Does this cable have to be run in steel conduit in a notched

[MrS]

Does this cable have to be run in steel conduit in a notched floor joist?

If I cable Is running from one side of the room to the other and it is run through the centre of each joist all the way along, but when it comes to the end one, the joist is against the wall. To get the cable up the wall and behind the skirting board the last joist has to be notched out and the cable run in the notch to the wall then up behind the skirting board. If all the cable runs through the joists, but has to run through a notch right against the wall does it need to be run in earthed metal conduit just for the little run of a few 3cm?

I hope that makes sense and im sure it’s a very common problem.

 

[Qedelec]

In another of your posts you mention the OSG so why have you not read it regarding running cables 50mm below the floor, notching wont permit this, unless you intend to compromise the strength of the joist.

 

[MrS]

yes i do understand that they have to be in holes 50mm below the top and 50mm above the bottom and i understand why. this is due to compression and tension. when a joist bends the top is in compression and the bottom is in tension. the centre line isnt in either compression or tension and so it is best to drill the hole in the centre so as not to weaken the joist. if i joist has to be notched there is guidelines as the how deep and where you can notch it.

it aslo states that if you notch a joist you have to put the cable in earthed steel conduit.

i think you read my post wrong. i can think of many occasions when you would have a joist right next to a wall. if you wanted to bring the cable up the wall for a socket outlett, it would be impossible to drill through the joist and so it would have to be notched out.

what i was trying to ask was if you need to notch just one joist at the end of a cable run, but the rest of the cable has been run through the joists, would this part of the cable need to be put into earthed steel conduit just for that little part right next to the wall where it will have to run through a notch.

i know this situation might not come along very often but i just wanted to know. sorry if im not making my point clear.

 

[dingbat]

Use a safeplate. You can get them at most electrical wholesalers:

http://www.tlc-direct.co.uk/Main_In...Index/Necessities~Cable_Protection/index.html

 

[MrS]

great, just what i was looking for. thanks

 

[JACKC]

Even with the safeplate you still need to be the 50/50 gap for drilling. I would chisel the wall behind the joist, protect with oval conduit and plaster over. I wouldn,t recommend notching up a joist.. Could be wrong as we will find out now doubt.

 

[baldelectrician]

forget those plates, I use heavy duty galv box lids.

I'm doing a rewire at the moment and some of the cable is running in an old conduit run for a few joists. The regs require mechanical protection, box lids do well if they are heavy enough.

Just the job and pennies from good wholesalers.

Make sure you get the heavier duty lids.

 

[MrS]

thanks.