Is there a good book explaining all the niggly things regarding 17th
edition wiring, like a wiring "bible"?
This is so I know the "standard" ways of doing things, which always
helps, and stops me asking a million and one small questions on the
group.
I have on onsite guide already.
I will give the wiki a good read.

What I was wondering presently whilst considering the wiring
requirements:

1. What is the usual way to run cables around a room with a solid
floor ? In this case it is a kitchen and most of the sockets will be
just above work surface height, plus a couple of armoured cable
lengths (freezer, exterior wiring). Running inside the ceiling void
and down behind cabinets to everything would not seem like a good
solution.
Note: between the CU and kitchen will be a small downstairs toilet, so
running all the wiring at socket level would be a problem at this
area, as would running everything visible, such as inside kitchen
units.

2. If a cable is run though the centre of 9" floor joists, is it
considered "buried", i.e. RCD not required ? Obviously at some point
it will leave this "buried" area, but you could junction to a
different type of cable at this point.

3. If an armoured cable is used (non-RCD freezer or cable for external
wiring), can it be hidden anywhere, or does it still have to be in a
safe zone (corners, in line with visible fittings etc) ?

4. Is it true that all visible wiring must be in trunking, even right
next to the CU ? What about the need to retro-fit such trunking to all
existing cables for circuits that are not being touched ?

I would imagine any such wiring "bible" would include these sort of
issues.
Cheers,
Simon.

sm_jamieson
wibbled on Saturday 17 July 2010 10:10

Is there a good book explaining all the niggly things regarding 17th
edition wiring, like a wiring "bible"?

The OnSite Guide would be a good starting point. There are many other
explanatory guides including various NICEIC publications.

This is so I know the "standard" ways of doing things, which always
helps, and stops me asking a million and one small questions on the
group.
I have on onsite guide already.
I will give the wiki a good read.

What I was wondering presently whilst considering the wiring
requirements:

1. What is the usual way to run cables around a room with a solid
floor ?

Horizontally or ceiling drops depending on what's most convenient.

In this case it is a kitchen and most of the sockets will be
just above work surface height, plus a couple of armoured cable
lengths (freezer, exterior wiring). Running inside the ceiling void
and down behind cabinets to everything would not seem like a good
solution.

It's the way I've done it. One drop at each end of a run of sockets,
horizontally between.

Note: between the CU and kitchen will be a small downstairs toilet, so
running all the wiring at socket level would be a problem at this
area, as would running everything visible, such as inside kitchen
units.

2. If a cable is run though the centre of 9" floor joists, is it
considered "buried", i.e. RCD not required

Yes. 50mm is the rule where applicable.


? Obviously at some point
it will leave this "buried" area, but you could junction to a
different type of cable at this point.

3. If an armoured cable is used (non-RCD freezer or cable for external
wiring), can it be hidden anywhere, or does it still have to be in a
safe zone (corners, in line with visible fittings etc) ?

You can do what you like with SWA, MICC or foil shielded. BTW have you
considered the XL-Shield class of cables as an alternative? Another approach
would be to drop T+E in some surface microtrunking - then it is deemed
visble and does not require RCD protection.

BTW - are you really paranoid about not having an RCD on the freezer
circuit? The number of times I've had a spurious trip since 1995 is zero,
though I realise some people may have been unlucky.

4. Is it true that all visible wiring must be in trunking,

No. Where did you get that idea? Visible cables are quite common, especially
under the stairs on older houses.

even right
next to the CU ? What about the need to retro-fit such trunking to all
existing cables for circuits that are not being touched ?


I would imagine any such wiring "bible" would include these sort of
issues.
Cheers,
Simon.

--
Tim Watts

Managers, politicians and environmentalists: Nature's carbon buffer.

On 17 July, 10:24, Tim Watts wrote:
sm_jamieson
* wibbled on Saturday 17 July 2010 10:10

Is there a good book explaining all the niggly things regarding 17th
edition wiring, like a wiring "bible"?

The OnSite Guide would be a good starting point. There are many other
explanatory guides including various NICEIC publications.

This is so I know the "standard" ways of doing things, which always
helps, and stops me asking a million and one small questions on the
group.
I have on onsite guide already.
I will give the wiki a good read.

