consumer unit, need earth?

levis2891

hello

i was wondering if new consumer units needed earthing?

our house and our neigbours were built without earth wire (i've been told) but had a fusebox wired so it was safe (sorry i don't know the specifics).

recently we had a new consumer unit fitted (rcd protected, certified, part p etc). today we had someone over to check some wiring (bathroom being fitted and had to check a wire had been removed safely).
anyway, he done that and another check we asked about a light. he said theres no earth, when we had the new consumer unit fitted the earthing should have been done. do we need every light/switch earth wired?
(i've been told that some of the house is earthed but certain older lights arn't, although being that i'm just about qualified to change a plug i personally couldn't comment :lipsrseal)

can a new unit be certified if not all fittings are earthed?
were now worried our home cover isn't fully covered

maninthestreet

If it was just a new consumer unit you had fitted, then the wiring in the house would have been untouched.

levis2891

thanks for you quick response maninthestreet
we had the unit fitted as we needed a new shaver switch, fit additional plugs and changed some light fittings so we decided to upgrade our unit.

so can we continue to safely leave the wiring untouched?

chrislee765

afaik you need an earth. In case of a fault this provides enough current to activate any protective devices.

i've been told that some of the house is earthed but certain older lights arn't

- But you said your consumer unit doesnt have an earth? therefore is the earth thats connected to these fittings actually connected to 'earth'?

I hope someone better comes along soon

levis2891

i think there is earth in the unit as its bonded to the gas, on the report it says
'consumer unit 17th edition but no earth in the lighting circuit, metal light fittings with no cpc'

sorry if i wasn't clearer before, i'm still trying to make sense of it all

Cknocker

From that, it appears the consumer unit is earthed (I would be very surprised if any electrician installed a consumer unit with no earth!) The lighting circuit though is not earthed, this is probably because it has been wired in two core and as such can not be earthed, this leaves the potential for the metal light fittings to become live if there is a fault in the fitting, if that happens and you touch the light fitting you will become the route to earth - not good!

levis2891

the lights do have metal bases so thats not good

so i guess i should get those changed

maninthestreet

Cknocker wrote: »

From that, it appears the consumer unit is earthed (I would be very surprised if any electrician installed a consumer unit with no earth!) The lighting circuit though is not earthed, this is probably because it has been wired in two core and as such can not be earthed, this leaves the potential for the metal light fittings to become live if there is a fault in the fitting, if that happens and you touch the light fitting you will become the route to earth - not good!

Would the RCD protection in the CU prevent electrocution in this case?

AdrianW2

maninthestreet wrote: »

Would the RCD protection in the CU prevent electrocution in this case?

Possibly. A working RCD detects imbalance between the live and neutral, so a live to earth fault would trip it, but a live to neutral via a person wouldn't.

IMHO a RCD is a backup device, the primary protection should be the earth. A RCD is an electromechanical device with inherent points of failure, whereas an earth just is.

levis2891

thats what i thought but the guy from british gas who also covers our electrics was adament that we needed earth in our lights and questioned whether our current cover was valid!!!!

he said that we should get our electrician to come back and sort it out as it isn't up to code. which means chasing walls, ceilings and lifting wood floorboards which will be a huge pain.

i honestly thought that with out new consumer unit everything was safe

Rosebery_2

If your lights are double insulated they don't need a separate "earth". It sounds as though yours aren't in which case you do. It would be simplest to get yourself double insulated lights.

As to the CU. There are different methods of supplying an earth to the property TT, TNS, TCNS for example and they are not the same. If the CU was properly installed and certified to both the 17th and Part P as you say it was it would not be in your electricians interest not to do it properly and he would have done it according to the earthing system in use in your property. He could end up in prison if it was wrong - simple as that. So discussing the CU is, to my mind, a bit of a red herring.

The BG man is probably on about what I talked about in para 1 but hasn't explained it to you properly.

Discussing it on this board is a waste of time for you, frankly. I would contact the electrician who did the CU change and tell him about the BG mans concerns. Let him tell you if there is a problem or not.

Oh and BTW

........he said that we should get our electrician to come back and sort it out as it isn't up to code. which means chasing walls, ceilings and lifting wood floorboards.....

is an example of applying the CYA principal. He's suggesting a rewire but your electrician will be able to tell you if thats correct..

Cheers