevin

On 24/06/14 13:42, Kevin wrote:
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single
pole spur switch.
He mentioned the heating from the high load of the heater but I don't
see why a double pole switch will handle the heat effect better. Doesn't
a double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the
consumer unit then via a single pole switch in the kitchen and a second
single pole switch in the airing cupboard. The immersion heater is only
ever used when the boiler is out of commission for any reason.

Kevin

Normal switched fused spur is fine.

On Tuesday, June 24, 2014 1:42:43 PM UTC+1, K wrote:
The plumber doing some work on the cylinder commented on wing the immersion
heater through a double pole switch rather than the single pole spur switch.
He mentioned the heating from the high load of the heater but I don't see
why a double pole switch will handle the heat effect better. Doesn't a
double pole just switch the neutral as well?

Fused connection unit (spur switch) should also have a double pole switch anyway. However they're rated at 13 amp max and contain a cartridge fuse. The fuse contacts especially can be vulnerable to poor contact and heating from a sustained 3 kW load.

A 20 amp switch would be more robust.

Owain

On 24/06/2014 13:42, Kevin wrote:
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single
pole spur switch.
He mentioned the heating from the high load of the heater but I don't
see why a double pole switch will handle the heat effect better. Doesn't
a double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the
consumer unit then via a single pole switch in the kitchen and a second
single pole switch in the airing cupboard. The immersion heater is only
ever used when the boiler is out of commission for any reason.

Either are fine in most cases (yes the DP does just switch the N in
addition).

There is a small advantage to DP switching if the immersion is on a
circuit that shares a RCD with other circuits, since a fault heater
could cause nuisance trips via N to E leakage, so being able to fully
isolate it is handy.


--
Cheers,

John.

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

Of course it is, for many y years the cheap timer on ours worked and it was
just a single contact on the live side. I think the newer clock has a double
pole relay in it though, for whatever reason.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"Tim Watts" wrote in message
...
On 24/06/14 13:42, Kevin wrote:
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single
pole spur switch.
He mentioned the heating from the high load of the heater but I don't
see why a double pole switch will handle the heat effect better. Doesn't
a double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the
consumer unit then via a single pole switch in the kitchen and a second
single pole switch in the airing cupboard. The immersion heater is only
ever used when the boiler is out of commission for any reason.

Kevin

Normal switched fused spur is fine.

I have had to replace melted fused spur units.

I guess it is vital to go for best quality.

In article 2,
DerbyBorn writes:
I have had to replace melted fused spur units.

I guess it is vital to go for best quality.

Absolutely, and good tight connections.

If it's on a circuit which is protected by 16A MCB, don't use a
fused spur, just use a 20A switch. In this case, the 13A fuse is
doing nothing except getting hot and possibly contributing to
earlier failure...

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

"Kevin" wrote in message
...
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single pole
spur switch.
He mentioned the heating from the high load of the heater but I don't see
why a double pole switch will handle the heat effect better. Doesn't a
double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the consumer
unit then via a single pole switch in the kitchen and a second single pole
switch in the airing cupboard. The immersion heater is only ever used when
the boiler is out of commission for any reason.

Kevin

All electrical equipment must be capable of isolation and that must be
adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral
So a plug and socket would be fine. Or a double pole switch.
But not a single pole switch.
So your electric cooker, immersion heater, instantaneous electric shower,
all fixed equipment, has a double pole switch. (Or should)
It has been so for fifty years to my knowledge.

In days of yore, single pole switches were normal on sockets and "spur
switches"
Now you can get ones with double pole switches

This is why some fans need a three pole switch. L+N+control wire.

"harryagain" wrote in message
...

"Kevin" wrote in message
...
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single pole
spur switch.
He mentioned the heating from the high load of the heater but I don't see
why a double pole switch will handle the heat effect better. Doesn't a
double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the consumer
unit then via a single pole switch in the kitchen and a second single
pole switch in the airing cupboard. The immersion heater is only ever
used when the boiler is out of commission for any reason.

Kevin

All electrical equipment must be capable of isolation and that must be
adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral
So a plug and socket would be fine. Or a double pole switch.
But not a single pole switch.
So your electric cooker, immersion heater, instantaneous electric shower,
all fixed equipment, has a double pole switch. (Or should)
It has been so for fifty years to my knowledge.


I am not sure that it has ever been a requirement to switch the neutral on a
TN system and that that "requirement" is a load of ******** made up by
people talking themselves into believing it after misreading the regs.




--
Adam

On 24/06/14 20:31, ARW wrote:
"harryagain" wrote in message
...