What I was wondering presently whilst considering the wiring
requirements:

1. What is the usual way to run cables around a room with a solid
floor ?

Horizontally or ceiling drops depending on what's most convenient.

In this case it is a kitchen and most of the sockets will be
just above work surface height, plus a couple of armoured cable
lengths (freezer, exterior wiring). Running inside the ceiling void
and down behind cabinets to everything would not seem like a good
solution.

It's the way I've done it. One drop at each end of a run of sockets,
horizontally between.

Yep, thats the way I'll do it.


Note: between the CU and kitchen will be a small downstairs toilet, so
running all the wiring at socket level would be a problem at this
area, as would running everything visible, such as inside kitchen
units.

2. If a cable is run though the centre of 9" floor joists, is it
considered "buried", i.e. RCD not required

Yes. 50mm is the rule where applicable.

? Obviously at some point
it will leave this "buried" area, but you could junction to a
different type of cable at this point.

3. If an armoured cable is used (non-RCD freezer or cable for external
wiring), can it be hidden anywhere, or does it still have to be in a
safe zone (corners, in line with visible fittings etc) ?

You can do what you like with SWA, MICC or foil shielded. BTW have you
considered the XL-Shield class of cables as an alternative? Another approach
would be to drop T+E in some surface microtrunking - then it is deemed
visble and does not require RCD protection.

XL-shield If thats a cheaper alternative good.
Not much came up on web search - only farnell.


BTW - are you really paranoid about not having an RCD on the freezer
circuit? The number of times I've had a spurious trip since 1995 is zero,
though I realise some people may have been unlucky.

4. Is it true that all visible wiring must be in trunking,

No. Where did you get that idea? Visible cables are quite common, especially
under the stairs on older houses.

Indeed. Its something I heard somewhere ! I'm glad its not true -
seemed a bit ridiculous.


even right
next to the CU ? What about the need to retro-fit such trunking to all
existing cables for circuits that are not being touched ?
I would imagine any such wiring "bible" would include these sort of
issues.
Cheers,
Simon.

--
Tim Watts


Thanks,
Simon.

"sm_jamieson" wrote in message
...
Is there a good book explaining all the niggly things regarding 17th
edition wiring, like a wiring "bible"?
This is so I know the "standard" ways of doing things, which always
helps, and stops me asking a million and one small questions on the
group.
I have on onsite guide already.
I will give the wiki a good read.

http://www.amazon.co.uk/Electricians-Guide-Wiring-Regulations-Building/dp/0953788555
is worth a read.

and

http://www.voltimum.co.uk/

and type a search term in at the top should help with some of your
questions.

What I was wondering presently whilst considering the wiring
requirements:

1. What is the usual way to run cables around a room with a solid
floor ? In this case it is a kitchen and most of the sockets will be
just above work surface height, plus a couple of armoured cable
lengths (freezer, exterior wiring). Running inside the ceiling void
and down behind cabinets to everything would not seem like a good
solution.
Note: between the CU and kitchen will be a small downstairs toilet, so
running all the wiring at socket level would be a problem at this
area, as would running everything visible, such as inside kitchen
units.

Horizontal between the sockets is fine.
Also clipping to the skirting or wall behind the cupboards is fine. I often
do this where the cable run goes past the kitchen window and it also then
supplies the sockets in the cupboards for the washer/dishwasher which are
usually under the window by the sink.

2. If a cable is run though the centre of 9" floor joists, is it
considered "buried", i.e. RCD not required ? Obviously at some point
it will leave this "buried" area, but you could junction to a
different type of cable at this point.

A cable through the centre of the joists would not need RCD protection.

3. If an armoured cable is used (non-RCD freezer or cable for external
wiring), can it be hidden anywhere, or does it still have to be in a
safe zone (corners, in line with visible fittings etc) ?

Pg 60 of your OSG is your friend. It is not something I would consider
doing. A nail will penetrate armoured easliy enough and then you have to
start repairing it.

It might be as easy and as cheap to give the fridge it's own RCBO and just
use T&E. That way there is no messing about with glands etc.


4. Is it true that all visible wiring must be in trunking, even right
next to the CU ? What about the need to retro-fit such trunking to all
existing cables for circuits that are not being touched ?

