I was in hosue last week. The Spark said all you need do to bond is
for the upstairs, take an earth wire from the meter to the bathroom
light earth terminal then the switch, then the pipes under bath taps,
jump from one to the other, then to the basin taps, as per bath and
then to radiator copper tails and stop.

For downstairs, an earth wire from the meter to the pipes of the
boiler in the kitchen, just linking each boiler pipe under the boiler
an then stop. None on the sink taps, pipe under the sink or to the
ligh fittings or switch.

Then from the meter earth block to the gas pipe at the meter and the
water pipe as it comes into the house.

Sounds right as a guide?

In article .com,
wrote:
I was in hosue last week. The Spark said all you need do to bond is
for the upstairs, take an earth wire from the meter to the bathroom
light earth terminal then the switch, then the pipes under bath taps,
jump from one to the other, then to the basin taps, as per bath and
then to radiator copper tails and stop.

For downstairs, an earth wire from the meter to the pipes of the
boiler in the kitchen, just linking each boiler pipe under the boiler
an then stop. None on the sink taps, pipe under the sink or to the
ligh fittings or switch.

Then from the meter earth block to the gas pipe at the meter and the
water pipe as it comes into the house.

Sounds right as a guide?

No. Try talking to a spark who actually understands the regs. Your one
sounds like the equivalent of dribble.

Plenty books on the subject. One such he-

http://www.tlc-direct.co.uk/Products/BKSNA1.html

--
*Virtual reality is its own reward *

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

wrote:

I was in hosue last week. The Spark said all you need do to bond is
for the upstairs, take an earth wire from the meter to the bathroom
light earth terminal then the switch, then the pipes under bath taps,
jump from one to the other, then to the basin taps, as per bath and
then to radiator copper tails and stop.

For downstairs, an earth wire from the meter to the pipes of the
boiler in the kitchen, just linking each boiler pipe under the boiler
an then stop. None on the sink taps, pipe under the sink or to the
ligh fittings or switch.

Then from the meter earth block to the gas pipe at the meter and the
water pipe as it comes into the house.

Sounds right as a guide?

Not quite, he seems to have lost the plot somewhere along the way.

With bathrooms you are simply attempting to create an supplementary
equipotential zone. This involves connecting together all exposed
metalwork that has the capability of introducing a potential into the
zone. So basically metal pipes (supply or waste), any exposed building
metalwork (unlikely in a domestic place), and the CPCs of any circuits
supplying the room (which would include potentially ring or radial
circuits feeding appliances, and shower feeds etc). Where appliances are
present you may make use of the CPC supplying it as a bonding conductor.
There is *no* requirement for a dedicated connection to the main earth
terminal.

Kitchens do not actually need supplementary equipotential bonding at all
since they are not "special locations".

Both of the above are separate from the requirements to provide main
equipotential bonds between incoming services. The main bonding should
include the CH system, which may or may not be in the kitchen. The
required cable sizes are different from those used for supplementary
bonding as well.


--
Cheers,

John.

/================================================== ===============\
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|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:
wrote:

I was in hosue last week. The Spark said all you need do to bond is
for the upstairs, take an earth wire from the meter to the bathroom
light earth terminal then the switch, then the pipes under bath taps,
[...]
Sounds right as a guide?

Not quite, he seems to have lost the plot somewhere along the way.

Maybe there are different regs in this mysterious place Hosue...

Both of the above are separate from the requirements to provide main
equipotential bonds between incoming services. The main bonding should
include the CH system, which may or may not be in the kitchen. The
required cable sizes are different from those used for supplementary
bonding as well.

What I've just done is to apply main bonding between elec meter/gas
meter/rising main (the latter not being in the kitchen); then separately
in the kitchen applied supplementary bonding between kitchen sink/taps
and the gas pipe, CH flow and return at the adjacent boiler.

I appreciate that kitchen supplementary bonding isn't a requirement (but
the sparks who does my testing insists on it so I just don't argue!) but
does my scheme 'work' OK in terms of the CH system?