"Kevin" wrote in message
...
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single
pole spur switch.
He mentioned the heating from the high load of the heater but I don't
see why a double pole switch will handle the heat effect better.
Doesn't a double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the
consumer unit then via a single pole switch in the kitchen and a
second single pole switch in the airing cupboard. The immersion
heater is only ever used when the boiler is out of commission for any
reason.

Kevin

All electrical equipment must be capable of isolation and that must be
adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral
So a plug and socket would be fine. Or a double pole switch.
But not a single pole switch.
So your electric cooker, immersion heater, instantaneous electric
shower, all fixed equipment, has a double pole switch. (Or should)
It has been so for fifty years to my knowledge.


I am not sure that it has ever been a requirement to switch the neutral
on a TN system and that that "requirement" is a load of ******** made up
by people talking themselves into believing it after misreading the regs.


Its fairly common practice and in SOME of the regs that SOME kit must be
totally isolatable.

That includes all bathroom kit and usually cookers and immersion heaters.

Not sure the latter is a regulation tho.





--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

"The Natural Philosopher" wrote in message
...
On 24/06/14 20:31, ARW wrote:
"harryagain" wrote in message
...

"Kevin" wrote in message
...
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single
pole spur switch.
He mentioned the heating from the high load of the heater but I don't
see why a double pole switch will handle the heat effect better.
Doesn't a double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the
consumer unit then via a single pole switch in the kitchen and a
second single pole switch in the airing cupboard. The immersion
heater is only ever used when the boiler is out of commission for any
reason.

Kevin

All electrical equipment must be capable of isolation and that must be
adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral
So a plug and socket would be fine. Or a double pole switch.
But not a single pole switch.
So your electric cooker, immersion heater, instantaneous electric
shower, all fixed equipment, has a double pole switch. (Or should)
It has been so for fifty years to my knowledge.


I am not sure that it has ever been a requirement to switch the neutral
on a TN system and that that "requirement" is a load of ******** made up
by people talking themselves into believing it after misreading the regs.


Its fairly common practice and in SOME of the regs that SOME kit must be
totally isolatable.

That includes all bathroom kit and usually cookers and immersion heaters.

Not sure the latter is a regulation tho.


The manufacturers of the equipment often say you need "Omnipolar
switching" - but you would not switch the earth would you?

The main switch of the CU is an isolator suitable for all isolation
purposes. This is local isolation that the OP is talking about. If you are
allowed to work on a circuit with a single pole MCB as the isolation why can
you not work on an appliance that is locally isolated via a single pole
device?

If a cooker switch need changing where is the isolation for the cooker
switch? On a TN system you would use the MCB for the cooker circuit - and
nothing else.

Anyway - I have proof that I am correct.

harry said "All electrical equipment must be capable of isolation and that
must be adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral So a plug and socket
would be fine. Or a double pole switch. But not a single pole switch.".

I rest my case;-)


--
Adam

On Tue, 24 Jun 2014 15:51:33 +0000 (UTC), Andrew Gabriel wrote:

I have had to replace melted fused spur units.

I guess it is vital to go for best quality.

If it's on a circuit which is protected by 16A MCB, don't use a
fused spur, just use a 20A switch. In this case, the 13A fuse is
doing nothing except getting hot and possibly contributing to
earlier failure...

+1 Hager are a decent make I believe. Didn't stop one of their
switched fused connection units going into meltdown when feeding one
of the storage heaters. All the storage heaters had SFCU's, note past
tense they all have 20A DP switches now.

--
Cheers
Dave.

On 24/06/2014 21:44, ARW wrote:
"The Natural Philosopher" wrote in message
...
On 24/06/14 20:31, ARW wrote:
"harryagain" wrote in message
...

"Kevin" wrote in message
...
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single
pole spur switch.
He mentioned the heating from the high load of the heater but I don't
see why a double pole switch will handle the heat effect better.
Doesn't a double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the
consumer unit then via a single pole switch in the kitchen and a
second single pole switch in the airing cupboard. The immersion
heater is only ever used when the boiler is out of commission for any
reason.

Kevin

All electrical equipment must be capable of isolation and that must be
adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral
So a plug and socket would be fine. Or a double pole switch.
But not a single pole switch.
So your electric cooker, immersion heater, instantaneous electric
shower, all fixed equipment, has a double pole switch. (Or should)
It has been so for fifty years to my knowledge.


I am not sure that it has ever been a requirement to switch the neutral
on a TN system and that that "requirement" is a load of ******** made up
by people talking themselves into believing it after misreading the
regs.


Its fairly common practice and in SOME of the regs that SOME kit must
be totally isolatable.

That includes all bathroom kit and usually cookers and immersion heaters.

Not sure the latter is a regulation tho.


The manufacturers of the equipment often say you need "Omnipolar
switching" - but you would not switch the earth would you?

