Extended ring main

[Joe Shmoe]

Hi, just put an extra 3 sockets around my house (not spurs).

Would an electrician now test it using something?

Everything is working fine obviously, but just wondered if they do anything for safety/double check etc?



Cheers

 

[carlb40]

They will do various tests, depending on the install/ location etc. One is a continuity test. Possibly an earth leakage test. Someone with better knowledge may help further. My knowledge is just from working along side sparks on various NHS contracts

 

[OLD]

Most important is to check that the correct size cable has been used and wired correctly. metal boxes etc connected to earth and sleaved , check regulations for floor area of modified ring.Are the things that spring to mind.

 

[Dee J]

Assuming that the original installation is ok, with correct conductor sizes and appropriate equipotential bonding... and that your new wires are the right size and correctly installed by correct methods in the approved zones...
Some guidance on tests...

With the power off

Continuity of each conductor in the ring. (measured values r1, r2, rn)
Insulation resistance between all conductors in the ring
Check that the ring is a true ring... not a figure 8
Worst case cpc resistance (R2) or combined line+cpc (R1+R2)

With power on

Earth fault loop impedance at source Ze
Tripping times of RCD (at x1 and x5 tripping current)
Earth fault loop impedance of whole circuit Zs (and is this within the permitted values for the circuit protective device)

That's pretty much it, but remember TNC-S and TT supplies use different approaches to earth-fault tripping and Zs values.

Dee

 

[Racers]

Hi, Joe

You can fit as many sockets as you want, you just can't connect them to the existing ones unless you are Part P registered.

Pete

 

[Lons]

Hi, Joe

You can fit as many sockets as you want, you just can't connect them to the existing ones unless you are Part P registered.

Pete

Are you 100% sure about that Pete?

Whilst I don't advise the OP to do so, it's my belief that the work is non notifiable and can be self certified by a competant person as long as the additional sockets are not in a "special area" such as kitchen, bathroom or outside. and is just an extension to the existing circuit and not a new installation. This is also provided the existing circuit is properly protected and adequate to carry the load.

Whilst the introduction of Part P is for the right reasons, it's a minefield and far from clear. Many of the electricians I come into contact with don't fully understand it and some even exploit it.

The biggest hurdle is definition of a "competant person"

i stand to be corrected of course.

Cheers

Bob

 

[Racers]

My understanding is that you can replace a socket, light switch, piece of damaged cable but not add any thing to the existing instillation.

Pete

 

[Lons]

My understanding is that you can replace a socket, light switch, piece of damaged cable but not add any thing to the existing instillation.

Pete

Hi Pete

As I said, it's a minefield but not my understanding. perhaps a qualified leccy could come in here?

I did the research as well as discussing with the local building inspector when building my extension and whilst I couldn't use it there (special areas) that's the conclusions reached. The BI told me that part P is a mess and a joke BTW :?

I'm just in for lunch and had a very quick look but will research tonight if I get time.

http://www.niceic.com/Uploads/File1247.pdf

here's a quote off the site above for example

Minor work
‘Minor work’ is electrical work that does not involve the addition of a new circuit, for
example adding new sockets or light switches to an existing circuit, or the replacement
of sockets, light switches and ceiling roses. This work does not have to be undertaken
by a registered electrician and you do not need to notify your local building control office.
However, ALL electrical work must comply with BS 7671, the wiring regulations.

As I said though I stand to be corrected as I'm not a qualified electritian!

cheers

Bob

 

[Racers]

Hi, Bob

It does seem like they are trying to prevent poor quality installations, by creating an atmosphere of fear and disinformation.

Pete

 

[RogerS]

Ah Bob...but how do you define 'adding new sockets' as opposed to 'adding a new circuit'. It is poorly drafted. Is a new circuit a spur from an existing socket....? Probably not but breaking into an existing ring and adding extra sockets...is that a 'new' circuit?

 

[Lons]

Ah Bob...but how do you define 'adding new sockets' as opposed to 'adding a new circuit'. It is poorly drafted. Is a new circuit a spur from an existing socket....? Probably not but breaking into an existing ring and adding extra sockets...is that a 'new' circuit?

Hi Roger

From my investigations a couple of years ago, A spur is definately and extension but extending an existing ring circuit by cutting the wire and looping between the cut ends whilst could be construed as new, can also be viewed as just extension of existing. As I said however the circuit must be capable of carrying the additional load.
My BI confirmed that as well but there is no guarantee he knew his stuff as they are a bit generalised in their information.

Confusing which is why part P is a mess and will be changed at some stage. Hopefully it will be much clearer. typical government cock up as usual.

Bob