David

Lobster wrote:

What I've just done is to apply main bonding between elec meter/gas
meter/rising main (the latter not being in the kitchen); then separately
in the kitchen applied supplementary bonding between kitchen sink/taps
and the gas pipe, CH flow and return at the adjacent boiler.

I appreciate that kitchen supplementary bonding isn't a requirement (but
the sparks who does my testing insists on it so I just don't argue!) but
does my scheme 'work' OK in terms of the CH system?

It works ok[1], but is not quite to the letter of the regs...

[1] how well depends a bit on the plumbing.

--
Cheers,

John.

/================================================== ===============\
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|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:
Lobster wrote:

What I've just done is to apply main bonding between elec meter/gas
meter/rising main (the latter not being in the kitchen); then
separately in the kitchen applied supplementary bonding between
kitchen sink/taps and the gas pipe, CH flow and return at the adjacent
boiler.

I appreciate that kitchen supplementary bonding isn't a requirement
(but the sparks who does my testing insists on it so I just don't
argue!) but does my scheme 'work' OK in terms of the CH system?

It works ok[1], but is not quite to the letter of the regs...

Good! So ideally what should I do, or should have done? (it's going to
be inspected soon so would be good to know*)

[1] how well depends a bit on the plumbing.

Copper throughout, with soldered joints.

David

*Ended up cancelling last week's inspection mentioned in a different thread!

Lobster wrote:
John Rumm wrote:
Lobster wrote:

What I've just done is to apply main bonding between elec meter/gas
meter/rising main (the latter not being in the kitchen); then
separately in the kitchen applied supplementary bonding between
kitchen sink/taps and the gas pipe, CH flow and return at the
adjacent boiler.

I appreciate that kitchen supplementary bonding isn't a requirement
(but the sparks who does my testing insists on it so I just don't
argue!) but does my scheme 'work' OK in terms of the CH system?

It works ok[1], but is not quite to the letter of the regs...

Good! So ideally what should I do, or should have done? (it's going to
be inspected soon so would be good to know*)

Connection from the main earth terminal in 10mm^2 yellow/green single to
the main incoming services and any "extraneous conductive parts".

BS7671 spells it out as:

413-02-02 In each installation main equipotential bonding conductors
complying with Section 547 shall connect to the main earthing terminal
extraneous-conductive-parts of that installation including the following:

(i) water service pipes
(ii) gas installation pipes
(iii) other service pipes and ducting
(iv) central heating and air conditioning systems
(v) exposed metallic structural parts of the building
(vi) the lightning protective system.
Where an installation serves more than one building the above
requirement shall be applied to each building.


547-02 Main equipotential bonding conductors
547-02-01 Except where PME conditions apply, a main equipotential
bonding conductor shall have a
cross-sectional area not less than half the cross-sectional area
required for the earthing conductor of the installation
and not less than 6 mm2. The cross-sectional area need not exceed 25 mm2
if the bonding conductor is of copper or a
cross-sectional area affording equivalent conductance in other metals.
Where PME conditions apply, the main equipotential bonding conductor
shall be selected in accordance with the
neutral conductor of the supply and Table 54H.

(and 54H says 10mm for a supply neutral of 35mm^2 or less.)

--
Cheers,

John.

/================================================== ===============\
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|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:
Lobster wrote:
John Rumm wrote:
Lobster wrote:

What I've just done is to apply main bonding between elec meter/gas
meter/rising main (the latter not being in the kitchen); then
separately in the kitchen applied supplementary bonding between
kitchen sink/taps and the gas pipe, CH flow and return at the
adjacent boiler.

I appreciate that kitchen supplementary bonding isn't a requirement
(but the sparks who does my testing insists on it so I just don't
argue!) but does my scheme 'work' OK in terms of the CH system?

It works ok[1], but is not quite to the letter of the regs...

Good! So ideally what should I do, or should have done? (it's going
to be inspected soon so would be good to know*)

Connection from the main earth terminal in 10mm^2 yellow/green single to
the main incoming services and any "extraneous conductive parts".

Hmm, thanks, hadn't realised that one. OK, so if my spark's feeling
particulary anal, then to connect the boiler to electric meter would
require a new 10mm^2 earth cable right through the house (which would
necessitate a lot of destruction of freshly plastered surfaces - not great.)

