Just eyeballing 3000, s3.9.4.5, regarding "safe" locations of wiring in walls. What constitutes free movement of a cable?

I assume the intent is to allow anything penetrating the wall to deflect the cable instead of cutting it, not many contractors i know that leave that much slack in wiring, or hole saws/spade bits that are designed with deflection guards.

Anyone seen a ruling on this one?

Hi Spock,
For those "not in the know" about this bit of legislation:

One thing that annoys me these days, is the fact that timber in houses is so much thinner than what it was when I started my time as an Electrician.
It was all rough sawn 100 x 50 mm,
these days it's all been watered down to Kiln- dried ex 85x40.
It might be better for the builders to work with.
But I digress, no good in a decent earthquake though.

Gentlemen, we in the UK have a simular regulation 522-06-06, this calls for the use of earthed metal conduit to protect cables run in a wall or partition of less than 50mm in depth from the cable to any surface of the wall or partition.
An alternative offered in our regs is to run cables in what are termed permitted zones.That is vertically from above or bellow any outlet or accessory. Horizontally from accessories, 150mm horizontally from the ceiling and in any corner of a room vertically upto 150mm from the corner.
If the zone route is chosed it must be clearly identifiable from both sides of the wall. Probably best option is the steel conduit.
Agree with you Mike walls have become painfully thin over the last few years.

So painfully thin that when my oldest sprog put 4 of those big-screw self-drilling rockwall fixings in his bedroom wall to support the tv bracket, they emerged on the other side into the stairwell! Length 1.5". The "Wall" turned out to be two sheets of 1/2" sheetrock, back-to-back, no studs! That's in a brand new US $400,000 dollar house!
Nationally known UK builder.


Alan

Alan is this "WALL" supposed to be supporting anything ?

Surely a nationally known building company wouldn't build a supportive wall without framing ?

Would they ?

Kiwi,
As is usual in the UK, the external walls consist of 4" of brick, with an 8" lightweight (foamed) cement inner wall tied every 3ft horiz. and 18" vert. to each other with metal-ties bedded in the mortar and spanning the cavity, which can have an insulation board fitted within. A further rockwall skin inside may also be insulated. This traditional 'cavity-wall' has been proved to resist water penetration from the bit of rain we get occasionally in England. The roof structure is spanned over the masonary walls with trussed rafters, such that all the roof loads, tile, man-access, snow, wind etc., bear to the brickwork skin only. This means that all the internal room-dividing walls are non-loadbearing. Then, at the stairwell, where it abuts to bedrooms, the "wall" can be of enough sheetrock thickness to comply with the UK Building Regulations, which of course at this location is only the strength of a standard stairway handrail! There is a genuine need to cut build costs in the UK, where houses are so expensive due to a shortage of building land. That $400,000 house by the way is an ordinary 4 bed 'box' on an estate, 150 miles from London, nowt fancy, but my boy will be paying around 40% of his take home pay in mortgage payments for the next twenty five years provided interest rates stay low. If they rise to 1980s levels, he'll be ruined or on the cadge to me!

Alan

Real estate prices are just insane in Britain these days. Take a look here for an idea of what's on offer:
http://www.rightmove.co.uk/


Multiply Sterling prices by:

1.8 to get U.S. dollars
2.4 for Australian dollars
2.6 for New Zealand dollars

Alors! - Raisons que des Anglais ont achetées ses maisons ici en France:
Maisons tres moins cher ici.
Taxes sur salaire ou pensions aussi tres moins cher ici.
Systeme medicale, le premiere qualité du monde.
Du vin!
Du soleil!
Pas de crime ou drugs ( en campagne).
Pas de "road tax".
Et, pas de Tony!!!

Alan

You rang, Mr. Belson?

Tony

Paul, our house has a rather different set up to that.

The external walls are concrete block which is plastered and painted.

There is then a layer of foam insulation, then the cavity then another layer of blocks that form the internal walls. They are battoned and covered with fiberglass insulation then a moisture membrane then plasterboard which is skimmed with plaster and painted.

The internal walls are solid block construction which is then plastered. The electrical fittings and cables are, for the most part, burried in this plaster (in conduit)

The floors are concrete with a fine screde on top. (there's a layer of insulation and damn proofing obviously too)

The heating pipes (pair of copper pipes) that feed the radiators are burried in thick insulation in the concrete.

