Chasing Questions

[GeoEngineer]

I'm going to be chasing a couple of cables in and I have got a few questions to ensure that I do it in accordance with general good practice.

1. What size conduit is recommended for 2 off 2.5sq mm twin and earth cables? Is 25X10mm ok to use?

2. I have seen is stated somewhere that conduit runs should be sealed, so whats the practice where there is an elbow needed?

3. Is it usual practice to put an open grommet in the holes in the back boxes where the cables come through? - I'm guessing so to stop the cable insulation getting damadged.

4. The Earth is currently connected to the face of the socket only in the surface mount setup. As I am converting to melal back box do I need to jumper the earth across or can I leave the connection through the screw hole to handle that?

5. Do you normally stop the conduit at the top of the wall or does it need to go through the ceiling board so that it is flush with the top of the ceiling boards.

 

[jj4091]

I presume you mean trunking rather than conduit,1)25x16 would be better2) you cannot use an elbow if it is going to be concealed3)regarded good practice not a regulation4)If you have at least 1 fixed mounting it's ok5)carry it up through the ceiling by an inch or so. You do not actually need to use trunking, plastic capping is ok under plaster. http://www.tlc-direct.co.uk/Products/MTCAP25.html

 

[GeoEngineer]

I presume you mean trunking rather than conduit,1)25x16 would be better

Actually I did mean Conduit. 25 X 10 mm oval.

2) you cannot use an elbow if it is going to be concealed

In that case what is the practice for getting a socket under the window?

You do not actually need to use trunking, plastic capping is ok under plaster. http://www.tlc-direct.co.uk/Products/MTCAP25.html[/quote]

What is the usual way for using this, do you push holes through the back one to secure that? How is the front one secured and do the side joins need to be sealed?

 

[ColJack]

there is no back or side one.. that's a reflection..

you nail ( or screw ) through the side flanges into the block / mortar lines, every 300-400 mm.. using the capping nails shown on the website as "related items you may need"

to my knowledge, they don't do flat elbows for oval conduit...

the way to do it is shown in this picture ( linked to from a post in "my projects" )

Cooker cables

Cooker Cables

 

[GeoEngineer]

So with capping it's ok to leave a Gap where the cables go around a corner?

 

[jj4091]

The capping is only used to protect the cables from damage during things like plastering , so there is no need to worry about that. However cables should not be concealed unless they are in a safe zone(see the wikki ref. safe zones for cables) or more than 50mm deep. How you put a socket under a window will depend on where the ring main runs.

 

[GaryMo]

the way to do it is shown in this picture ( linked to from a post in "my projects" )

Cooker cables

Cooker Cables

Technically incorrect col unless the purpose of the picture is to show how capping is fixed?
The poster has not adhered to relevant safe wiring zones. You can only go horizontally and vertically from accessories unless at a depth of greater than 50mm unless wiring is protected by an earthed metallic conduit.
See BS7671 or the OSG for clarification.

 

[GaryMo]

How you put a socket under a window will depend on where the ring main runs.

Best to run down the corner in the 150mm safe zone then exit horizontally to feed the socket.

This all depends on where the window is located and size of room due to people who like fixing hooks for curtain tie backs!

 

[electronicsuk]

Technically incorrect col unless the purpose of the picture is to show how capping is fixed?
The poster has not adhered to relevant safe wiring zones. You can only go horizontally and vertically from accessories unless at a depth of greater than 50mm unless wiring is protected by an earthed metallic conduit.
See BS7671 or the OSG for clarification.

Looks to me like there's an accessory box at the ends of both the vertical and horizontal run.

 

[mdbalson]

Technically incorrect col unless the purpose of the picture is to show how capping is fixed?
The poster has not adhered to relevant safe wiring zones. You can only go horizontally and vertically from accessories unless at a depth of greater than 50mm unless wiring is protected by an earthed metallic conduit.
See BS7671 or the OSG for clarification.

Looks to me like there's an accessory box at the ends of both the vertical and horizontal run.

Yes there is a cooker outlet plate on the end of the horizontal run & a cooker isolator switch on the end of the vertical run.

Cooker outlet plate

Cooker Isolator switch

The chasing is behied one of the 500mm base cupboards & the Range Cooker

The range

 

[GaryMo]

Looks to me like there's an accessory box at the ends of both the vertical and horizontal run.

There does to me too but if the cable is less than 50mm deep and not protected by an earthed metallic conduit (looks that way to me) then an accessory would have to be fitted at the right angle to make the cable run comply.

You can run vertically and horizontally directly between accessories and wiring zones.

 

[RF Lighting]

No it wouldnt


//www.diynot.com/wiki/electrics:walls

 

[GaryMo]

No it wouldnt

Please expand.

EDIT - no need, I may be able to see where you're coming from now.
The vertical line above and below the CCU would be considered a wiring zone as would the horizontal line to the left and right of the connection plate.
That way the cabling would actually comply.

My appologies.

 

[RF Lighting]

See above edit

 

[GaryMo]

See above edit

And mine