Would it be allowable to run a short (new) cable from the exisiting
earthing clamp on the rising main as far as the nearest CH pipes (which
is a long way from the boiler; and would the earth route from the CH
back to the electric incomer would be via a non-continous cable)?

Thanks
David

Lobster wrote:

Connection from the main earth terminal in 10mm^2 yellow/green single
to the main incoming services and any "extraneous conductive parts".

Hmm, thanks, hadn't realised that one. OK, so if my spark's feeling
particulary anal, then to connect the boiler to electric meter would
require a new 10mm^2 earth cable right through the house (which would
necessitate a lot of destruction of freshly plastered surfaces - not
great.)

Might be worth asking him. Since the extraneous conductive paths in this
case have no "entry point" into the property, one could argue that there
is no requirement to make the connection at the boiler. (other than that
being a place where you can be reasonably assured the pipes will go)

Would it be allowable to run a short (new) cable from the exisiting
earthing clamp on the rising main as far as the nearest CH pipes (which
is a long way from the boiler; and would the earth route from the CH
back to the electric incomer would be via a non-continous cable)?

I believe it should be unbroken[1], but I am not sure if that is
actually a hard requirement. There is no reason that the conductor has
to pass round the inside of the house either. You may well find that the
presence of supplementary bonding on the boiler connections (even if not
actually required), may satisfy an inspection. The primary thing that
one would be looking for is a connection to the water and gas mains in
most cases.

[1] The on site guide makes reference to "unbroken" conductors looped
through the clamps, but I can't immediately see an equivalent clause in
BS7671

--
Cheers,

John.

/================================================== ===============\
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| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 3 Jul, 20:12, John Rumm wrote:
SNIP

for is a connection to the water and gas mains in
most cases.

[1] The on site guide makes reference to "unbroken" conductors looped
through the clamps, but I can't immediately see an equivalent clause in
BS7671


I don't believe there is one. However C&G specify it as a fault for
visual identification in one of the practical tests for the 2391
Inspection, Test and Certification course.
A bit of "Gold Plating" has gone on I think.

John Rumm wrote:

[1] The on site guide makes reference to "unbroken" conductors looped
through the clamps, but I can't immediately see an equivalent clause in
BS7671

Try 528-02-06, bearing in mind that it's foreseeable that non-electrical
services could be moved or re-arranged.

--
Andy

John Rumm wrote:

413-02-02 In each installation main equipotential bonding conductors
complying with Section 547 shall connect to the main earthing terminal
extraneous-conductive-parts of that installation including the following:

(i) water service pipes
(ii) gas installation pipes
(iii) other service pipes and ducting
(iv) central heating and air conditioning systems
(v) exposed metallic structural parts of the building
(vi) the lightning protective system.

It's important to realise that the items in that list only have to be
main-bonded if they come within the definition of
extraneous-conductive-parts - i.e. if they are liable to import a
potential from outside the equipotential zone. A typical gas CH system
with all its pipework above ground level and not in a steel-framed
building will not usually require bonding. An oil-fired system with the
fuel feed pipe entering from underground should be bonded though.

--
Andy

I wrote:

Try 528-02-06

Oops, I meant 528-02-04. Incidentally, cable-tying bonding conductors
along gas and water pipes to keep them tidy is a deprecated practice, at
least according to NICEIC, by dint of the same regulation. Wiring
should not rely on the presence of any other service hardware for its
support.

--
Andy

Andy Wade wrote:
John Rumm wrote:

413-02-02 In each installation main equipotential bonding conductors
complying with Section 547 shall connect to the main earthing terminal
extraneous-conductive-parts of that installation including the following:

(i) water service pipes
(ii) gas installation pipes
(iii) other service pipes and ducting
(iv) central heating and air conditioning systems
(v) exposed metallic structural parts of the building
(vi) the lightning protective system.

It's important to realise that the items in that list only have to be
main-bonded if they come within the definition of
extraneous-conductive-parts - i.e. if they are liable to import a
potential from outside the equipotential zone. A typical gas CH system
with all its pipework above ground level and not in a steel-framed
building will not usually require bonding. An oil-fired system with the
fuel feed pipe entering from underground should be bonded though.