The main switch of the CU is an isolator suitable for all isolation
purposes. This is local isolation that the OP is talking about. If you
are allowed to work on a circuit with a single pole MCB as the isolation
why can you not work on an appliance that is locally isolated via a
single pole device?

If a cooker switch need changing where is the isolation for the cooker
switch? On a TN system you would use the MCB for the cooker circuit -
and nothing else.

16th edition wording[1]:

"Except as required by Regulation 476-01-03, in TN-S or TN-C-S systems
the neutral conductor need not be isolated or switched, where the
neutral conductor can reliably be regarded as being at earth potential.
For supplies which arc provided in accordance with the Electricity
Safety, Quality and Continuity Regulations 2002, the supply neutral
conductor (PEN or N) is considered to be connected with earth by a
suitably low resistance."

There are additional requirements for isolation for items requiring
mechanical maintenance.

[1] cos I have that to hand in a PDF and can't be arsed to get the book
down from the shelf and scan it!


--
Cheers,

John.

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

On 24/06/14 21:44, ARW wrote:
"The Natural Philosopher" wrote in message
...
On 24/06/14 20:31, ARW wrote:
"harryagain" wrote in message
...

"Kevin" wrote in message
...
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single
pole spur switch.
He mentioned the heating from the high load of the heater but I don't
see why a double pole switch will handle the heat effect better.
Doesn't a double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the
consumer unit then via a single pole switch in the kitchen and a
second single pole switch in the airing cupboard. The immersion
heater is only ever used when the boiler is out of commission for any
reason.

Kevin

All electrical equipment must be capable of isolation and that must be
adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral
So a plug and socket would be fine. Or a double pole switch.
But not a single pole switch.
So your electric cooker, immersion heater, instantaneous electric
shower, all fixed equipment, has a double pole switch. (Or should)
It has been so for fifty years to my knowledge.


I am not sure that it has ever been a requirement to switch the neutral
on a TN system and that that "requirement" is a load of ******** made up
by people talking themselves into believing it after misreading the
regs.


Its fairly common practice and in SOME of the regs that SOME kit must
be totally isolatable.

That includes all bathroom kit and usually cookers and immersion heaters.

Not sure the latter is a regulation tho.


The manufacturers of the equipment often say you need "Omnipolar
switching" - but you would not switch the earth would you?

safer to have it left in place

The main switch of the CU is an isolator suitable for all isolation
purposes. This is local isolation that the OP is talking about. If you
are allowed to work on a circuit with a single pole MCB as the isolation
why can you not work on an appliance that is locally isolated via a
single pole device?

At the CU you can GUARANTEE - because its attached to the bus - that its
the live you are disconnecting..

Do you trust the sparky to have not swapped live and neutral down on a spur?


If a cooker switch need changing where is the isolation for the cooker
switch? On a TN system you would use the MCB for the cooker circuit -
and nothing else.

Anyway - I have proof that I am correct.

harry said "All electrical equipment must be capable of isolation and
that must be adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral So a plug and
socket would be fine. Or a double pole switch. But not a single pole
switch.".

I rest my case;-)


Never said Harry was right, just that you weren't 100% right either.



--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

"ARW" wrote in message
...
"The Natural Philosopher" wrote in message
...
On 24/06/14 20:31, ARW wrote:
"harryagain" wrote in message
...

"Kevin" wrote in message
...
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single
pole spur switch.
He mentioned the heating from the high load of the heater but I don't
see why a double pole switch will handle the heat effect better.
Doesn't a double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the
consumer unit then via a single pole switch in the kitchen and a
second single pole switch in the airing cupboard. The immersion
heater is only ever used when the boiler is out of commission for any
reason.

Kevin

All electrical equipment must be capable of isolation and that must be
adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral
So a plug and socket would be fine. Or a double pole switch.
But not a single pole switch.
So your electric cooker, immersion heater, instantaneous electric
shower, all fixed equipment, has a double pole switch. (Or should)
It has been so for fifty years to my knowledge.


I am not sure that it has ever been a requirement to switch the neutral
on a TN system and that that "requirement" is a load of ******** made up
by people talking themselves into believing it after misreading the
regs.


Its fairly common practice and in SOME of the regs that SOME kit must be
totally isolatable.

That includes all bathroom kit and usually cookers and immersion heaters.

Not sure the latter is a regulation tho.


The manufacturers of the equipment often say you need "Omnipolar
switching" - but you would not switch the earth would you?

The main switch of the CU is an isolator suitable for all isolation
purposes. This is local isolation that the OP is talking about. If you are
allowed to work on a circuit with a single pole MCB as the isolation why
can you not work on an appliance that is locally isolated via a single
pole device?

If a cooker switch need changing where is the isolation for the cooker
switch? On a TN system you would use the MCB for the cooker circuit - and
nothing else.


