Capping on lighting cable

[johnans]

Do I need to put pvc capping over a light wire running vertically down the wall from ceiling to the light switch I'm installing?
Or can I plaster straight ontop of the twin and earth cable?

 

[GaryMo]

Yes, you can plaster directly over the clipped cable.

I prefer to use PVC capping but it's merely a preference.

Is the lighting circuit protected by a 30mA RCD?
If not, what depth is the cable from the surface of the plaster?

 

[ban-all-sheds]

I prefer to use PVC capping but it's merely a preference.

Even better use oval conduit in case you ever want to add a 2-way switch, or make it a 2-gang to support another light.

 

[GaryMo]

I find that most of the time the plaster is only deep enough to allow a length of PVC capping to sit just under the finished plasterwork, never mind a length of oval capping!

I doubt I'm going to start chasing away at brickwork in the event that the chase may be needed sometime in the future.

Still, where it's possible it could be a good idea for others.

 

[johnans]

My Consumer Unit Has a 5 Amp Circuit Breaker for the downstairs lights, 5 Amp cb for Upstairs lighting.
with a separate Earth leakage Circuit breaker rated at 100mA.
I'm not sure now what I have to do with this wire down the wall.

Thank you all for your Replies

 

[GaryMo]

Have you got a photograph of your consumer unit which you can upload?

Are you sure it's rated at 100mA and not 100A?

Does it say 30mA or 0.03A anywhere on the RCD / ELCB?

When you switch off the RCD / ELCB does this also isolate the lighting circuit which you're about to work on?

 

[johnans]

Sorry I cannot Download Pic. will Describe what I have on CU

Working from Left to Right

6 MCBs 32A, 5A, 5A 16A 45A

Up Sockets, Up Lights, Dn lights, Alarm, Water Heater, Cooker

Next ELCB Label reads Earth Leakage Circuit Breaker Controling L.H Ways Only
Lower Label Reads In = 80A, IoAn = 100ma, Un = 240v

Next is A MCB Combination 32A - 30mA protecting the Down Sockets

And final The Main Isolater Switch[/list]

 

[johnans]

ELCB is protecting all the wiring circuits in house
Pressed test button lights and sockets disconnected

 

[bongos]

Next ELCB Label reads Earth Leakage Circuit Breaker Controling L.H Ways Only
Lower Label Reads In = 80A, IoAn = 100ma, Un = 240v

Sounds like your RCD (or ELCB as it used to be called) is of the 100mA variety.

You will require 30mA RCD protection.

 

[sparkmanc]

pvc capping is really only to protect the cable from damage when your plastering over the chase - so its up to you how much faith you have in your plasterer - them trowels can be sharp!

 

[johnans]

This 30ma Rcd should this have already been fitted, or have the regulations changed since this house was rewired ( Previous Owners )
There is no room for a Rcd in CU is it necessary for me to fit this onto the lighting circuit, everything is working fine.

Has for plastering I will be running the cable down the wall and plastering over, can reaasure you I'm very careful with this type of job.
Can I get away with not having to wire in a RCD

 

[GaryMo]

Twin and earth cable, buried at a depth of less than 50mm from the surface of the plaster requires additional protection.

One way would be to protect the circuit by a 30mA RCD, other examples would be to run the cable through earthed metalic conduit, bury the cable at a depth greater than 50mm or use flexishield cable.

You mention 'Next is A MCB Combination 32A - 30mA protecting the Down Sockets'. This sounds like an RCBO (does it have a little button which trips the device once pressed?). If so then you could fit a 6A RCBO in place of the current protective device for the lighting circuit which would give you 30mA RCD protection.

A photo of your consumer unit would really help.

 

[johnans]

Can you answer me why? has it stands now staus quo (Whatever you Want) I have MCB and ELcb protecting my light circuits its perfectly acceptable. and working
If I change the lighting cicuit ie - move an existing light switch, I have to have a RCD wired into the circuit because I running a new wire down another wall, cannot figure this out.

I'll try to get a Picture downloaded so you can see CU

 

[GaryMo]

Because all new installation work and additions or alterations to existing installations should conform to BS7671:2008.

One of the major changes between the outdated 16th edition and current 17th edition is additional protection in the form of a 30mA RCD for certain cables buried at a depth of less than 50mm from the surface.

What I typed above would aid compliance and an *upload* of an photo of your CU would be handy to help you further.

 

[johnans]

Thank you, Now I understand Regulations have changed

Consumer Unit P2

• johnans
• 12 Dec 2009
• 1

Consumer Unit P2

• johnans
• 12 Dec 2009
• 1