How does a oil system with feed entering from underground differ from a
gas one with gas coming via the same route?

--
Cheers,

John.

/================================================== ===============\
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| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Andy Wade wrote:

I wrote:

Try 528-02-06

That was almost a Rimmer Vs Kryten moment (for Red Dwarf fans!) ;-)

Oops, I meant 528-02-04.

That seems like a pretty tenuous link.... in so far as you could remove
a bonding clamp from a pipe without disconnecting its (potentially not
unbroken) wires. I take it there is a note in one of the "guidance to
the regs" type docs?

Incidentally, cable-tying bonding conductors
along gas and water pipes to keep them tidy is a deprecated practice, at
least according to NICEIC, by dint of the same regulation. Wiring
should not rely on the presence of any other service hardware for its
support.

That at least seems like a more logical deduction from the above
regulation.


--
Cheers,

John.

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|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:

Oops, I meant 528-02-04.

That seems like a pretty tenuous link.... in so far as you could remove
a bonding clamp from a pipe without disconnecting its (potentially not
unbroken) wires.

I think the idea is that a plumber (for example) can completely remove a
redundant clamp without affecting anything downstream and without the
need to re-make an electrical connection.

I take it there is a note in one of the "guidance to the regs" type
docs?

Pass - I don't have a full up-to-date set. I can't see any reference to
it as an inspection point in the current version of GN3, nor in an old
edition of GN1. It might be in the new GN8 on earthing and bonding, but
I'm waiting for the 17th edition version to appear before I buy that one.

See also the article on earthing and bonding in /Wiring Matters/ Issue
22 (page 13).

--
Andy

John Rumm wrote:

How does a oil system with feed entering from underground differ from a
gas one with gas coming via the same route?

Only insofar as the incoming gas service is a separate item on the list
in 413-02-02.

--
Andy

"John Rumm" wrote in message
...
Andy Wade wrote:
John Rumm wrote:

413-02-02 In each installation main equipotential bonding conductors
complying with Section 547 shall connect to the main earthing terminal
extraneous-conductive-parts of that installation including the
following:

(i) water service pipes
(ii) gas installation pipes
(iii) other service pipes and ducting
(iv) central heating and air conditioning systems
(v) exposed metallic structural parts of the building
(vi) the lightning protective system.

It's important to realise that the items in that list only have to be
main-bonded if they come within the definition of
extraneous-conductive-parts - i.e. if they are liable to import a
potential from outside the equipotential zone. A typical gas CH system
with all its pipework above ground level and not in a steel-framed
building will not usually require bonding. An oil-fired system with the
fuel feed pipe entering from underground should be bonded though.

How does a oil system with feed entering from underground differ from a
gas one with gas coming via the same route?

The gas pipe is bonded at the meter and many gas mains pipes are plastic.

"Andy Wade" wrote in message
...

A typical gas CH system with all its pipework above ground level and not
in a steel-framed building will not usually require bonding. An oil-fired
system with the fuel feed pipe entering from underground should be bonded
though.

Gas boilers in kitchens I see all the pipes under bonded and in some, and
not in others, the earth cable run back to the meter. Other boilers I see
not bonded at all.

It appears that this bonding is so confusing that Sparks just bond
everything in sight and run it back to the meter to be sure.

On 2007-07-04 02:01:55 +0100, Andy Wade said:

I wrote:

Try 528-02-06

Oops, I meant 528-02-04. Incidentally, cable-tying bonding conductors
along gas and water pipes to keep them tidy is a deprecated practice,
at least according to NICEIC, by dint of the same regulation. Wiring
should not rely on the presence of any other service hardware for its
support.

Slightly amusing since without the service pipe being there, there
wouldn't be a need for the bonding.

In article ews.net,
Doctor Drivel wrote:

"Andy Wade" wrote in message
...

A typical gas CH system with all its pipework above ground level and
not in a steel-framed building will not usually require bonding. An
oil-fired system with the fuel feed pipe entering from underground
should be bonded though.

Gas boilers in kitchens I see all the pipes under bonded and in some,
and not in others, the earth cable run back to the meter. Other
boilers I see not bonded at all.