Not true.
If you wanted to, you could surface mount all your cables (subject to impact
assesment) and not use any trunking. The wife would love that:-)

HTH

Adam

On Jul 17, 10:10*am, sm_jamieson wrote:
1. What is the usual way to run cables around a room with a solid
floor ?

Flat ceiling:
150mm ceiling zone with vertical drops from it to sockets.
150mm corner zone to get the cables up there in the first place.

Sloping ceiling, espec. wet verge with sharp trowels every 10yrs:
a) Horizontal ceiling zone created by a 1G or 2G box with blankplate
on wall. Vertical drops to sockets from that zone.
b) Horizontal skirting zone created by a 1G or 2G box with blankplate
on wall. Vertical rises to sockets from that zone.

Sit down and draw out several solutions, then choose between them.
Nothing worse than regrets.


3. If an armoured cable is used (non-RCD freezer or cable for external
wiring), can it be hidden anywhere, or does it still have to be in a
safe zone (corners, in line with visible fittings etc) ?

As a point of note, SWA requires glands to be accessible for
inspection & testing. You would now use BS8436 which is far simpler,
neater & quicker, no glands required.

BS8436 is hard to source (TLC will not carry it after contacting
NICEIC) because it imposes *critical* restrictions on the type of
circuit breaker (type-b) & rating (32A max for 2.5mm ring, 20A max for
2.5mm radial) that it may be used with. This is because the cable's
earthed foil surround can only withstand a certain amount of let-
through current (I^2t) before it gets vapourised before a fault can be
disconnected.
You can buy BS8436 in cut lengths from www.discount-electrical.co.uk
(not on their website) under Prysmian Earthshield or Guardian brands
or Nexans NXS. It occasionally crops up on Ebay. Prysmian have a new
version for the revised BS8436 due in 2011/2012. Guardian is commonly
available in white and black which can be useful.

Frankly I would RCD it, if you want no nuisance tripping use a 16-20A
RCBO with dedicated radial.


4. Is it true that all visible wiring must be in trunking, even right
next to the CU ? What about the need to retro-fit such trunking to all
existing cables for circuits that are not being touched ?

Where does this trunking view come from?

Under 16th 522-06-02 (17th has similar):
"in a fixed installation where an impact of Medium Severity (AG2) or
Higher Severity (AG3) can occur protection shall be afforded by:
i) The mechanical characteristics of the wiring system, or
ii) The location Selected, or
iii) The provision of additional local or general mechanical
protection or by any combination of the above.

Domestic environment is defined as Low severity from impact (AG1).
Flat Twin & Earth has Medium impact severity (AG2).
Therefore no trunking is required.

You may want to add trunking if you run a cable where it becomes
target #1 from impact with appliances (surface run on the face of
skirting would be dumb where furniture can hit it, but not if run
above skirting). Likewise trunking comes in many flavours, in some
situations D-line looks ok, the larger sizes can look fugly though -
like 1.2m sockets every 6ft around a room above appliances, tables,
TV :-)

Wiring regulations are not retrospective incidentally except.
1 - MEB must be correct, ESC website has interesting comments re 6mm
incidentally.
2 - if you extend a f.c. that lacks RCD protection you need to add RCD
protection - most use a RCD fused spur, personally I would use a 20A
RCD at the CU end in the cupboard with surface or BS8436 w/20A MCB
breaking the cable so the whole circuit has it.

If you have a dedicated CU cupboard you certainly do not need to run
trunking all around it, more often than not you end up breaking bend
radius limits and grouping factors. It is a myth because trunking is
the most effective way of working up the hours known to man short of
digging a hole and staring down it for half a day, ok that and fitting
a fish-switch at a central location for every single EmLight in an
entire building.


On Site Guide, Electrician's guide to BR, John Whitfield guide
although he likes bonding kitchen sinks although there is no reason -
the whole bonding nonsense got out of control with even an IEE article
(or two) on it. 17th makes things more realistic and frankly "Class-II
everything" in a bathroom someday would be a good idea. A lot of loop-
in supplies out there, shared water mains, and lots of peculiar things
can happen with faults far away from you. Undo the MEB at one end of a
terrace (without bridging cable in place) and you become the conductor
if there is a fault at the other end; it happens.

"js.b1" wrote in message
...


