Horizontal chasing of cable for electric fire

[kevt296]

Sorry if the arse has been kicked out of this topic but would really like some clarification on the subject of chasing electric cables into walls horizontally.

Situation is;
Need to have installed, electric supply to a "hang on the wall" type electric fire. My intention would be to have a 20A FCU plumbed into ring main, right next to a wall socket and then run the cable to the fire via a horizontal chase. The idea is to have isolation of the fire via this FCU yet it will be next to the socket which is hidden by furniture so out of sight. The house is mid 80's and wall socket is at standard height from floor, say about 400 mm from floor? Floor is concrete.

Having mounted fire, the connection area on the fire, which is in effect a cut-out within the back panel, aligns directly at the same height as the wall socket and planned position of the FCU. Therefore plan is to chase out horizontally to socket and FCU, a distance of approximately 1 metre. My thoughts would be to protect with metal top hat conduit or at least with oval plastic conduit. (Does metal conduit need to be connected to an earth at all?)

I have viewed the topics on safe zones and this does seem allowable and in practical terms would be far easier to accomplish rather than running down into the concrete floor or up into ceiling and then along and back down again. However, if anyone could confirm my intention or any feedback would be greatly appreciated.

 

[ricicle]

Since your cable run is horizontal to the socket and FCU there will be no issues.

 

[plugwash]

Is the circuit this will be fed from RCD protected?

 

[kevt296]

Is the circuit this will be fed from RCD protected?

We have an older style CU fitted but obviously it does have fuse protection.

 

[PrenticeBoyofDerry]

Horizontal chases are permitted within the zone of the accessory.
Check out the link:
//www.diynot.com/wiki/electrics:installation_techniques:walls

You will require 30mA RCD protection, for any new cable buried less than 50mm within wall unless the cable is mechanically protected (metal capping is not considered as mechanical protection). If a socket outlet is installed, that will also require 30mA RCD protection regardless.
There are also permitted depths of chases within walls, horizontal chases can be no more than 1/6th of the depth of the skin/leaf of wall.
If the circuit is a ring final, you cannot take a spur from a socket that has been spurred, unless the original spur has been fused.
Plus you will not get a 20A fuse for a FCU, they rate no higher than 13A.
A solution to RCD protection would be to install a FCU with integrated RCD facility: http://www.screwfix.com/p/volex-13a-rcd-fcu/83049

 

[ban-all-sheds]

If the circuit does not have RCD protection you are not allowed by the Wiring Regulations to install any concealed cables, except via some pretty unlikely methods.

http://electrical.theiet.org/wiring-matters/27/cables-in-wall.cfm?type=pdf

Compliance with the Wiring Regulations is not in itself compulsory, but what is compulsory is for you to make reasonable provision in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury, and in reality, practical terms etc, you might struggle to show that you had done that if you had contravened a very safety-related provision of the Wiring Regulations.


[EDIT]Wiring Matters link updated[/EDIT]

 

[plugwash]

If the circuit does not have RCD protection you are not allowed by the Wiring Regulations to install any concealed cables, except via some pretty unlikely methods.

Though you could argue that if someone is skilled enough to be doing the work they are also skilled enough to avoid drilling through cables in safe zones and therefore if someone is working on thier own house the installation must be under control of a skilled or instructed person.

 

[ban-all-sheds]

But what if they believe themselves to be skilled, when in reality they are a numpty?

 

[kevt296]

If the circuit does not have RCD protection you are not allowed by the Wiring Regulations to install any concealed cables, except via some pretty unlikely methods.

http://www.theiet.org/publishing/wiring-regulations/mag/2008/27-cablesinwall.cfm?type=pdf

Compliance with the Wiring Regulations is not in itself compulsory, but what is compulsory is for you to make reasonable provision in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury, and in reality, practical terms etc, you might struggle to show that you had done that if you had contravened a very safety-related provision of the Wiring Regulations.

Thanks for the information but how is this any different to the fact that all the existing sockets and lighting circuits are buried in the walls, probably less than 50mm deep as part of the original build of the house? The CU fitted was also fitted at the time. Is there a compulsory requirement to change the CU to latest version RCD CU? If so, when was this issued?

I am not asking to have anything installed that is out of the normal or that
would be electrically unsafe or in any way compromise safety, other than asking about having a fused spur cable buried horizontally rather than vertically, which I already believed is permitted.

In respect of the FCU, it is rated at 20A although I appreciate that it has a 13A fuse fitted to it, as does the fuse in the plug for the fire itself.


Finally Mr. "ban-all sheds", is this remark aimed at me?? If so, that is totally out of order. For info, I am a fully qualified, apprentice trained engineer with over 25 years of electrical and mechanical engineering experience and in my time have dealt with 3 phase 440V and single phase 220V and 115V commercial systems. I may not be qualified on domestics or Part P, hence my original posting, however, I have achieved a reasonable understanding of domestic electrics over the past as many year.
Also, I did not say I would be doing the work !! I just asked for feedback on the practice of horizontal cable runs in order to determine what best is needed.