It appears that this bonding is so confusing that Sparks just bond
everything in sight and run it back to the meter to be sure.

But you claim to be a heating engineer. Surely as such you'd have a grasp
of all pertinent regulations?

--
*Sorry, I don't date outside my species.

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

Andy Wade wrote:
John Rumm wrote:

How does a oil system with feed entering from underground differ from
a gas one with gas coming via the same route?

Only insofar as the incoming gas service is a separate item on the list
in 413-02-02.

Well that is kind of what I was getting at... it appeared that you were
singling out oil systems as needing bonding when the supply pipe comes
from underground, while at the same time saying that "A typical gas CH
system with all its pipework above ground level and not in a
steel-framed building will not usually require bonding" even though a
metallic supply pipe from underground is a common arrangement there also.

Part 413-02-02 (ii) will mean that most gas systems are by default
bonded if only at the gas pipe, allowing for the fact that most boilers
gas inlet will be made with a BSP taper thread connection and lots of
gas PTFE, so there is a chance that there will be electrical isolation
between gas pipe and boiler chassis.

--
Cheers,

John.

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

John Rumm wrote:

Well that is kind of what I was getting at... it appeared that you were
singling out oil systems as needing bonding when the supply pipe comes
from underground,

I was using the oil system as an example rather than singling it out,
but the said oil pipe is part of the heating system and if it
constitutes an ECP (extraneous-conductive-part) then it needs bonding to
satisfy 413-02-02 (iv).

Part 413-02-02 (ii) will mean that most gas systems are by default
bonded if only at the gas pipe, allowing for the fact that most boilers
gas inlet will be made with a BSP taper thread connection and lots of
gas PTFE, so there is a chance that there will be electrical isolation
between gas pipe and boiler chassis.

The point I was making here is that if the gas installation pipe is
bonded as an ECP under item (ii) then the remainder of the GCH system
will not need bonding under item (iv) unless it separately constitutes
an ECP, e.g. if there is heating pipework underground or in contact with
the ground. Whether or not there is electrical continuity through the
gas connection is irrelevant, so far as bonding is concerned. In
practice, regardless of main bonding, heating system pipework will
usually be _earthed_ via the CPCs of boiler, pump, valves, immersion
heater, etc. (and also via any bathroom supplementary bonding which ties
heating pipework to other CPCs).

Thinking about this more I guess external overflow, pressure relief or
condensate drain pipes from boilers could be ECPs in some cases, in
which case separate main bonding near the boiler is required.

--
Andy

Andy Hall wrote:

Slightly amusing since without the service pipe being there, there
wouldn't be a need for the bonding.

Quite, some common sense has to apply in the end. I think it's fair
game to secure bonding conductors to their associated pipes near to the
point of bonding, but fastening long runs of cable to pipes that just
happen to be handy at the time isn't good practice.

--
Andy

"Andy Wade" wrote in message
...
John Rumm wrote:

Well that is kind of what I was getting at... it appeared that you were
singling out oil systems as needing bonding when the supply pipe comes
from underground,

I was using the oil system as an example rather than singling it out, but
the said oil pipe is part of the heating system and if it constitutes an
ECP (extraneous-conductive-part) then it needs bonding to satisfy
413-02-02 (iv).

Part 413-02-02 (ii) will mean that most gas systems are by default bonded
if only at the gas pipe, allowing for the fact that most boilers gas
inlet will be made with a BSP taper thread connection and lots of gas
PTFE, so there is a chance that there will be electrical isolation
between gas pipe and boiler chassis.

The point I was making here is that if the gas installation pipe is bonded
as an ECP under item (ii) then the remainder of the GCH system will not
need bonding under item (iv) unless it separately constitutes an ECP, e.g.
if there is heating pipework underground or in contact with the ground.
Whether or not there is electrical continuity through the gas connection
is irrelevant, so far as bonding is concerned. In practice, regardless of
main bonding, heating system pipework will usually be _earthed_ via the
CPCs of boiler, pump, valves, immersion heater, etc. (and also via any
bathroom supplementary bonding which ties heating pipework to other CPCs).

