DIYnot
Local | Network
   DIYnot > Forums
Local | Network
DIYnot Network Local DIYnot Network Local  
  Forum IndexForum Index     RulesRules    HelpHelp     Join FREERegister Free     About CookiesCookies     SearchSearch     LoginLogin 

Consumer Unit Positioning

Goto page 1, 2  Next
 
Post new topic   Reply to topic    DIYnot.com Forum Index > Electrics UK
Search this topic :: View previous topic :: View next topic  
Author Message
ryanj

from United Kingdom

Joined: 05 Oct 2003
Posts: 209
Location: United Kingdom

PostPosted: Tue Jun 01, 2004 6:10 pm Reply with quote

During my rewire, I plan to move my consumer unit to a new position. Currently, it is in a room with a concrete floor, I propose to move it to allow me to get cables into the crawlspace easier.

My supply is an overhead TT supply. Would it be acceptable to simply run 25mm sqr metre tails from the metre in the old position to the new consumer unit, or would I have to contact the power company to move the metre beside the consumer unit?

Also, is it fine to have earth rods driven from the crawlspace, rather than have them taken outside? And must I use a "whole-house" RCD, if I can get the earth fault loop impedance low enough?

And, is it acceptable to use a flush consumer unit in domestic situations, as it'd help keep everything neat?

And, is it acceptable to run cables in the crawl space without clipping them to the joists, or running them through the joists?

Finally, where the cables leave the consumer unit, do the cable grouping de-rating factors take effect for 1-2metres down the wall?
Back to top
 Alert Moderators

If you do not want to see this advert, click here to login or if you are new click here to join free.
plugwash

from United Kingdom

Joined: 28 Mar 2004
Posts: 8375
Location: United Kingdom
Thanked: 186 times

PostPosted: Tue Jun 01, 2004 6:49 pm Reply with quote

you aren't meant to run tails more than 3m without having your own isolation and protection

the main rcd for a TT must be in a plastic enclosure

you could use a plastic 4 module enclosure with the 100ma type S rcd and a 100A mcb (http://www.tlc-direct.co.uk/Products/CMDK401.html)

then run from that to a normal split load CU preferablly using 25mm swa
Back to top
 Alert Moderators
securespark

from United Kingdom

Joined: 11 Jan 2004
Posts: 24388
Location: Cheshire,
United Kingdom
Thanked: 397 times

PostPosted: Tue Jun 01, 2004 9:05 pm Reply with quote

2m for Norweb.
Back to top
 Alert Moderators
ryanj

from United Kingdom

Joined: 05 Oct 2003
Posts: 209
Location: United Kingdom

PostPosted: Wed Jun 02, 2004 7:51 pm Reply with quote

Anyone else? icon_redface.gif
Back to top
 Alert Moderators
il78

from United Kingdom

Joined: 06 Oct 2003
Posts: 701
Location: United Kingdom

PostPosted: Wed Jun 02, 2004 10:28 pm Reply with quote

Go for what plug suggested, creating a distribution circuit, have the position where you want then.....
Back to top
 Alert Moderators
ryanj

from United Kingdom

Joined: 05 Oct 2003
Posts: 209
Location: United Kingdom

PostPosted: Thu Jun 03, 2004 9:01 pm Reply with quote

Thanks! Got that problem sorted out.

Any advice on the others?
Back to top
 Alert Moderators
il78

from United Kingdom

Joined: 06 Oct 2003
Posts: 701
Location: United Kingdom

PostPosted: Thu Jun 03, 2004 10:16 pm Reply with quote

You can have the rod in the crawl space as long as its <100Ohms. (Make a label stating the location)

Not to sure what you mean about the RCD, but a TT system requires that the installation is protected by an RCD usually 100mA although a 30mA is required for supplementary protection.

Cant see a problem with using a flush mount DB

Clip the cables in the crawl space

Grouping factors for that amount of lenght shouldn't be a problem.
Back to top
 Alert Moderators
ryanj

from United Kingdom

Joined: 05 Oct 2003
Posts: 209
Location: United Kingdom

PostPosted: Thu Jun 03, 2004 10:41 pm Reply with quote

Quote:
TT system requires that the installation is protected by an RCD


Are you sure the whole installation must be protected?

