I've had my house rewired, and I have noticed that they have just run the cable where the old cable ran which is through an open notch about 1/4" deep from the top of the joists. Was this ever legal for a house built after the
1945 and is it still legal? I'm under the impression that they have to drill holes through the middle of the joists and thread it through.Thanks for your time
Not sure about the legality, but it's not something I'd ever do. Leading with the chin.
AFAIK it's only quite recently that it's been a no-no as regards building regs. I would defy anyone to show me a 1945 house (or even decades younger) which isn't full of notched joists!
The reason relates to weakening of the joists and hence structure of the building; so if historical notches are already present, it would seem pretty pointless not to make use of use them and to drill new holes instead, thereby weakening the joist further. Cables run in notches should be protected mechanically using steel plates or similar, to prevent nails being put through them.
David
Yes, Part P (2005) requires "reasonable provision" to be made for electrical safety. Wiring reg. 522-06-05 which requires cables to pass at least 50 mm above the bottom and below the top of a joist is so well established that ignoring it would constitute failure to provide reasonable provision, IMHO. This requirement has been in the wiring regs. since the 14th edition (1966), possibly even longer.
Alternative ways of complying with 522-06-05 are to use armoured or concentric-type cables or protection plates, like these:
True, but not really relevant.
If you drill on the centre-line of the joist well away from any existing notches there is negligible loss of strength. The usual guidelines allow drilling holes of up to a quarter of the joist depth in two zones between 25% and 40% of the span. Normal holes for cables will be _very_ much smaller than that. Notches of up to an eighth of the depth are allowed between 7% and 25% of the span.
but not so well established that you have quoted correctly the requirement for cables "passing through a joist". Of course the intent is another thing and you are probably right. Maybe there is still time to improve this sloppy drafting innthe current draft.
Jim A
Putting a nail through a cable isn't as bad as the situation I have on my landing though.
In a similar way, I have a hot water pipe notched into the joists all along the length of my upstairs landing. I suspect it is the feed to the kitchen sink hot tap. I have marked the floorboards to ensure that anyone putting nails down will avoid the pipe. Hopefully, not a thing that might happen when the boards are covered with carpet.
Dave
Hmm - how do you work that out? (I'm just comparing potentially being electrocuted with getting a wet ceiling...!)
David
Dave wrote
When we moved into this house, I noticed a lightly stained patch on the downstairs hall ceiling. Investigating the landing floor above, I lifted a suspiciously loose floorboard section and saw...
... that someone had driven a nail through the floor (why?) into a central heating pipe. On realising what they'd done, they'd elected to fix the leak using (I kid you not!) the lid of a baked bean can folded round the pipe and secured with 2 Jubilee clips.
The leak had obviously seeped slightly because they'd placed a red plastic Christmas pudding basin under it, and left the floorboard loose so that they could empty it on a regular basis.
Not disputing that at all; I just meant that I think it would be odd to drill new holes through joists in a situation where adequate notches are already present from a previous installation. Unless the old notches are actually going to be 'repaired' by reinforcement (like anyone's ever going to do that!), what's wrong with 'recycling' the notches, providing adequate protection from nails is used?
David
LOL that's worse than my situation o-)
Dave
Nail through cable does not equate to electrocution. Hammer in one hand, nail in other. Once nail is going into wood, other hand has let go of nail, in case that hammer strikes hand.
While nail is in one hand, the other hand is in mid air. No electric shock across the heart.
Nail can hit...
Nothing. Earth cable. Neutral. Live. Earth and live. Live and neutral. None of these is detrimental to life, as if it hit live, the nail is hardly likely to cause a hazard, unless other hazards are there to compound it. Like no fuse from the grid :-( Nail through pipe equates to flood below. much more dangerous. Many switches could go live to plaster and surrounding surfaces.
Dave
You'd probably not like the sight we've seen a couple of times of water running down the switched-on light fitting...
cheers, clive
In message , Dave writes
Even if the nail pierced the live conductor while being held the chance of getting a shock if kneeling on a dry wooden floor or carpet is low. The nail could sit there live for many years either going undetected or waiting for a series of unfortunate circumstances to line up. Someone holding an earthed metal appliance and standing on that area of carpet which had just had coke spilled on it for instance.
You are right, but I've never seen a rewire where _existing_ notches were not reused. They were pretty well always placed in the centre of a floorboard, and anyone who hammers in a nail longer than 1/2" in the centre of a floorboard really is asking for trouble with just about any of the services.
In article , Clive Mitchell writes
I remember years ago a couple who had one of those "Teasmade" machines next to their bed. The case was live and had been so for many years caused by some very bad wiring with rubber covered cable in the 13 amp socket.
I found out just how bad that was when I plugged an electric drill into it, leaned outside the bedroom window to move a ladder so I could drill through the window frame and when I grabbed the ladder I couldn't let go of it with a severe belt!.
Fortunately someone else with me saw what was going on and put 2 and 3 together very fast!.
So they, the couple who lived there, were "live" for years and didn't notice a thing!..
In message , tony sayer writes
The current required for muscle contraction like that is pretty low. About 10mA or so. That's the equivalent of just under half the current that flows through a 7W nite lite lamp. If the tools earth was fully live then your fate at that point in time was purely decided by the outside weather. If the ground had been pretty wet you could have passed in the region of 100mA or so and.... Well it's unlikely you would have been posting here.
You'll need to enlighten me. Were you touching the "Teasmade" or a *very* old non-double insulated drill?
I remember coming across my dad's old Stanley Bridges c/w neon "safety light" once but that was several decades ago.
Jim A
In article , Clive Mitchell writes
It was damp earth that the ladder was into, but not wet IIRC but a long time ago now!..
It was more I reckon to do with the guy who was around at the time who recognised what was happening and unplugged the poxy thing!. Later that week all the metal bodied stuff we had had loads of PVC tape wrapped around them!....
In article , Jim Alexander writes
The drill which was an old "Wolf" one had a metal case and was plugged into the 13 amp socket.
The "earth" in that socket was connected to the live in the house wiring as the rubber cable did not have its earth connected at the distribution board, and the metal jacket of the rubber cable was in contact with the live due to insulation breakdown.
This it seems is why the earth was dis at the board as it had been blowing fuses and that was seeming the way the original fuse blowing fault had been cleared!..
Around 1971 IIRC again!...
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