Thinking about this more I guess external overflow, pressure relief or
condensate drain pipes from boilers could be ECPs in some cases, in which
case separate main bonding near the boiler is required.

--
Andy

The subject says a "guide". Is that so difficult? The lecky nerds here
should be able to give one. E.G.,

- typical semi or detached house
- gas CH with copper pipe
- hot and cold water in copper pipe
- boiler in kitchen
- elec meter near front door or under the stairs
- iron gas mains pipe
- metal water mains pipe
- normal shower in bathroom
- rad in bathroom

Now what needs to be done in that situation? Where will the earth cables
run to and from?

Exceptions:
- electric shower
- plastic mains gas pipe
- plastic CH pipe
- plastic hot and cold water pipe
- plastic water mains pipe
- any others people can think of

Andy Wade wrote:
Andy Hall wrote:

Slightly amusing since without the service pipe being there, there
wouldn't be a need for the bonding.

Quite, some common sense has to apply in the end. I think it's fair
game to secure bonding conductors to their associated pipes near to the
point of bonding, but fastening long runs of cable to pipes that just
happen to be handy at the time isn't good practice.

Especially as some pipes get hot. That can eat into your temperature
budget on the cable!

--
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 ews.net,
Doctor Drivel wrote:

"Andy Wade" wrote in message
...

A typical gas CH system with all its pipework above ground level and
not in a steel-framed building will not usually require bonding. An
oil-fired system with the fuel feed pipe entering from underground
should be bonded though.

Gas boilers in kitchens I see all the pipes under bonded and in some,
and not in others, the earth cable run back to the meter. Other
boilers I see not bonded at all.

It appears that this bonding is so confusing that Sparks just bond
everything in sight and run it back to the meter to be sure.

But

Please eff off as you are a worthless troll.

Andy Wade wrote:

Well that is kind of what I was getting at... it appeared that you
were singling out oil systems as needing bonding when the supply pipe
comes from underground,

I was using the oil system as an example rather than singling it out,

Ah, ok I see where you were going.

but the said oil pipe is part of the heating system and if it
constitutes an ECP (extraneous-conductive-part) then it needs bonding to
satisfy 413-02-02 (iv).

Part 413-02-02 (ii) will mean that most gas systems are by default
bonded if only at the gas pipe, allowing for the fact that most
boilers gas inlet will be made with a BSP taper thread connection and
lots of gas PTFE, so there is a chance that there will be electrical
isolation between gas pipe and boiler chassis.

The point I was making here is that if the gas installation pipe is
bonded as an ECP under item (ii) then the remainder of the GCH system
will not need bonding under item (iv) unless it separately constitutes
an ECP, e.g. if there is heating pipework underground or in contact with

Yup, that is fair enough...

the ground. Whether or not there is electrical continuity through the
gas connection is irrelevant, so far as bonding is concerned. In
practice, regardless of main bonding, heating system pipework will
usually be _earthed_ via the CPCs of boiler, pump, valves, immersion
heater, etc. (and also via any bathroom supplementary bonding which ties
heating pipework to other CPCs).

Thinking about this more I guess external overflow, pressure relief or
condensate drain pipes from boilers could be ECPs in some cases, in
which case separate main bonding near the boiler is required.

Overflows and condensate drains are usually run in plastic, and the
pressure relief will not usually make contact with ground, so this ought
not be a problem in most cases.


--
Cheers,

John.

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

On Wed, 04 Jul 2007 15:11:49 +0100, John Rumm
wrote:

Andy Wade wrote:
Andy Hall wrote:

Slightly amusing since without the service pipe being there, there
wouldn't be a need for the bonding.

Quite, some common sense has to apply in the end. I think it's fair
game to secure bonding conductors to their associated pipes near to the
point of bonding, but fastening long runs of cable to pipes that just
happen to be handy at the time isn't good practice.

Especially as some pipes get hot. That can eat into your temperature
budget on the cable!

But it could work the other way, if it's a cold water pipe!