The cooker switch next to the cooker is double pole.
So the cooker can be tested and repaired.

Anyway - I have proof that I am correct.

harry said "All electrical equipment must be capable of isolation and that
must be adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral So a plug and socket
would be fine. Or a double pole switch. But not a single pole switch.".

I rest my case;-)


The reason for isoation is simple.
It is for repairs and maintenance.
How can you perform an insulation test if the neutral is still connected (to
earth)?
Also in certain (unsual) fault cases the neutral might become live.

On 25/06/2014 06:54, harryagain wrote:
"ARW" wrote in message
...
"The Natural Philosopher" wrote in message
...
On 24/06/14 20:31, ARW wrote:
"harryagain" wrote in message
...

"Kevin" wrote in message
...
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single
pole spur switch.
He mentioned the heating from the high load of the heater but I don't
see why a double pole switch will handle the heat effect better.
Doesn't a double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the
consumer unit then via a single pole switch in the kitchen and a
second single pole switch in the airing cupboard. The immersion
heater is only ever used when the boiler is out of commission for any
reason.

Kevin

All electrical equipment must be capable of isolation and that must be
adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral
So a plug and socket would be fine. Or a double pole switch.
But not a single pole switch.
So your electric cooker, immersion heater, instantaneous electric
shower, all fixed equipment, has a double pole switch. (Or should)
It has been so for fifty years to my knowledge.


I am not sure that it has ever been a requirement to switch the neutral
on a TN system and that that "requirement" is a load of ******** made up
by people talking themselves into believing it after misreading the
regs.


Its fairly common practice and in SOME of the regs that SOME kit must be
totally isolatable.

That includes all bathroom kit and usually cookers and immersion heaters.

Not sure the latter is a regulation tho.


The manufacturers of the equipment often say you need "Omnipolar
switching" - but you would not switch the earth would you?

The main switch of the CU is an isolator suitable for all isolation
purposes. This is local isolation that the OP is talking about. If you are
allowed to work on a circuit with a single pole MCB as the isolation why
can you not work on an appliance that is locally isolated via a single
pole device?

If a cooker switch need changing where is the isolation for the cooker
switch? On a TN system you would use the MCB for the cooker circuit - and
nothing else.


The cooker switch next to the cooker is double pole.
So the cooker can be tested and repaired.

There are separate and specific requirements for cooker switches however
that don't apply to immersion heaters.

As Adam highlighted, in a domestic environment you could turn off the
main switch of the CU for the purpose of isolating an immersion if
absolutely necessary.


Anyway - I have proof that I am correct.

harry said "All electrical equipment must be capable of isolation and that
must be adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral So a plug and socket
would be fine. Or a double pole switch. But not a single pole switch.".

I rest my case;-)


The reason for isoation is simple.
It is for repairs and maintenance.
How can you perform an insulation test if the neutral is still connected (to
earth)?

You disconnect the cable at the connection point or in the CU, same as
you would for any other circuit.

Also in certain (unsual) fault cases the neutral might become live.

Neutral is always a live wire, not just under fault conditions.


--
Cheers,

John.

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

"The Natural Philosopher" wrote in message
...
I am not sure that it has ever been a requirement to switch the neutral
on a TN system and that that "requirement" is a load of ******** made
up
by people talking themselves into believing it after misreading the
regs.


Its fairly common practice and in SOME of the regs that SOME kit must
be totally isolatable.

That includes all bathroom kit and usually cookers and immersion
heaters.

Not sure the latter is a regulation tho.


The manufacturers of the equipment often say you need "Omnipolar
switching" - but you would not switch the earth would you?

safer to have it left in place

The main switch of the CU is an isolator suitable for all isolation
purposes. This is local isolation that the OP is talking about. If you
are allowed to work on a circuit with a single pole MCB as the isolation
why can you not work on an appliance that is locally isolated via a
single pole device?

At the CU you can GUARANTEE - because its attached to the bus - that its
the live you are disconnecting..


Guarantee my arse. Here is one I took earllier.

eg http://wiki.diyfaq.org.uk/index.php?...dual_RCDCU.jpg

Do you trust the sparky to have not swapped live and neutral down on a
spur?

No, but you prove dead after switching off

If a cooker switch need changing where is the isolation for the cooker
switch? On a TN system you would use the MCB for the cooker circuit -
and nothing else.

Anyway - I have proof that I am correct.

harry said "All electrical equipment must be capable of isolation and
that must be adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral So a plug and
socket would be fine. Or a double pole switch. But not a single pole
switch.".

I rest my case;-)


Never said Harry was right, just that you weren't 100% right either.

My case is watertight and the photo is extra proof.

--
Adam

"harryagain" wrote in message
...