I assume you believe yourself to be skilled? When in reality perhaps you are a numpty? Let's stick to the subject rather than mud slinging. Perhaps we can compare quals one day?

 

[securespark]

He does a lot of (IMO unneccesary) mudslinging.

 

[plugwash]

Thanks for the information but how is this any different to the fact that all the existing sockets and lighting circuits are buried in the walls, probably less than 50mm deep as part of the original build of the house? The CU fitted was also fitted at the time. Is there a compulsory requirement to change the CU to latest version RCD CU? If so, when was this issued?

Your house was presumablly wired some time ago hopefully to the then-current version of BS7671. Standards have changed over time and now concealed cables are generally required to be RCD protected. Exceptions include cables in an installation under the supervision of a "skilled or instructed person", cables protected by properly earthed metal conduit (capping doesn't count because it can't really be reliablly earthed), cables with a built in earthed metal layer (e.g. MICC and flexishield), cables burried more than 50mm deep (but in practice putting cables that deep will cause you to run into other problems like maximum safe depth of chases in walls)

BTW socket outlets "for general use" and rated at less than 20A are also required to be RCD protected under the current version of BS7671.

Now as BAS says there is no explicit requirement in law to work to the current version of BS7671 (or even to work to BS7671 at all) but if you don't then in the unlikely event that your electrical installation was to kill someone or burn the house down you could end up in court having to explain why working to lower standards than those generally accepted was "reasonable".

Most electricians work on the basis that any new work should comply to the current version of BS7671 and as such belive that if an addition is made to an existing circuit that would require RCD protection under the current version of BS7671 then RCD protection for those additions should be provided either by adding RCD protection to the whole circuit or by providing RCD protection at the point where new meets old (see prenticeboyofderry's suggestion of using a RCD FCU).

 

[kevt296]

Thanks for the information but how is this any different to the fact that all the existing sockets and lighting circuits are buried in the walls, probably less than 50mm deep as part of the original build of the house? The CU fitted was also fitted at the time. Is there a compulsory requirement to change the CU to latest version RCD CU? If so, when was this issued?

Your house was presumablly wired some time ago hopefully to the then-current version of BS7671. Standards have changed over time and now concealed cables are generally required to be RCD protected. Exceptions include cables in an installation under the supervision of a "skilled or instructed person", cables protected by properly earthed metal conduit (capping doesn't count because it can't really be reliablly earthed), cables with a built in earthed metal layer (e.g. MICC and flexishield), cables burried more than 50mm deep (but in practice putting cables that deep will cause you to run into other problems like maximum safe depth of chases in walls)

BTW socket outlets "for general use" and rated at less than 20A are also required to be RCD protected under the current version of BS7671.

Now as BAS says there is no explicit requirement in law to work to the current version of BS7671 (or even to work to BS7671 at all) but if you don't then in the unlikely event that your electrical installation was to kill someone or burn the house down you could end up in court having to explain why working to lower standards than those generally accepted was "reasonable".

Most electricians work on the basis that any new work should comply to the current version of BS7671 and as such belive that if an addition is made to an existing circuit that would require RCD protection under the current version of BS7671 then RCD protection for those additions should be provided either by adding RCD protection to the whole circuit or by providing RCD protection at the point where new meets old (see prenticeboyofderry's suggestion of using a RCD FCU).

Thanks for this, great and useful information (Mr. ban-all-sheds take note!). Ultimately, we will have to invest in getting our CU replaced! Any ideas on nominal cost? Currently we have a 6 way CU situated in the garage.

 

[Taylortwocities]

Any ideas on nominal cost? Currently we have a 6 way CU situated in the garage.

About the same as a weekend away.

Cost will depend on the weekend. The same with a CU change.
Get quotes from three registered electricians. Find local ones at http://www.electricsaferegister.co.uk

 

[Taylortwocities]

Though you could argue that if someone is skilled enough to be doing the work they are also skilled enough to avoid drilling through cables in safe zones and therefore if someone is working on thier own house the installation must be under control of a skilled or instructed person.

Yes, that's true. Until the house is sold. electrical installations can last more than 50 years and future generations may not be "skilled" or "instructed".

 

[EFLImpudence]

If the circuit does not have RCD protection you are not allowed by the Wiring Regulations to install any concealed cables, except via some pretty unlikely methods.

Though you could argue that if someone is skilled enough to be doing the work they are also skilled enough to avoid drilling through cables in safe zones and therefore if someone is working on thier own house the installation must be under control of a skilled or instructed person.

Rubbish. That would include anyone.

How does 'someone skilled enough' include those not knowing the requirements relating to the work?