Buried Electrical connections

[Dave Plowman (News)]

Since pretty well no one uses steel conduit the answer is you check.

[Guy King]

The message from "Alan Holmes" contains these words:

No, you buy a house and you know where the cables are because they are required to be in certain areas. Or, more accurately, they're required not to be in certain areas.

Cables are permitted above and below visible fittings provided they stay within the outline of the fitting, width or height. Cables are permitted in the 150mm from the ceiling and 150mm from the edges of walls. Outside these areas cables must be covered by steel capping.

[Frank Erskine]

Do you remember the very old-fashioned close-jointed "tin-whistle" conduit? This was about the same gauge stuff as capping, but just rolled round into a pipe. Tee-pieces, elbows and so on were attached using setscrews. The pipe was terminated with a rubber bush.

Although it gave rather minor protection to wires, it was still convenient for "cut and draw" replacement of wires, although it was typically only about ½" diameter. A 1.0 sq mm T+E went through nicely!

Early c20, I would think. When I rewired my parents' 1902 town house (about 30 years ago) there was a lot of this about.

[John Rumm]

Not really. Unless you tend to hang pictures in the nude and live in a mud hut, you are unlikely to have a good enough earth reference to get more than a tingle even if you drove the nail right through a live conductor and then tried to hang on to the bit sticking out.

Sorry Alan, but you seem to be missing a number of fundamental points here. Might I suggest you read the IEE On Site Guide to get some grounding in the actual practices and requirements for a modern electrical installation:

Now if you wish to put your life at risk because of an idiotic notion that

Firstly have you stopped to think how the vast majority of houses are wired? The answer is with cables buried in the plaster. How do you think your house is wired?

If you want an easy to digest summary, then see here:

buried in plaster is the normal method of installation. It is fully compliant with BS7671. It is a safe and low risk method for cable installation so long as you follow the rules.

The rules state that there are permitted zones where cables may be buried without addition protection. These are vertically and horizontally aligned with any visible electrical accessory mounted on the wall, in a 6" zone at the corners of the room, and a 6" zone where the wall meets the ceiling.

If you want to run a cable outside of these zones then you need to either: ensure that it is buried >= 50mm deep from both sides of the wall, or protect it with earthed metal capping. The capping will not stop nail penetration, but will ensure a phase earth fault which will open the protective device quickly.

Your definition of "properly" seems a little odd. Unless you were to attempt to bury very heavy gauge steel conduit in the plaster (for which there will be insufficient depth), what you suggest will offer little if any protection against nail penetration.

[Dave Plowman (News)]

I'd not rely on regulations having been followed, though.

[Andy Wade]

"earthed conduit trunking or ducting satisfying the requirements of these Regulations for a protective conductor, or be mechanically protected sufficient to prevent penetration of the cable by nails, screws and the like" [522-06-06 (iii)]

But not capping, the sole purpose of which is to protect the cable prior to and during plastering.

[John Rumm]

I take it that 522-06-06 (i) only applies to cable with integrated metallic sheath like SWA then?

(At a glance it is easy to read the "incorporates an earthed metallic covering" and not pay attention to the end of the sentence!)

I stand corrected!

(never had the need to run a wire out of a permitted zone as yet - but no doubt the time will come)

[Guy King]

The message from "Dave Plowman (News)" contains these words:

Probably not, but I've never hit a cable yet, mostly by a bit of common sense. It's not really that hard to work out where the cables are likely to be.

Pipes, on the other hand, are a different matter altogether. Pointed out to the bloke next door that I could occasionally smell gas. Turned out he'd put three nails through a gaspipe in the floor.

[Andy Wade]

Yes: SWA, FPxxx, MICC, etc.

Read it in conjunction with the preceding text - "A cable concealed [...] shall (i) incorporate an earthed metal covering [...], OR (ii) be [one of the specified concentric cables], OR (iii) be enclosed [in earthed conduit etc.] OR (iv) be installed in [one of the the safe zones].

[Using capping]

In any case earthing capping is hardly practicable. Inaccessible joints would have to be soldered, which, if memory serves me right, would need the use of acid cored solder or a similar type of flux which needs thorough washing off to avoid corrosion.

[Matt]

If you are dumb enough to start randomly knocking nails in to support pictures, or drilling holes in walls such as in a kitchen to mount a spice rack, and you fail to use common sense and use a wiring detector then you are clearly not fit to continue to populate the gene pool.

It's called natural selection. :)

The reality is that unprotected wiring, buried in plaster in walls that may be disturbed by all and sundry who have ever seen a DIY programme is permitted....but wiring behind a skirting board that may remain in place for half a century isn't. It's a funny old world.

[Dave Plowman (News)]

Yup. Although maybe not for those who nail into walls. ;-(

The next owner of my place will be delighted - all the pipe runs are marked on the floorboards. Unless he wants those nasty stripped floorboards, of course.

[Christian McArdle]

Actually, the main reasons I've found is either to protect the cable or to provide a neater appearance to surface mounted wiring.

Christian.

[Dave Plowman (News)]

Yes - I've oft wondered about the reasoning here. Who nails into skirting?

[Dave Plowman (News)]

For neatness, you can't beat MICC properly done. It's becoming a dying art, though.

[dcbwhaley]

It was good advice because it was taken directly from the IEE regulations and the On Site Guide. Burying cables in plaster is a standard method (Method 4 ISTR) of installation. But the cables must be in the permitted zones, basically horizontal or vertical runs fron the fitting.

If you drive a nail in those zones witthout using a cable detector you deserve what you get. Fortunately all you are likely to get is a mild tingle at worst. More likely a tripped breaker..

[Autolycus]

And used in my house in the mid fifties... Probably another in the list of "Last House in England to have..."

2A sockets Rubber insulated cables Bedroom fireplaces Ground floor with no dpm 9" walls Steel window frames Paddy's mortar

and so on.

[John Rumm]

I suppose you could crimp a ring terminal onto your wire, drill the capping, then pop rivet the terminal onto it.

[Alan Holmes]

But you now have a shortcircuit and damaged wiring, as it is not installed in conduit it means that the wire has now to be pulled out of the wall and replaced.

Stuff deleted:-

All in conduit.

Installed by me!

The normal way of installing conduit is to cut a trough in the wall deep enough to take the conduit and then plastered over.

Alan

[Alan Holmes]

You should not bury joints, a continuous wire should be installed, if the wire you have availabe is not long enough, go out and buy some which is long enough!

Alan

[Alan Holmes]

What's MICC?

Alan