Chasing for sockets and switches for rewire later

Joined
18 Jan 2014
Messages
11
Reaction score
0
Country
United Kingdom
Hi folks,
I’m in the process of refurbishing upstairs - ripped down cracked lathe and plaster ceilings and reboarded. I want to rehang doors so they open into the rooms and that means moving light switches. And I want to have more wall sockets. But I can’t afford to get the rewire done at this point. So can I install back boxes and chase in conduit down to floor/up to ceiling so that an electrician can run cables at a later date when I’ve ripped the downstairs ceilings down and there is full access. This means I can get all the dusty work done now, fill the chases and skim the walls and get the rooms back into use and all I’ll need to do is fill and skim the old boxes etc (just two in each room plus a light switch) after the rewire. I assumed this would be fine but I’ve read that cables need to lose their heat into the masonry and if they are in conduit covered with bond and skim maybe that can’t happen? Any advice much appreciated!
 
Last edited:
Sponsored Links
Joined
20 Aug 2009
Messages
9,280
Reaction score
1,191
Location
Dorset
Country
United Kingdom
Don't worry about all that rubbish.

Just use oval or round plastic conduit.

Round will require fittings.

Oval won't.

Avoid joins in the conduit, and make sure you the conduit end lines perfectly with the hole in the metal knockout box.

If in doubt, always run two 20mm oval conduits, that should be plenty for most wiring designs - but check first.
 
Joined
11 Jan 2013
Messages
5,225
Reaction score
1,098
Location
Durham
Country
United Kingdom
Be best to get your electrician on board before you start- they will be able to advise on safe zones, cable sizes and other footling details.

EDIT I'd put a lot more than 2 sockets in any reasonable sized room. Have a think about AV cables as well (coax, CAT5 or better)
 
Joined
18 Jan 2014
Messages
11
Reaction score
0
Country
United Kingdom
Many thanks for quick and clear answer Sparkwright! I thinking of single round conduit so there be plenty of room to pull through any variation of cable spec and I could use the cheapo chasing tool I’ve got which does a tidy job. Can I fix the round conduit with grab adhesive or does it need to be clips which would mean a deeper or wider chase? In which case I may as well do a wider but shallower chases for oval conduitBasically I want to avoid giving the electrician a nightmare to deal with. What would you prefer to see if you turned up to the job?
 
Joined
18 Jan 2014
Messages
11
Reaction score
0
Country
United Kingdom
Makes sense, oldbutnotdead, but I didn’t want to take up someone’s time doing a site visit when the rewire won’t happen for another six months probably (first baby due in Feb agghh!) and I’d be getting several quotes so no guarantee of getting the work.
Now googling coax and CAT5 - beats going upstairs and actually doing some work!
 
Last edited:
Joined
18 Jan 2014
Messages
11
Reaction score
0
Country
United Kingdom
Re number of sockets, oldbutnotdead, thanks for checking that - the two sockets is what’s in each room currently so only a small amount of filling in to do later. The plan is to have two double sockets on at least two walls in each room, where possible lining up with new ones on other side of walls, and at DDA height while I’m at it.
 
Joined
11 Jan 2013
Messages
5,225
Reaction score
1,098
Location
Durham
Country
United Kingdom
Up to you on DDA height, you don't have to, imho sockets halfway up the wall look fuggley and increases the odds of trip loops forming (thing plugged in, thing away from wall, big gap, trip arrgh crash.).
If your drops are all straight lines going into floor/ceiling (which will be accessible at wiring stage) then you'll be ok on the Design bit. Do make sure your drops are in the safe zones (horizontal or vertical, up to you, Google is your friend).
 
Joined
18 Jan 2014
Messages
11
Reaction score
0
Country
United Kingdom
Good point, oldbutnotdead - I’d trip up on a paper clip given half a chance. One final question if you don’t mind. Single vertical conduits entering top/bottom of back boxes on centre line or in line with one of the outer edges using the last punch out hole? I’ve seen both online, is it a personal preference or a technical reason?
 
Sponsored Links
Joined
11 Jan 2013
Messages
5,225
Reaction score
1,098
Location
Durham
Country
United Kingdom
Given that you'll be using twin and earth cable through your conduit, I'd go with whoever it was above suggested double run to each socket. 2 x 2 5 t & e will be tight in 20mm round.
Don't really understand the question. The centre of the conduit (oval or round) wants to align with the centre of the knockout being used in both planes (left-right and front-back). 2g boxes have at least 3 knockouts on the long side, I usually use the centre (if a single entry) or top right and top left for 2 tube runs. If you're using 25mm boxes it's sometimes easier in the backbox having the cables entering separately. Whichever you do, try and be consistent. Given your setup, it'll be worth taking pics before you fill the chases in (to prove to electrician that tubes are in safe zones).
 
Joined
18 Jan 2014
Messages
11
Reaction score
0
Country
United Kingdom
I meant the knockouts - I’ve seen examples where a single entry goes into the far left knockout on the topside rather than the centre knock out. So the backbox is to the side, like a flag on a pole. Your method makes complete sense, thank you, and also your advice re consistency and photos. Much appreciated! All the best for 2022.
 
Joined
28 Jul 2009
Messages
6,372
Reaction score
507
Location
Kent
Country
United Kingdom
In my opinion 20mm round is far easier to pull cables into than oval. And one doesnt actually need fittings, as long as the end enters the backbox and it's secure so it can't move it will be fine.

Running 2 tubes is virtually no additional work but it gives so much flexibility and future proofing especially if access to the ends of the tubes is limited.

Photos are good, the more information that's available to a contractor the easier it is to start the job and potentially improve the estimate.
 
Joined
18 Jan 2014
Messages
11
Reaction score
0
Country
United Kingdom
Thanks Sunray, yes I think I’ll go with round conduit, two to each backbox. And having them enter via the left and right punch outs like oldbutnotdead said means I’ll have two narrow clean chases to fill instead of one wider one.
I’ve also got to put a drop in the to-be bathroom for a future power supply to a mirror cabinet. I don’t know the exact size of the mirror or the design and a lot of them seem to have a cable entry point off centre. I’ve done two chases which I plan to conduit and tile over. Then cut into whichever one is best when I have the mirror and the electrician can run the cable down. Is that ok?
 
Joined
28 Jul 2009
Messages
6,372
Reaction score
507
Location
Kent
Country
United Kingdom
Does anyone ever use 25mm round and 47mm box for deep chases
No reason not to, bear in mind horizontal chases depth are restricted to a certain % of the wall. For cable of 6mm² or bgger I'd aim for 25mm conduit and deeper box as accessories such as 45A cooker/shower and the wiring do take up more space, no point in struggling.
 
Last edited:
Sponsored Links
Top