"ARW" wrote in message
...
"The Natural Philosopher" wrote in message
...
On 24/06/14 20:31, ARW wrote:
"harryagain" wrote in message
...

"Kevin" wrote in message
...
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single
pole spur switch.
He mentioned the heating from the high load of the heater but I don't
see why a double pole switch will handle the heat effect better.
Doesn't a double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the
consumer unit then via a single pole switch in the kitchen and a
second single pole switch in the airing cupboard. The immersion
heater is only ever used when the boiler is out of commission for any
reason.

Kevin

All electrical equipment must be capable of isolation and that must be
adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral
So a plug and socket would be fine. Or a double pole switch.
But not a single pole switch.
So your electric cooker, immersion heater, instantaneous electric
shower, all fixed equipment, has a double pole switch. (Or should)
It has been so for fifty years to my knowledge.


I am not sure that it has ever been a requirement to switch the neutral
on a TN system and that that "requirement" is a load of ******** made
up
by people talking themselves into believing it after misreading the
regs.


Its fairly common practice and in SOME of the regs that SOME kit must be
totally isolatable.

That includes all bathroom kit and usually cookers and immersion
heaters.

Not sure the latter is a regulation tho.


The manufacturers of the equipment often say you need "Omnipolar
switching" - but you would not switch the earth would you?

The main switch of the CU is an isolator suitable for all isolation
purposes. This is local isolation that the OP is talking about. If you
are allowed to work on a circuit with a single pole MCB as the isolation
why can you not work on an appliance that is locally isolated via a
single pole device?

If a cooker switch need changing where is the isolation for the cooker
switch? On a TN system you would use the MCB for the cooker circuit - and
nothing else.


The cooker switch next to the cooker is double pole.
So the cooker can be tested and repaired.

Anyway - I have proof that I am correct.

harry said "All electrical equipment must be capable of isolation and
that must be adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral So a plug and
socket would be fine. Or a double pole switch. But not a single pole
switch.".

I rest my case;-)


The reason for isoation is simple.
It is for repairs and maintenance.
How can you perform an insulation test if the neutral is still connected
(to earth)?

Disconnect the appliance neutral somewhere. Of course with lighting circuit
there are not usually lots of double pole switches used.

Also in certain (unsual) fault cases the neutral might become live.

Such as?

--
Adam

On 25/06/14 18:18, ARW wrote:

Guarantee my arse. Here is one I took earllier.

eg http://wiki.diyfaq.org.uk/index.php?...dual_RCDCU.jpg

So not only is the 2nd RCD polarity reversed, it's being fed by the 1st
(right) RCD?

"ARW" wrote in message
...
"harryagain" wrote in message
...

"ARW" wrote in message
...
"The Natural Philosopher" wrote in message
...
On 24/06/14 20:31, ARW wrote:
"harryagain" wrote in message
...

"Kevin" wrote in message
...
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single
pole spur switch.
He mentioned the heating from the high load of the heater but I
don't
see why a double pole switch will handle the heat effect better.
Doesn't a double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the
consumer unit then via a single pole switch in the kitchen and a
second single pole switch in the airing cupboard. The immersion
heater is only ever used when the boiler is out of commission for
any
reason.

Kevin

All electrical equipment must be capable of isolation and that must
be
adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral
So a plug and socket would be fine. Or a double pole switch.
But not a single pole switch.
So your electric cooker, immersion heater, instantaneous electric
shower, all fixed equipment, has a double pole switch. (Or should)
It has been so for fifty years to my knowledge.


I am not sure that it has ever been a requirement to switch the
neutral
on a TN system and that that "requirement" is a load of ******** made
up
by people talking themselves into believing it after misreading the
regs.


Its fairly common practice and in SOME of the regs that SOME kit must
be totally isolatable.

That includes all bathroom kit and usually cookers and immersion
heaters.

Not sure the latter is a regulation tho.


The manufacturers of the equipment often say you need "Omnipolar
switching" - but you would not switch the earth would you?

The main switch of the CU is an isolator suitable for all isolation
purposes. This is local isolation that the OP is talking about. If you
are allowed to work on a circuit with a single pole MCB as the isolation
why can you not work on an appliance that is locally isolated via a
single pole device?

If a cooker switch need changing where is the isolation for the cooker
switch? On a TN system you would use the MCB for the cooker circuit -
and nothing else.


The cooker switch next to the cooker is double pole.
So the cooker can be tested and repaired.

Anyway - I have proof that I am correct.

harry said "All electrical equipment must be capable of isolation and
that must be adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral So a plug and
socket would be fine. Or a double pole switch. But not a single pole
switch.".

I rest my case;-)


The reason for isoation is simple.
It is for repairs and maintenance.
How can you perform an insulation test if the neutral is still connected
(to earth)?

