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FatAlan

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Appart from the building regs specification on the size and positioning of notches and holes in joists is there a best practice on what to use? Is it just the case that notches are used in place of holes due to the cable positioning being outside that prescribed for holes. Are there any issues with not clipping cables under floor boards? I say this as when for instance you install down lights it seems prudent to have a fair bit of slack left for future work / fittings etc.
 
As @Pete999 , if a metal plate is fitted it is fine. If a joist has been notched it will quite apparent the floorboard has been up and it would take some kind of numpty to bang nails in without careful investigation
I gave you an "optimistic" there - if you ask around it doesn't take long to find a stack of weekend DIYers who have needed to fix a loose floorboard and not wondered why there was a screw missing :) Not sure numpty is the word I'd use, maybe just inexperienced and possibly being hassled to do a job they've not encountered before!
https://www.google.co.uk/search?q=nail+through+pipe+floorboard
 
Bought a few of these but as stated above they will need insetting themselves to enable the floorboards to fit back flush.

[ElectriciansForums.net] Notches or Holes, clip or not to clip?
 
more effort to notch then it is drill a hole
if the hole is drilled in correct place- less likely to have a screw/nail go through it than if it was in a notch (unless you ues a metal plate)

always try get a few clips in under the floorboards to keep it off the plasterboard and alway from any screws etc- but impossible to clip in on its full run if its a rewire to an exisitng house and you only needed to take up a few boards- otherwise you will end up taking up all the poxy floorboards in the house!

Sometimes it is more effort to drill a hole ... in Victorian properties in Scotland ... not sure whether it goes further afield ... there was a practice of installing 'deafening' or 'deadening'. Strips of wood are nailed to the joists at approximately mid height and thin boards are laid between the joists with their ends resting on the strips at each side. The boards are then covered with a very 'rough' lime mortar. I believe the purpose of this practice was to reduce noise transfer. It makes the drilling of holes at mid joist height a much more involved process when this material needs to be cleared away before piercing the joists.
 
The way new builds are thrown up these days, I seriously doubt that there is time to mark where pipes and cables are, that is unless it's specified and paid for, stuff is thrown in, get paid and Foxtrot Oscar on to the next job, "not my fault if some Muppet nails or screw through a Pipe or cable, is it Boss?" Not much pride taken in the majority of new builds these days, and that includes some, not all, so called Electricians I'm afraid, how many new builds are wired using Mates and Apprentices, without any supervision.

I agree. I did an EICR on a 10 year-old property last week and discovered that one of the live conductors of the RFC supplying the lower-level sockets of the property had been connected to the MCB for the RFC supplying the upper-level sockets of the property and vice-versa. How this error wasn't detected during the initial end-to-end tests on both circuits beats me.
 
I agree. I did an EICR on a 10 year-old property last week and discovered that one of the live conductors of the RFC supplying the lower-level sockets of the property had been connected to the MCB for the RFC supplying the upper-level sockets of the property and vice-versa. How this error wasn't detected during the initial end-to-end tests on both circuits beats me.

When I 'checked out' the electrical system in the property that I am in at the moment, I discovered that one of the socket circuits was connected to 2 separate MCBs! It took a while to trace down why the circuit appeared to be permanently 'on' whichever MCB I switched off.
 
When I 'checked out' the electrical system in the property that I am in at the moment, I discovered that one of the socket circuits was connected to 2 separate MCBs! It took a while to trace down why the circuit appeared to be permanently 'on' whichever MCB I switched off.

As I've encountered this very same issue several times in the past, I realised straight away that there was a cross-connection between the two RFCs. This was confirmed by switching both MCBs off then doing end-to-end tests on both circuits.
 
Sometimes it is more effort to drill a hole ... in Victorian properties in Scotland ... not sure whether it goes further afield ... there was a practice of installing 'deafening' or 'deadening'. Strips of wood are nailed to the joists at approximately mid height and thin boards are laid between the joists with their ends resting on the strips at each side. The boards are then covered with a very 'rough' lime mortar. I believe the purpose of this practice was to reduce noise transfer. It makes the drilling of holes at mid joist height a much more involved process when this material needs to be cleared away before piercing the joists.


