clarify 17th please

[panny300]

been reading the threads on the 17th edition regs,bit confused.
if you add or move a couple of sockets in a room,or add a light switch,and the consumer is the old wylex rewireable.
if the cables are run in the correct zones do they have to be rcd protected or be run in the metal coduit/trunking that everyone is mentioning.thanks

 

[GaryMo]

You have to comply with any one of five options from 522.6.6 if cables are going to be concealed in walls or partitions at a depth of less than 50mm

(i) Cable with earthed metallic covering.....
(ii) Enclosed in earthed conduit.....
(iii) Enclosed in earthed trunking.....
(iv) mechanically protected against damage......
(v) Installed in safe zones.....

Now where 522.6.6 (above) applies and the installation is not intended to be under the supervision of a skilled or instructed person, a cable installed in accordance with 522.6.6(v) and not complying with 522.6.6 (i), (ii), (iii) or (iv) shall be provided with additional protection by means of an RCD having the characteristics specified in Regulation 415.1.1.

 

[Lectrician]

If you added or moved a socket under the 16th would you have added RCD Protection? Most would have.

What I do not want to see lots of, but have unfortunately already seen once, and heard toooo many so called sparks in wholesalers talking about is putting a single 30mA RCD Protecting a whole installation.


When you say to them "you cant", they always come back with "why make the boards then? Im not putting in a 14 way dual split board for 4 circuits". To which my reply is "RCBO's"!

4 x RCBO's and 4 or 6 way straight board is going to cost the same as a dual split with 4 MCB's.

 

[comms]

What I do not want to see lots of, but have unfortunately already seen once, and heard toooo many so called sparks in wholesalers talking about is putting a single 30mA RCD Protecting a whole installation.


When you say to them "you cant", they always come back with "why make the boards then? Im not putting in a 14 way dual split board for 4 circuits". To which my reply is "RCBO's"!

4 x RCBO's and 4 or 6 way straight board is going to cost the same as a dual split with 4 MCB's.

The single 30mA rcd at the head of a cu just to get round one section of the regs, is becomming a common occurance here as well Lectrician.
What these so called sparks fail to realise is, they are actually now not conforming with another regulation 314.2
trip the rcd all circuits are down,,,,,,,,,common sense seems to have left the building with the introduction of 17th, people seem to be panicing, & for the life of me I cant see why, not a great deal has changed in the domestic world except that lights now require rcd cover.
RCBO's are the way forward, or do as you would have done a week ago put a rcd in an enclosure next to the cu for the circuit you are working on if it's minor works.

 

[mattylad]

Why will 1 RCD no longer do when it was OK before?
Whats changed?

 

[panny300]

thanks for the replys,
(1) so if the installation is not under the supervision of a competent person,running a cable down to a socket/light switch in a safe zone is no longer acceptable,unless protected.
(2) how will you bury conduit in a plaster and brick wall,
(3)earthed metal covering,is this capping, i thought i had read somewhere that metal capping is'nt acceptable,or is it because it's earthed,how do you earth it,
(4) the rcd at the side of the consumer unit thats mentioned,does that mean taking the ring cable out of the fuse,putting them into the rcd and connecting the rcd to the fuse with a length of 6mm cable?
sorry for all the questions just trying to get my head round it all.

 

[luminaire]

thanks for the replys,
(1) so if the installation is not under the supervision of a competent person,running a cable down to a socket/light switch in a safe zone is no longer acceptable,unless protected.
(2) how will you bury conduit in a plaster and brick wall,
(3)earthed metal covering,is this capping, i thought i had read somewhere that metal capping is'nt acceptable,or is it because it's earthed,how do you earth it,
(4) the rcd at the side of the consumer unit thats mentioned,does that mean taking the ring cable out of the fuse,putting them into the rcd and connecting the rcd to the fuse with a length of 6mm cable?
sorry for all the questions just trying to get my head round it all.

(1) Correct it must be RCD protected.

(2) As long as it is RCD protected you can use capping; most will still
use plastic capping, as it doesn't have to be earthed.

(3) Steel conduit can be used because it has mechanical protection and therefore doesn't have to be RCD protected. But it it still needs to be earthed.

(4) sorry don't understand your question

 

[Taylortwocities]

Why will 1 RCD no longer do when it was OK before?
Whats changed?

One RCD covering all circuits has never been acceptable.
It is a single point of failure. We've all seen it done - as a cheap and irresponsible way of getting round the previous regs.
It is just as unacceptable now.

 

[dannyboi2003]

Why will 1 RCD no longer do when it was OK before?
Whats changed?

Under the 16th it wasn't ok so the 17th hasn't changed the one rcd for all scenario, i'll let one of the more knowledgeable guys reply in more detail.

 

[dannyboi2003]

Why will 1 RCD no longer do when it was OK before?
Whats changed?

One RCD covering all circuits has never been acceptable.
It is a single point of failure. We've all seen it done - as a cheap and irresponsible way of getting round the previous regs.
It is just as unacceptable now.

You got there before me TTW

 

[comms]

(4) the rcd at the side of the consumer unit thats mentioned,does that mean taking the ring cable out of the fuse,putting them into the rcd and connecting the rcd to the fuse with a length of 6mm cable?
sorry for all the questions just trying to get my head round it all.

Indeed so & this method has been used on many an occation prior to the 17th when extending rings into conservatories.

 

[mattylad]

What do you mean "its a single point of failure" ?

Surely if the RCD fails its designed to go open when it does, making the subsequent circuits safe?

 

[Cremeegg]

Subsequent circuits may be safe but you may not be stuck in the dark up a ladder.

 

[mattylad]

ah, penny is dropping now, is this because lighting should now be behind an RCD?

 

[GaryMo]

Would you want one faulty circuit isolating the whole installation? Think older person late at night.