The only thing I can find in the regulations states that all socket outlets on a TT system must be RCD protected. Nothing else.

Quote:
471-08-06 - Where the measure is used in an installation forming part of a TT system, every socket-outlet circuit shall be protected by a residual current device and shall comply with Regulation 413-02-16
Back to top
 Alert Moderators
plugwash

from United Kingdom

Joined: 28 Mar 2004
Posts: 8375
Location: United Kingdom
Thanked: 186 times

PostPosted: Thu Jun 03, 2004 10:55 pm Reply with quote

yes but you will never meet disconnect times otherwise

the impedcence of the earth limits the current flow down it to a value insufficint to trip a fuse or mcb

that is why you need the main rcd
Back to top
 Alert Moderators
ryanj

from United Kingdom

Joined: 05 Oct 2003
Posts: 209
Location: United Kingdom

PostPosted: Tue Jun 08, 2004 9:42 pm Reply with quote

But, if i could reach required disconnection times, would I need to use a main RCD?

Also, could I run meter tails instead of using SWA?
Back to top
 Alert Moderators
plugwash

from United Kingdom

Joined: 28 Mar 2004
Posts: 8375
Location: United Kingdom
Thanked: 186 times

PostPosted: Tue Jun 08, 2004 10:19 pm Reply with quote

tails would probablly be ok but they should be protected from damage

a worst case allowed TT is 200 ohms this will allow just over an amp to flow in the case of a short to earth (obviosuly until this fault is disconncted your entire earth system will be live so it should happen asap)

so either a rcd is essential OR it would have to be a bloody good TT (like big mats burried below the water table)

with a ROD you will not manage it
Back to top
 Alert Moderators
ban-all-sheds

from United Kingdom

Joined: 27 Aug 2003
Posts: 45095
Location: London,
United Kingdom
Thanked: 1590 times

PostPosted: Wed Jun 09, 2004 3:07 pm Reply with quote

plugwash wrote:
with a ROD you will not manage it

Particularly with a rod in a dry location - ryanj, what do you mean by the term "crawlspace"?
Back to top
 Alert Moderators
ryanj

from United Kingdom

Joined: 05 Oct 2003
Posts: 209
Location: United Kingdom

PostPosted: Wed Jun 09, 2004 9:35 pm Reply with quote

Crawlspace - Small area under the floorboards of the ground floor.
Back to top
 Alert Moderators
plugwash

from United Kingdom

Joined: 28 Mar 2004
Posts: 8375
Location: United Kingdom
Thanked: 186 times

PostPosted: Wed Jun 09, 2004 9:38 pm Reply with quote

it would be an insanely stupid place to put a rod

to get a usable earth the rod needs to be at least partially in wet soil
Back to top
 Alert Moderators
ryanj

from United Kingdom

Joined: 05 Oct 2003
Posts: 209
Location: United Kingdom

PostPosted: Wed Jun 09, 2004 10:57 pm Reply with quote

Fine, I'll use multiple earth rods in the back garden to try and keep the resistance low.
Back to top
 Alert Moderators
Search this topic :: View previous topic :: View next topic  
Post new topic   Reply to topic    DIYnot.com Forum Index > Electrics UK All times are GMT
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
Similar Topics   Replies   Views   Posted 
consumer unit positioning 5 740 Fri Oct 17, 2003 10:11 pm
New Cooker Circuit Install - Positioning of controls 2 5720 Fri Aug 17, 2007 10:44 am
Positioning of lights 2 300 Thu Oct 04, 2007 11:33 am
Positioning of bathroom underfloor heating controls 2 1460 Tue Nov 14, 2006 9:13 pm
cooker hood isolation switch positioning 2 1080 Tue Jun 28, 2005 9:46 am


 
DIYnot
Find an Expert | Find a Supplier | Search DIYnot.com
Network | Advertising | Newsletter
DIY | DIY How To | @home | DIY Wiki | DIY Forum
By using this site you agree to our Terms of Service / Disclaimer.
Please read our Privacy Policy. Copyright © 2000-2014 DIYnot Limited.