Disconnect the appliance neutral somewhere. Of course with lighting
circuit there are not usually lots of double pole switches used.

Also in certain (unsual) fault cases the neutral might become live.

Such as?

--
Adam

Wired up wrong (reverse polarity) by someone.

"harryagain" wrote in message
...

"ARW" wrote in message
...
"harryagain" wrote in message
...

"ARW" wrote in message
...
"The Natural Philosopher" wrote in message
...
On 24/06/14 20:31, ARW wrote:
"harryagain" wrote in message
...

"Kevin" wrote in message
...
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the
single
pole spur switch.
He mentioned the heating from the high load of the heater but I
don't
see why a double pole switch will handle the heat effect better.
Doesn't a double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the
consumer unit then via a single pole switch in the kitchen and a
second single pole switch in the airing cupboard. The immersion
heater is only ever used when the boiler is out of commission for
any
reason.

Kevin

All electrical equipment must be capable of isolation and that must
be
adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral
So a plug and socket would be fine. Or a double pole switch.
But not a single pole switch.
So your electric cooker, immersion heater, instantaneous electric
shower, all fixed equipment, has a double pole switch. (Or should)
It has been so for fifty years to my knowledge.


I am not sure that it has ever been a requirement to switch the
neutral
on a TN system and that that "requirement" is a load of ******** made
up
by people talking themselves into believing it after misreading the
regs.


Its fairly common practice and in SOME of the regs that SOME kit must
be totally isolatable.

That includes all bathroom kit and usually cookers and immersion
heaters.

Not sure the latter is a regulation tho.


The manufacturers of the equipment often say you need "Omnipolar
switching" - but you would not switch the earth would you?

The main switch of the CU is an isolator suitable for all isolation
purposes. This is local isolation that the OP is talking about. If you
are allowed to work on a circuit with a single pole MCB as the
isolation why can you not work on an appliance that is locally isolated
via a single pole device?

If a cooker switch need changing where is the isolation for the cooker
switch? On a TN system you would use the MCB for the cooker circuit -
and nothing else.


The cooker switch next to the cooker is double pole.
So the cooker can be tested and repaired.

Anyway - I have proof that I am correct.

harry said "All electrical equipment must be capable of isolation and
that must be adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral So a plug and
socket would be fine. Or a double pole switch. But not a single pole
switch.".

I rest my case;-)


The reason for isoation is simple.
It is for repairs and maintenance.
How can you perform an insulation test if the neutral is still connected
(to earth)?

Disconnect the appliance neutral somewhere. Of course with lighting
circuit there are not usually lots of double pole switches used.

Also in certain (unsual) fault cases the neutral might become live.

Such as?

--
Adam

Wired up wrong (reverse polarity) by someone.


That's not a fault. That's incompetence. And you prove dead before working
on a circuit or appliance.

--
Adam

On 25/06/14 19:05, ARW wrote:


That's not a fault. That's incompetence. And you prove dead before
working on a circuit or appliance.


And you prove your prover first I always test my probe on a known
live first.

ARW pretended :
Such as?

If for any reason a main neutral is lost, the the neutral will become
live.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

"Harry Bloomfield" wrote in message
. uk...
ARW pretended :
Such as?

If for any reason a main neutral is lost, the the neutral will become
live.


What is a main neutral?

--
Adam

In article ,
ARW wrote:

That's not a fault. That's incompetence. And you prove dead before
working on a circuit or appliance.

when I started updating the wiring etc in this house (wth lighting switch
in the bathroom was fed in lead sheathed cable) I found a junction box with
red & black going in and black & red coming out.

--
From KT24

Using a RISC OS computer running v5.18

"charles" wrote in message
...
In article ,
ARW wrote:

That's not a fault. That's incompetence. And you prove dead before
working on a circuit or appliance.

when I started updating the wiring etc in this house (wth lighting switch
in the bathroom was fed in lead sheathed cable) I found a junction box
with
red & black going in and black & red coming out.



Its not uncommon to find a junction box like that when you have only two red
and two black wires into the junction box.


--
Adam

In article , ARW
wrote:
"charles" wrote in message
...
In article , ARW
wrote:

That's not a fault. That's incompetence. And you prove dead before
working on a circuit or appliance.

when I started updating the wiring etc in this house (wth lighting
switch in the bathroom was fed in lead sheathed cable) I found a
junction box with red & black going in and black & red coming out.



Its not uncommon to find a junction box like that when you have only two
red and two black wires into the junction box.

you mean it's normal to join red to black and black to red inside the box?

--
From KT24

Using a RISC OS computer running v5.18

On 25/06/14 19:36, Harry Bloomfield wrote:
ARW pretended :
Such as?

