regs on RCDs - NIC assessment so has to be right...

[blackcurrantbeastie]

Hi All,
I'm working towards NICEIC domestic installer and have two jobs lined up, neither of them straightforward and could do with some advice on a couple of things.
First one is on a minor installation, simple replacement of a damaged pendant in the upstairs lighting. The house is c1970s with TNS supply and has three seperate old style rewirable fuse boxes, one for outbuildings, one for storage heaters and one for the main house. From reading the regs, pretty much everything needs to be protected now by an RCD, and on the basis that I can't see that the lighting circuit wiring is less than 50mm from the surface of the walls/ceiling and I can't see any metal sheathing on it I need to add in some RCD protection. The client does not want me to replace the existing consumer unit due to cost and its only the one circuit I'm altering, so I'm thinking that the cheapest way to provide RCD protection would be to take the feed from the existing fusebox with it's 6A fuse and pass this through a very small (4 way) consumer unit with RCD. Is there an easier/better way?
Second question is on a consumer unit replacement on a TT system. All the tests come up good or marginal other than insulation resistance on the sockets ring main which is a fairly appalling 500K. The client doesn't want me to spend hours tracing the fault, in this situation, do I have to find the fault or do I simply sign off the consumer unit as ok as this is what has changed and note the insulation resistance on the departures section of the cert?

thanks in advance
Matt

 

[disinfo]

How many outlets does the ring main supplying the sockets have?

If its a fairly small installation it shouldn't take that long to find the section of the ring that's causing the problem.

What type of cable has been used for the ring final?

 

[mikhailfaradayski]

for the first part, might i suggest you look again at the regs. and app. doc part P to help you decide what constitutes an alteration or addition and decide from there whether you even need to consider an RCD. I think you may be OTT here.

For the second part, you shouldn't be connecting circuits which are not suitable to be connected, your assesor (i imagine) would take a dim view of that. Although i'm sure the customer doesn't want to spend any money, but it is your competence that will be questioned if it was found that you knowingly connected a circuit which doesn't meet the basic requirements. Be prepared for awkward questions from your assessor if you tell him that you have done this, he may ask you why you didn't either PIR the install before you started or at least give the customer a clear idea that changing a board might uncover other problems which need rectifying.

Welcome to the world of supplying a service to folk want everything for free, yesterday and will still probably moan that you were too expensive

BTW, does changing a simple light fitting really qualify as a job to be assessed upon? Seems just a little too easy

best of luck

 

[electronicsuk]

Why would you need to apply RCD protection when changing a damaged pendant? There's no new wiring involved, unless there's something you haven't mentioned?

In addition to what has already been pointed out regarding reconnection of a circuit with low IR; how do you think the client will feel about the 'favour' you did them by reconnecting it, once the RCD starts tripping twice a day?

 

[securespark]

Must concur with others.

No need to upgrade the installation AT ALL if changing like for like.

And you should not reconnect any circuits that are unsafe, including wiring in rubber cable & those with IR down.

You could split the ring at the board and at one skt, then meg both to see which is faulty. This will narrow down the area of the fault.

 

[1john]

I wouldn't think that an assessor is going to be happy for you showing a pendant replacement as an example of your work.

 

[blackcurrantbeastie]

Thanks all for your replies, most helpful, I'll have to reassess my assessable work!

 

[bongos]

From reading the regs, pretty much everything needs to be protected now by an RCD, and on the basis that I can't see that the lighting circuit wiring is less than 50mm from the surface of the walls/ceiling and I can't see any metal sheathing on it I need to add in some RCD protection.

Safe zones do not apply to cables run above ceilings.

You mention replacing a damaged pendant and having to protect the circuit by an RCD. On this line of thinking you would have to chuck RCD's in for all sorts - cracked light switches, damaged s/o etc...

You need to go and have a good read of the regs and make sure you know when RCD's are required and when they aren't. Also when exceptions can be used and when they can't. It's likely your NICEIC assessor will be asking you lots of questions on your initial assessment and he/she will want to make sure you know your stuff. Also if you tell customers they need an RCD installing everytime they want a light fitting changing then you'll struggle to make any money or be competitive with the next spark who simply changes the fitting!

 

[ban-all-sheds]

You might be able to put "As Seen On TV" on your advertising though...