:-)
--
Frank Erskine

Frank Erskine wrote:
On Wed, 04 Jul 2007 15:11:49 +0100, John Rumm
wrote:

Andy Wade wrote:
Andy Hall wrote:

Slightly amusing since without the service pipe being there, there
wouldn't be a need for the bonding.
Quite, some common sense has to apply in the end. I think it's fair
game to secure bonding conductors to their associated pipes near to the
point of bonding, but fastening long runs of cable to pipes that just
happen to be handy at the time isn't good practice.
Especially as some pipes get hot. That can eat into your temperature
budget on the cable!

But it could work the other way, if it's a cold water pipe!

I would love to see the discussion for that one! "Yup, I have rated this
2.5mm^2 T&E at 45A continuous, but it is ok because this is based on an
average flow rate of 25 litres per min of water not exceeding 25 degrees
through the cold pipe that it is bonded to with cable ties and
thermopath grease!"

--
Cheers,

John.

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

On Wed, 04 Jul 2007 16:03:52 +0100, John Rumm wrote:

Frank Erskine wrote:
On Wed, 04 Jul 2007 15:11:49 +0100, John Rumm
wrote:

Andy Wade wrote:
Andy Hall wrote:

Slightly amusing since without the service pipe being there, there
wouldn't be a need for the bonding.
Quite, some common sense has to apply in the end. I think it's fair
game to secure bonding conductors to their associated pipes near to the
point of bonding, but fastening long runs of cable to pipes that just
happen to be handy at the time isn't good practice.
Especially as some pipes get hot. That can eat into your temperature
budget on the cable!

But it could work the other way, if it's a cold water pipe!

I would love to see the discussion for that one! "Yup, I have rated this
2.5mm^2 T&E at 45A continuous, but it is ok because this is based on an
average flow rate of 25 litres per min of water not exceeding 25 degrees
through the cold pipe that it is bonded to with cable ties and
thermopath grease!"

Nice one!
The trouble is that at some point the shower feed must leave the cold pipe
and go to the CU. You can't get around it by upping the cable size for the
last section because of the reg (473-01-01) that states you have to have
protective gear where the CSA changes. 8-(




--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Wed, 04 Jul 2007 13:31:01 +0100, Andy Wade wrote:

John Rumm wrote:

Well that is kind of what I was getting at... it appeared that you were
singling out oil systems as needing bonding when the supply pipe comes
from underground,

I was using the oil system as an example rather than singling it out,
but the said oil pipe is part of the heating system and if it
constitutes an ECP (extraneous-conductive-part) then it needs bonding to
satisfy 413-02-02 (iv).

Part 413-02-02 (ii) will mean that most gas systems are by default
bonded if only at the gas pipe, allowing for the fact that most boilers
gas inlet will be made with a BSP taper thread connection and lots of
gas PTFE, so there is a chance that there will be electrical isolation
between gas pipe and boiler chassis.

The point I was making here is that if the gas installation pipe is
bonded as an ECP under item (ii) then the remainder of the GCH system
will not need bonding under item (iv) unless it separately constitutes
an ECP, e.g. if there is heating pipework underground or in contact with
the ground. Whether or not there is electrical continuity through the
gas connection is irrelevant, so far as bonding is concerned. In
practice, regardless of main bonding, heating system pipework will
usually be _earthed_ via the CPCs of boiler, pump, valves, immersion
heater, etc. (and also via any bathroom supplementary bonding which ties
heating pipework to other CPCs).

Thinking about this more I guess external overflow, pressure relief or
condensate drain pipes from boilers could be ECPs in some cases, in
which case separate main bonding near the boiler is required.

I find in practice GCH is never explicitly bonded even when a portion is
set in the ground floor screed.

However quite often the GCH is supplementary bonded regardless of the
location of the boiler. The gas installation pipework is always in
practice an excellent earth, although in principle you could have joints
that were not good electrical connections due to Boss/Hawk White or the
gas grade PTFE.