BS8436 is hard to source (TLC will not carry it after contacting
NICEIC) because it imposes *critical* restrictions on the type of
circuit breaker (type-b) & rating (32A max for 2.5mm ring, 20A max for
2.5mm radial) that it may be used with. This is because the cable's
earthed foil surround can only withstand a certain amount of let-
through current (I^2t) before it gets vapourised before a fault can be
disconnected.
You can buy BS8436 in cut lengths from www.discount-electrical.co.uk
(not on their website) under Prysmian Earthshield or Guardian brands
or Nexans NXS. It occasionally crops up on Ebay. Prysmian have a new
version for the revised BS8436 due in 2011/2012. Guardian is commonly
available in white and black which can be useful.

What have you paid for the 2.5mm BS8436 cable? I have not used it yet and I
am interested in what it costs (google is not my friend on this)

Cheers

Adam

On Jul 17, 1:50*pm, "ARWadsworth"
wrote:
What have you paid for the 2.5mm BS8436 cable? I have not used it yet and I
am interested in what it costs (google is not my friend on this)

It is priced like armoured...

Discount Electrical:
- Cut length - Prysmian BS8436 Earthshield 2.5mm for about £1.21/m
- Reel - about £100-120 per 100m

RS Components:
- Reel - about £162 for 100m, Farnell did Nexans NXS at one point.

Ebay:
- Reel - about £25-50-(80) delivered, reels are heavy wood/plastic
- Cut length - about £10-20 for 20-50m when available

Major names are...
- Guardian Cable -- Batt Cables? Cleveland Cables?
- Prysmian Flexishield
- Prysmian Earthshield
- Nexans NXS

An FP cable can not comply with BS8436 because an FP cable requires FP
sheath whereas the actual BS8436 standard specifies the sheath be GP8.
Therefore marketing may say their FP cable complies with the BS8436
nail test, but the sheath material will not comply with BS8436.
Someone might want to telephone Prysmian engineering who have just
submitted an updated BS8436 standard to see if it still specifies GP8
sheath (I guess it might :-)

What is it like to handle.
Prysmian Earthshield BS8436 2.5mm - chunky, stiff (holds shape re
dressing), large bend radius or it crushes, XLPE insulation. Guardian
BS8436 1.5mm - same, wood reel weight similar to 4mm FTE. Almost
certain it is XLPE insulation.

I have not used any, just "on the shelf" if needed. The 1.5mm black
will get used for an outside light with RCD protection in place of
1-1.5mm H07RNF flex (for added safety) and for a tortuous route to a
ceiling rose with RCD protection that would otherwise require removal
of a wall that was added.

The problem for marketing is most people can design out the need for
it. It is good commercially for freezers where you may not want RCD
protection (or cheaper than RCBO to individual freezers in a retail
outlet). It is good commercially for labs where you may want
individual RCD protected sockets in a lab, not RCD protected at the
head end. Hospitals probably like it compared to SWA re making-off
time. In a domestic environment it might help with the odd light drop
or socket run in convoluted timber construction. I see a problem with
economy of scale, although the industry desire to move from PVC to
XLPE will narrow prices a little.

Error - "FP insulation" in place of "FP sheath" & "GP8 insulation" in
place of "GP8 sheath".

"js.b1" wrote in message
...
On Jul 17, 1:50 pm, "ARWadsworth"
wrote:
What have you paid for the 2.5mm BS8436 cable? I have not used it yet and
I
am interested in what it costs (google is not my friend on this)

It is priced like armoured...

Discount Electrical:
- Cut length - Prysmian BS8436 Earthshield 2.5mm for about £1.21/m
- Reel - about £100-120 per 100m

RS Components:
- Reel - about £162 for 100m, Farnell did Nexans NXS at one point.

Ebay:
- Reel - about £25-50-(80) delivered, reels are heavy wood/plastic
- Cut length - about £10-20 for 20-50m when available

Major names are...
- Guardian Cable -- Batt Cables? Cleveland Cables?
- Prysmian Flexishield
- Prysmian Earthshield
- Nexans NXS

An FP cable can not comply with BS8436 because an FP cable requires FP
sheath whereas the actual BS8436 standard specifies the sheath be GP8.
Therefore marketing may say their FP cable complies with the BS8436
nail test, but the sheath material will not comply with BS8436.
Someone might want to telephone Prysmian engineering who have just
submitted an updated BS8436 standard to see if it still specifies GP8
sheath (I guess it might :-)

What is it like to handle.
Prysmian Earthshield BS8436 2.5mm - chunky, stiff (holds shape re
dressing), large bend radius or it crushes, XLPE insulation. Guardian
BS8436 1.5mm - same, wood reel weight similar to 4mm FTE. Almost
certain it is XLPE insulation.

