consumer unit change

[Naz]

hi all,

can u suggest best way forward, changing out an old wylex fuse box to new split load board, the premises has 40+ old wiring, red and black conductors, the lighting circuits are 2 core with no cpc cable. Under current regs do I need to rewire the property or can i connect original wiring to the new board bearing in mind that I am improving the situation with new breakers and rcd's.

regards

 

[DurhamSparky]

in regards to the No CPC on the lighting circuit download and read the best practice guide

http://www.elecsa.co.uk/downloads/p...Circuits with no Protective Conductor_ESC.pdf

all is explained in this guide..

for changing the CU that is straight forward and easy to do if you have the understanding knowledge, may i ask if your Part P registered or intending to notify LABC on this matter as this Job is a Notifiable work and if not followed correctly can lead you to a court appearance and fine of up to £5k

when you say the wiring is 40+ im assuming you mean years? if so it would be a good idea to start off with a few simple tests on the installation or failing that undertake a full PIR as this will ascertain the current condition.

Yes it may be easier to rewire that to just upgrade as you will only have a few years left on its "shelf life"

 

[Sav]

Hi Naz,

Me personally would rewire the place to be safe. 40+ year old wiring sounds veru fragile.
with regards to the no cpc in the lights, you need to address this by having only class 2 fittings (plastic, nothing metallic) and fit warning notice on consumer unit.

To be on the safe side, do a test on the existing wiring beforehand, as this sounds like a can of worms !!!

Good luck either way mate,
Sav

 

[nickblake]

No cpc's possible getting on for 50 years old ,any VIR's there , all i can recomend is to check the neutrals when you have to old CDU off and confirm you have no shared neutrals etc , check the guidance for lighting with no cpc's as been mentioned by what you have said though may require rewiring

 

[mnmwill]

I had a similar situation recently, no cpc on lights, old ceramic fuses, no earth to gas/water. Sockets added randomly to JB's under the floorboards. House was built around 1965/70 and no improvements to circuits since....

Recommended complete rewire, as Sav said its a can of worms, best of to just rip it all out and start again im my opinion.

 

[Naz]

hi all,

thanks a mill for the advice, the property is a small 2 up 2 down, 1960-70's, good advice about pre tests, will do continuities and ins resis on all conductors to ascertain integrity.

I am Part P and 17th qualified and intend to offer this cu change as one of my evidence jobs.

I ve looked through regs etc looks like if wiring is 'safe' then one can connect new wiring via effective crimping but a label stating different colours needs to be placed by cu.

As far as no cpc's on lighting -would you suggest that the rcd in the new cu would provide protection and that all the light fittings and switch's are in pvc would give a good measure of local protection.

regards

 

[claret73]

With no CPC in your lighting circuits, an RCD would not provide additional protection due to disconnection of Live-Earth faults. Would you not, only be providing overload protection by the MCB's for these circuits. Best to look at the ECA Guidance note on this as said, as I'm thinking with upgrading the CU to 17th edition whereby we should be providing discrimination of circuits, you'd be looking at looping in a CPC to all light & switch fittings...plus the potential of borrowed Neutrals, as has been said.

Maybe rewire all lighting points?

There is a Sticky by Jason I think on pre Installation guidance for CU Changeovers...

 

[Naz]

thanks all,

have downloaded guidance as suggested, am reading through and getting some idea. There are some shared neutrals which i can split in a new board, some light switch's are metal so i will need to look at this, the the new cu will be a split load with 2 rcd;s and associated mcb's. I will give serious consideration to rewire the lighting circuits in twin and earth, have to do this with min of disruption and mess and to ensure good split of circuits to minimize inconvenience.

regards

NAz

 

[JulianC]

With no CPC in your lighting circuits, an RCD would not provide additional protection due to disconnection of Live-Earth faults.

An RCD will trip when it detects an imbalance of current between L & N. Presence or otherwise of a cpc is irrelevant. The RCD doesn't care if the fault current is flowing down a green and yellow stripey wire or through your body, so in this respect an RCD will afford additional protection to a lighting circuit without cpc. As I understand it though, as long as you have class II fittings and accessories fitted throughout and a warning notice on the CCU, there is no absolute requirement to rewire the lighting circuit.

 

[claret73]

In finest Homer Simpson...

DOH!

My mind was elsewhwere & simce found a link ti the IET where such a discussion raged on...

Aplogies to Naz, checked back to OSG, corrected myself

 

[Naz]

thanks all,

yep had thought about that, ie rcd and double insulated fittings, think easiest thing will be to pull new twin and earth along existing ceiling cavities and connect up properly to cu. Gona be messy and more work but at least will hopefully meet requirements of regs.

cheers

Naz