If for any reason a main neutral is lost, the the neutral will become live.


This is why they have MEN on TN-C-S systems.

On 2014-06-25, ARW wrote:

"The Natural Philosopher" wrote in message
...
....
The main switch of the CU is an isolator suitable for all isolation
purposes. This is local isolation that the OP is talking about. If you
are allowed to work on a circuit with a single pole MCB as the isolation
why can you not work on an appliance that is locally isolated via a
single pole device?

At the CU you can GUARANTEE - because its attached to the bus - that its
the live you are disconnecting..


Guarantee my arse. Here is one I took earllier.

eg http://wiki.diyfaq.org.uk/index.php?...dual_RCDCU.jpg

Is there another photo after you worked on it?
;-)

"ARW" wrote in message
...
"harryagain" wrote in message
...

"ARW" wrote in message
...
"harryagain" wrote in message
...

"ARW" wrote in message
...
"The Natural Philosopher" wrote in message
...
On 24/06/14 20:31, ARW wrote:
"harryagain" wrote in message
...

"Kevin" wrote in message
...
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the
single
pole spur switch.
He mentioned the heating from the high load of the heater but I
don't
see why a double pole switch will handle the heat effect better.
Doesn't a double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the
consumer unit then via a single pole switch in the kitchen and a
second single pole switch in the airing cupboard. The immersion
heater is only ever used when the boiler is out of commission for
any
reason.

Kevin

All electrical equipment must be capable of isolation and that must
be
adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral
So a plug and socket would be fine. Or a double pole switch.
But not a single pole switch.
So your electric cooker, immersion heater, instantaneous electric
shower, all fixed equipment, has a double pole switch. (Or should)
It has been so for fifty years to my knowledge.


I am not sure that it has ever been a requirement to switch the
neutral
on a TN system and that that "requirement" is a load of ********
made up
by people talking themselves into believing it after misreading the
regs.


Its fairly common practice and in SOME of the regs that SOME kit must
be totally isolatable.

That includes all bathroom kit and usually cookers and immersion
heaters.

Not sure the latter is a regulation tho.


The manufacturers of the equipment often say you need "Omnipolar
switching" - but you would not switch the earth would you?

The main switch of the CU is an isolator suitable for all isolation
purposes. This is local isolation that the OP is talking about. If you
are allowed to work on a circuit with a single pole MCB as the
isolation why can you not work on an appliance that is locally
isolated via a single pole device?

If a cooker switch need changing where is the isolation for the cooker
switch? On a TN system you would use the MCB for the cooker circuit -
and nothing else.


The cooker switch next to the cooker is double pole.
So the cooker can be tested and repaired.

Anyway - I have proof that I am correct.

harry said "All electrical equipment must be capable of isolation and
that must be adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral So a plug and
socket would be fine. Or a double pole switch. But not a single pole
switch.".

I rest my case;-)


The reason for isoation is simple.
It is for repairs and maintenance.
How can you perform an insulation test if the neutral is still
connected (to earth)?

Disconnect the appliance neutral somewhere. Of course with lighting
circuit there are not usually lots of double pole switches used.

Also in certain (unsual) fault cases the neutral might become live.

Such as?

--
Adam

Wired up wrong (reverse polarity) by someone.


That's not a fault. That's incompetence. And you prove dead before working
on a circuit or appliance.

The most likely test to perform is insulation and you can't do that if the
appliance is still connected to neutral.

"charles" wrote in message
...
In article , ARW
wrote:
"charles" wrote in message
...
In article , ARW
wrote:

That's not a fault. That's incompetence. And you prove dead before
working on a circuit or appliance.

when I started updating the wiring etc in this house (wth lighting
switch in the bathroom was fed in lead sheathed cable) I found a
junction box with red & black going in and black & red coming out.



Its not uncommon to find a junction box like that when you have only two
red and two black wires into the junction box.

you mean it's normal to join red to black and black to red inside the box?

In days of yore there was no twin red/brown cable, so it was common in
lighting circuits.
But there was single core double sheath. cable, now disappeared.
The three terminal system of wiring was unknown too.

harryagain wrote:

there was single core double sheath. cable, now disappeared.

There is still 6241Y if you want single+earth or 6181Y if you don't want
an earth.

In article , harryagain
wrote:

"charles" wrote in message
...
In article , ARW
wrote:
"charles" wrote in message
...
In article , ARW
wrote:

That's not a fault. That's incompetence. And you prove dead before
working on a circuit or appliance.

when I started updating the wiring etc in this house (wth lighting
switch in the bathroom was fed in lead sheathed cable) I found a
junction box with red & black going in and black & red coming out.