I have not used any, just "on the shelf" if needed. The 1.5mm black
will get used for an outside light with RCD protection in place of
1-1.5mm H07RNF flex (for added safety) and for a tortuous route to a
ceiling rose with RCD protection that would otherwise require removal
of a wall that was added.

The problem for marketing is most people can design out the need for
it. It is good commercially for freezers where you may not want RCD
protection (or cheaper than RCBO to individual freezers in a retail
outlet). It is good commercially for labs where you may want
individual RCD protected sockets in a lab, not RCD protected at the
head end. Hospitals probably like it compared to SWA re making-off
time. In a domestic environment it might help with the odd light drop
or socket run in convoluted timber construction. I see a problem with
economy of scale, although the industry desire to move from PVC to
XLPE will narrow prices a little.

Thanks for that.

I will price some up from my wholesalers when I am next there and see how it
compares. It could be handy in some installs.

Cheers

Adam

On 17/07/10 16:08, John Rumm wrote:
I usually drop down from the ceiling to the first socket in a row, and
then horizontally between them and back to the ceiling to dodge doorways
etc.

I've just been doing exactly that over the weekend for our downstairs
ring mains - solid floor so it all goes up into the suspended floor
upstairs.

The only trouble is that you use an awful lot of cable if as in our
house your windows come down to below the 450mm socket height,
especially if you are strict about the guidelines for drilling joist
holes between 0.25 and 0.4 of the joist span.

For instance, in our 7m x 4m lounge which is 2.5m high, between each
socket uses 9 or 10m of cable. This meant I ended up with 2 ring mains
downstairs to fit within the cable length limits. This all adds up in
terms of T+E, extra RCBOs & time required to cap the extra cable.

Just the lighting to finish off, the smoke alarms, burglar alarm, cat 6
install and central heating to go before plasterboard can be tacked...

"Jim" wrote in message
...
On 17/07/10 16:08, John Rumm wrote:
I usually drop down from the ceiling to the first socket in a row, and
then horizontally between them and back to the ceiling to dodge doorways
etc.

I've just been doing exactly that over the weekend for our downstairs ring
mains - solid floor so it all goes up into the suspended floor upstairs.

The only trouble is that you use an awful lot of cable if as in our house
your windows come down to below the 450mm socket height, especially if you
are strict about the guidelines for drilling joist holes between 0.25 and
0.4 of the joist span.

For instance, in our 7m x 4m lounge which is 2.5m high, between each
socket uses 9 or 10m of cable. This meant I ended up with 2 ring mains
downstairs to fit within the cable length limits. This all adds up in
terms of T+E, extra RCBOs & time required to cap the extra cable.

I often do not install the traditional upstairs/downstairs rings for exactly
that reason.
A left/right split on a house is often cheaper, easier and better for
voltage drop.


Just the lighting to finish off, the smoke alarms, burglar alarm, cat 6
install and central heating to go before plasterboard can be tacked...

So you should be done for 4pm then:-)?

Cheers

Adam

On 19/07/10 12:38, ARWadsworth wrote:
For instance, in our 7m x 4m lounge which is 2.5m high, between each
socket uses 9 or 10m of cable. This meant I ended up with 2 ring mains
downstairs to fit within the cable length limits. This all adds up in
terms of T+E, extra RCBOs& time required to cap the extra cable.

I often do not install the traditional upstairs/downstairs rings for exactly
that reason.
A left/right split on a house is often cheaper, easier and better for
voltage drop.

That would have actually made a lot of sense and saved a lot of cable -
oh well!

Just the lighting to finish off, the smoke alarms, burglar alarm, cat 6
install and central heating to go before plasterboard can be tacked...

So you should be done for 4pm then:-)?

Fortunately it's all just first fix, so should be done in fairly short
order.