We also have some runs of cable burried in the floors feeding outlets in hallways.

This is then all covered by a "floating" wooden (ash) floor which sits on a layer of foam insulation to reduce noise and to provide some extra thermal insulation.

(Tiles in the bathrooms)

Upstairs is all solid hardwood flooring (the main living area)

The house is build on a slope so is split level with the bedrooms on the lower level and the living area on the upper level to maximise the view.

There's also a narrow basement area that runs the length of the house and carries most of the wiring and plumbing.

All the wiring is radial & is fed from a 4 row Hager distribution board (consumer unit)

And I thought prices in California were insane.. (median price here is $489,000.00US)

djk:

From your description, it would seem that your home is highly energy efficient.

I'm curious, in construction as yours, how does one do additions/remodels? It would seem to require major plaster work....

Tony,
Ireland is even wetter than England and Wales, and I noted from djk's post that a cavity is also installed between the masonry leaves. For additions you have to disc-cut/break through an access doorway and seal the cavity off with bricks/blocks and a damp membrane, then tie the new/old structures together. This is done by either keying the bricks in at the join ( interlocked and retains a cavity), or by bolting a vertical steel plate to the old abutting wall and using clip-in ties at each course ( new cavity, not connected). Getting bricks to match is a nightmare, as there are literally hundreds of facing-brick types/colors, and of course discontinued lines! Blockwork is easier, as the outer elevations will usually be cement rendered.
For re-modelling, yes it's a lot of mess & dust but folks do it, replastering over new/old masonry with mortar scratchcoats and finish plaster. This type of work is usually where two small rooms are knocked into one, with a steel joist inserted if the wall was load bearing. The wiring, as in Ireland, is usually chased into the wallwork, and you can even get a cutter which drills square holes for the boxes!

Alan

The other way and most common way to be exempt from this rule is to have the cable RCD protected. My understanding is that it is not compulsory to have RCD protection but imposible to comply with the first said rule AS3000 s3.9.4.5 without it as you were correct the internal walls are too narrow and you cannot gaurantee where the cable you dropped down the wall will hang especially if its insulated.

Alan:

A tip of the hat and a large mug of finest to your sir, thanks for the great explanation!

A cutter that does square holes? Wow! Do you have a picture or link to that beast?

Cheers!

A cutter that does square holes?

Would that be called a chasing chisel!
Only joking try www.armeg.co.uk. I have one of these they are OK as long as the bricks are not too hard. Dusty old thing to use as well!Does a job though. Regards Aland

Welcome to the group Mash!.
However,
Using an RCD as a be all and end all to all of the problems associated with Electricity is wrong.
Good circuit design and installation come into it too.
Oh and BTW Alan, we use a Hyrdaulic cutter to cut out our 72 x 72mm or 96 x 96mm meters in our panels.

[This message has been edited by Trumpy (edited 09-24-2005).]

I could not agree more about correct installation and design. It would appear that the powers to be have set the rules up this way so that you have to install an RCD with any new wiring without actually coming out and saying " though shall install an RCD". A good idea as alot of consumers would not pay for the installation of an RCD if they didnt have to.

If you want to see some Irish property prices:
http://www.myhome.ie/

Is a good place to start..

They can be pretty steep in Dublin in particular
http://archives.tcm.ie/businesspost/2005/05/15/story4682.asp

(Some highlights)

Mash,

RCD is one solution i guess, but not likely to occur, they cost money.

Aland,

the section goes on to denote zones similar to that which you mention, although they don't have to be identified.

Wood stud walls are probably less of an issue, we sparky's in oz are a bit lazy when it comes to drilling in dirt and dust, and wood is usually only used in domestic residence with structural walls so dropping from the ceiling space is easier.

Commercial however uses a lot of non-structural seperating walls, these are framed out in tin with cabling penetrations. This makes it easier to run around the wall with only a feeder drop from ceiling space. As the holes are rarely aligned with each other, let alone electrical outlets, cables can be anywhere.

Thanks for the feedback anyway guys, guess i'll just have to make a ruling on site.

Spock