Its not uncommon to find a junction box like that when you have only
two red and two black wires into the junction box.

you mean it's normal to join red to black and black to red inside the
box?

In days of yore there was no twin red/brown cable, so it was common in
lighting circuits.

there was twin red/black. I've still got half a drum.

But there was single core double sheath. cable, now disappeared. The
three terminal system of wiring was unknown too.

by 3 terminal, I assume you mean adding an earth - or do you mean loop
through?

--
From KT24

Using a RISC OS computer running v5.18

On 26/06/2014 05:54, harryagain wrote:


The most likely test to perform is insulation and you can't do that if the
appliance is still connected to neutral.



Of course you can, if it fails you will have to isolate it to find the
fault.

"charles" wrote in message
...
In article , harryagain
wrote:

"charles" wrote in message
...
In article , ARW
wrote:
"charles" wrote in message
...
In article , ARW
wrote:

That's not a fault. That's incompetence. And you prove dead before
working on a circuit or appliance.

when I started updating the wiring etc in this house (wth lighting
switch in the bathroom was fed in lead sheathed cable) I found a
junction box with red & black going in and black & red coming out.



Its not uncommon to find a junction box like that when you have only
two red and two black wires into the junction box.

you mean it's normal to join red to black and black to red inside the
box?

In days of yore there was no twin red/brown cable, so it was common in
lighting circuits.

there was twin red/black. I've still got half a drum.

But there was single core double sheath. cable, now disappeared. The
three terminal system of wiring was unknown too.

by 3 terminal, I assume you mean adding an earth - or do you mean loop
through?

Looping in and out of the ceiling rose. More sensible really. Might use a
little more wire.
Ie live, neutral & switch wire.

"Dennis@home" wrote in message
eb.com...
On 26/06/2014 05:54, harryagain wrote:


The most likely test to perform is insulation and you can't do that if
the
appliance is still connected to neutral.



Of course you can, if it fails you will have to isolate it to find the
fault.

It will always "fail" if connected to neutral.
Since neutral (and hence the wiring in the appliance) is connected to earth

"Tim Watts" wrote in message
...
On 25/06/14 18:18, ARW wrote:

Guarantee my arse. Here is one I took earllier.

eg http://wiki.diyfaq.org.uk/index.php?...dual_RCDCU.jpg

So not only is the 2nd RCD polarity reversed, it's being fed by the 1st
(right) RCD?


No. I have drawn on the correct connections. The only fault is that the
outgoing connections from the second RCD are the wrong way around.


https://www.youtube.com/watch?v=6TtGQNvuovE

--
Adam

ARW wrote:

"Tim Watts" wrote:

ARW wrote:

http://wiki.diyfaq.org.uk/index.php?...dual_RCDCU.jpg

So not only is the 2nd RCD polarity reversed, it's being fed by the 1st
(right) RCD?

No. I have drawn on the correct connections. The only fault is that the
outgoing connections from the second RCD are the wrong way around.

https://www.youtube.com/watch?v=6TtGQNvuovE

ITYM

http://wiki.diyfaq.org.uk/index.php?title=File:Bad_dual_RCDCU_%282%29.jpg

"Andy Burns" wrote in message
o.uk...
ARW wrote:

"Tim Watts" wrote:

ARW wrote:

http://wiki.diyfaq.org.uk/index.php?...dual_RCDCU.jpg

So not only is the 2nd RCD polarity reversed, it's being fed by the 1st
(right) RCD?

No. I have drawn on the correct connections. The only fault is that the
outgoing connections from the second RCD are the wrong way around.

https://www.youtube.com/watch?v=6TtGQNvuovE

ITYM

http://wiki.diyfaq.org.uk/index.php?title=File:Bad_dual_RCDCU_%282%29.jpg



I did:-)

--
Adam

harryagain posted

"Kevin" wrote in message
...
The plumber doing some work on the cylinder commented on wing the
immersion heater through a double pole switch rather than the single pole
spur switch.
He mentioned the heating from the high load of the heater but I don't see
why a double pole switch will handle the heat effect better. Doesn't a
double pole just switch the neutral as well?
The immersion heater circuit is a spur off of its own mcb on the consumer
unit then via a single pole switch in the kitchen and a second single pole
switch in the airing cupboard. The immersion heater is only ever used when
the boiler is out of commission for any reason.

Kevin

All electrical equipment must be capable of isolation and that must be
adjacent to it for repairs and maintenance.
Isolation means cutting off Live/phase(s) and Neutral
So a plug and socket would be fine. Or a double pole switch.
But not a single pole switch.
So your electric cooker, immersion heater, instantaneous electric shower,
all fixed equipment, has a double pole switch. (Or should)
It has been so for fifty years to my knowledge.

But why not just an ordinary plug that you can pull out from an ordinary
socket?

--
Les