Hello GB.Kayak,

I found out about `Deafening` about 27 years ago when my Business partner and I went up to Edinburgh to carry out installation of a very large `Domestic` Heating system containing approximately 50 Radiators - build the Boiler from parts in the Basement - a complete re-plumb including 6 Bathrooms and 4 x 450 litre Hot Water Cylinders in a very large House that had been bought by a very good Friend of ours.

Although it was just a Big Family Home there was nothing `Domestic` about the Heating or Plumbing in that House !

I had previously visited Edinburgh / the House and spent a Week measuring up and making notes, sketches and taking photographs and some videos to get enough information to design the Heating and Plumbing systems and place Material Orders when I went back Home.

Because the Floorboards were `irreplaceable` - 12" wide x 1" thick highly polished Oak it had been agreed that although We were `good at taking up Floorboards` - a `Joiner` / Furniture Quality Carpenter was going to be engaged to take up all the Boards that we would require and on my `Survey visit` I identified most of the pipe runs and sections of Floorboards that we needed lifting.

I describe the above about the Floorboards because it meant that I had never been able to lift a Board during the Week that I was at the House - all I `knew` was that there should be plenty of room under the Floors as some of the Joists were 15" on the Ground and First Floors and were 12" on the Second Floor.

From my brief description of the Heating & Plumbing systems You might be able to imagine the `Hundreds of Metres` of Copper pipe to be installed.

Can You imagine my `Shock` when we arrived to start work on Day 1 and found the `Deafening` that You described under every Floorboard / between every Joist - level with the top of every Joist !

We then had to create Pipe runs through the `Deafening` - although we had Labourers on the job and we found that channels could be `grooved` through the material using wood battening and a hammer the `Deafening` added a lot of money to the Labour of the job.

We also needed a lot more Floorboards taken up by the `Furniture Maker Carpenter` to enable these channels to be created.

As We were doing the work / working away from Home as a favour for our good Friend we did not lose any money on the job - although we were working on `Mates Rates` and staying at his Family`s Home - He paid for the Labourers to create our Pipe channels.

However if we were working on a Quote basis for a Client / Building Contractor we would have had a large wage bill for extra Labour to create the pipework channels in the `Deafening`.

That was the biggest `surprise` that I have ever had on any Job and it was a very Big Job regarding the pipework runs !

Sorry that this message became so Long winded.

Regards,

Chris
 
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What's all this about 'notching'? - I thought cables had to be at least 5omm from the top or bottom of a joist? - that makes an awfully deep notch! - probably seriously weakens the joists. Isn't that why cables are passed through drilled holes? Pipes are ok - you just get wet!
If you cover a cable with a metal plate it should also be earthed, at the same rating as the circuit CPC. Better to drill holes - use a right angle drill. I bet a good 'numpty' could drive a nail through a protection plate - if it bends he could drill it for a woodscrew!
 
What's all this about 'notching'? - I thought cables had to be at least 5omm from the top or bottom of a joist? - that makes an awfully deep notch! - probably seriously weakens the joists. Isn't that why cables are passed through drilled holes? Pipes are ok - you just get wet!
If you cover a cable with a metal plate it should also be earthed, at the same rating as the circuit CPC. Better to drill holes - use a right angle drill. I bet a good 'numpty' could drive a nail through a protection plate - if it bends he could drill it for a woodscrew!
You mean bonded surely? self tappers would be best if you are fixing to the cover plate.:D:tongue:
 
in answer to posts#39 and #40.

the plates should not be earthed as they are not exposed conductive parts of the installation. they are just metal plates with cables sitting on them.

nor should the y be bonded, pete, as they are not extraneous.
 
in answer to posts#39 and #40.

the plates should not be earthed as they are not exposed conductive parts of the installation. they are just metal plates with cables sitting on them.

nor should the y be bonded, pete, as they are not extraneous.
Tel, I was trying to be sarcastic, obviously didn't work, did it? I agree with what you are saying. Just trying to point out what a ridiculous statement it was in the first place, next you will have to earth the screws and nails that are used to fix the floorboards, stupidity at it's best, earth the plates my arse.
 
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