I am finally about ready to start my rewire, but have hit a snag at the planning stage.  

The current consumer unit is under the stairs, which curve round 90 degrees. The existing cable runs to the upstairs go under the flooring of the understairs area, under the hall floor, and then up the other side of the hall wall, running between the living room and dining room doors in deep  PVC trunking.

This is the only really sensible route - there is about 6 " (i.e., the width of a block wall) between the two doorways.)  However, to have the conduit sticking out into the hall at this point as at present is a pain, and I am wondering about following the same route with the new cables but either rebating them into the wall and protecting them with standard metal protectors or doing a little better and using metal conduit.  I could then plaster up and have a neat and tidy job. I am however concerned about anyone trying to, say, put up a picture in the dim and distant future and finding my main cooker feed, so want to protect the cables as much as possible........

So:-

1. How many cables can I run in one conduit? I am reckoning on running nine or ten cables in all, 2 off 1.5 and 7/8 off 2.5mm, plus cooker feed.
2. Do ordinary metal protectors now have to be earthed?  I know conduit has to be. If so, is it sufficient to just screw a terminal to the metal, or do I need a special fixing?
3.  Am I best off using standard, round 25mm conduits or is there a conduit on the market which is rectangular in cross section which would suit me better.  In any case anything I use would have to be plastered over.  

Thanks

John Davies

Was you drunk last night LS or just very tired?
Half of that advice you gave is wrong
You cant run diagonally even if you place metal capping over cable
You cant use oval plastic conduit if the cable run isnt in a designated area

[quote author=tellondon  link=1099181794/0#2 date=1099233715]Was you drunk last night LS or just very tired?
Half of that advice you gave is wrong
You cant run diagonally even if you place metal capping over cable
You cant use oval plastic conduit if the cable run isnt in a designated area [/quote]

lol yes tired not drunk, anyway I don't have time to check the posts and check what I said so if it's wrong you advise him  

thx LS

Metal capping is not acceptable on diagonal runs. It must be metal conduit, metal trunking or metal ducting, in other words "fully enclosing" the cables.  It must also be earthed if diagonal (and less than 50mm from the wall surface).

If it's in one of the zones (vert/horiz/150 from corner or ceiling) then no protection is required.

[quote author=HandyMac  link=1099181794/0#7 date=1099246907]Must admit, 50mm doesn't sound very deep to me! If I'm drilling holes in masonry it's not unusual for me to go deep to make sure the rawlplugs are biting on real brick and not some fancy plasterwork.....

Andrew
[/quote]

a hole is a very different thing from a channel

you can make a hole right through the wall to put a gas meter box in and the wall should be fine

but if you cut the wall in half from top to bottom i suspect you would have problems

My mistake, I gues capping really is of no use then  

Hey John

Trunking is only ideal if its surface, if you are running cables in the walls and want to use steel conduit that’s ok.

But a masonry drill won't do diddly to metal conduit. You can tick away all day with your SDS on that and it'll just annoy you.

Back to J.D.s question. Can you not access between the floors from the under-stairs position?. If you're in luck and the joists run the correct direction you may be able to do away with much of the run and just go direct between the floors. May be worth a poke about. If not then, possibly go for singles in a conduit run, or two, right from the CU through the stairs/wall part of the run, and finish the conduit in a box once you're back in more normal territory. You can hire the benders for the conduit for about £7 to £10 +VAT per day. The conduit then could be channeled in the edge of the wall between the doors. Structurally there should be few consequences if this is just a block deviding wall. Just have a good look and maybe take some of the wall surface off to see how sound the core is first. once the conduit is cemented in place (not plastered, cement stronger between the doors) you'll probably be more solid than the original brick.

Must have been a 'meaty' drill like one of the 4kg + ones. My Bosch GBH would never manage something like that, it'd 'bounce', but it's only 2.5kg. My other 240V drill may, but I only use that for chasing/chiselling so it's not really an issue as those bits wouldn't do in a conduit.

Do you use heavy drills for your normal stuff? I only ask as I've been thinking of getting a bigger 110v or battery drill, which would double up for the deeper chasing or 25mm bits, but thought they'd be a bit of a faff in terms of lugging to and fro and also using for longer fixes.