In practice gas fitters usually bond all the pipes at the boiler
regardless of the necessity.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

Ed Sirett wrote:
On Wed, 04 Jul 2007 16:03:52 +0100, John Rumm wrote:

Frank Erskine wrote:
On Wed, 04 Jul 2007 15:11:49 +0100, John Rumm
wrote:

Andy Wade wrote:
Andy Hall wrote:

Slightly amusing since without the service pipe being there, there
wouldn't be a need for the bonding.
Quite, some common sense has to apply in the end. I think it's fair
game to secure bonding conductors to their associated pipes near to the
point of bonding, but fastening long runs of cable to pipes that just
happen to be handy at the time isn't good practice.
Especially as some pipes get hot. That can eat into your temperature
budget on the cable!
But it could work the other way, if it's a cold water pipe!
I would love to see the discussion for that one! "Yup, I have rated this
2.5mm^2 T&E at 45A continuous, but it is ok because this is based on an
average flow rate of 25 litres per min of water not exceeding 25 degrees
through the cold pipe that it is bonded to with cable ties and
thermopath grease!"

Nice one!
The trouble is that at some point the shower feed must leave the cold pipe
and go to the CU. You can't get around it by upping the cable size for the
last section because of the reg (473-01-01) that states you have to have
protective gear where the CSA changes. 8-(

You can do without the protective device at the change if the head end
device is sized to protect the smaller of the two cables though (i.e.
the water cooled one!). Either that or you need to plumb in the CU as
well ;-)


--
Cheers,

John.

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

Ed Sirett wrote:

I find in practice GCH is never explicitly bonded even when a portion is
set in the ground floor screed.

Pipes in a screed should of course be thermally insulated and/or ducted
or wrapped etc., and aren't too likely to be in good electrical contact
with the surrounding screed. In any case the screed should be fairly
dry. The resistance to the general mass of earth is likely to be too
high to deliver a dangerous shock current, however high the touch
voltage to the local earthing and bonding, so I can't see to much of a
case to be made for explicit main bonding in these circumstances.

In practice gas fitters usually bond all the pipes at the boiler
regardless of the necessity.

Yes, it's always puzzled me why they do that. (Unless the boiler's in a
bath or shower room, of course, but the wisdom of doing that could open
another can of worms...) You often see it in airing cupboards too.

--
Andy

Ed Sirett wrote:

Nice one!
The trouble is that at some point the shower feed must leave the cold pipe
and go to the CU.

Easily solved: just route the incoming CW main via the CU enclosure!
This will be handy for doing the main water bond too - you could solder
the main earth bar straight onto the water pipe.

--
Andy

"Andy Wade" wrote in message
...
Ed Sirett wrote:

I find in practice GCH is never explicitly bonded even when a portion is
set in the ground floor screed.

Pipes in a screed should of course be thermally insulated and/or ducted or
wrapped etc., and aren't too likely to be in good electrical contact with
the surrounding screed. In any case the screed should be fairly dry. The
resistance to the general mass of earth is likely to be too high to
deliver a dangerous shock current, however high the touch voltage to the
local earthing and bonding, so I can't see to much of a case to be made
for explicit main bonding in these circumstances.

In practice gas fitters usually bond all the pipes at the boiler
regardless of the necessity.

Yes, it's always puzzled me why they do that. (Unless the boiler's in a
bath or shower room, of course, but the wisdom of doing that could open
another can of worms...) You often see it in airing cupboards too.

They do it because even electricians don't understand bonding, so they do
all in sight.

On Thu, 05 Jul 2007 12:28:33 +0100, Andy Wade wrote:

Ed Sirett wrote:

I find in practice GCH is never explicitly bonded even when a portion is
set in the ground floor screed.

Pipes in a screed should of course be thermally insulated and/or ducted
or wrapped etc., and aren't too likely to be in good electrical contact
with the surrounding screed. In any case the screed should be fairly
dry. The resistance to the general mass of earth is likely to be too
high to deliver a dangerous shock current, however high the touch
voltage to the local earthing and bonding, so I can't see to much of a
case to be made for explicit main bonding in these circumstances.

In practice gas fitters usually bond all the pipes at the boiler
regardless of the necessity.

Yes, it's always puzzled me why they do that. (Unless the boiler's in a
bath or shower room, of course, but the wisdom of doing that could open
another can of worms...) You often see it in airing cupboards too.

Try arguing with the CORGI inspector who takes a simplistic view of the
regs...





--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards