RCD . Recommendations on testing ??

[burntwire]

I am quoting for a job to fit a new cooker cicuit into a kitchen, There is no RCD protection to any of the house, The man living there is an old chap who cannot afford a new board (the board is fairly modern/good condition with mcbs) now under 17th edition the circuit I am fitting should be rcd protected I will try and locate an rcbo if poss, if not should I fit an rcd into the main tails (is this the cheapest option ?) as this will rcd the whole house -( nusiance tripping !! )or can I simply recommend a fuse board upgrade on my test certificate ?

 

[Spark123]

An RCD in the tails will leave you in violation of regulation 314 for nuisance tripping.
The circuit you are installing should be to the 17th edition, hence
if unprotected concealled cables in the zones less than 50mm you will need some sort of RCD, either an RCBO or an RCCB after the CU. If the CCU incorporates a socket then you'll need an RCD regardless of how the cable is installed.
You can make comments on your EIC about the existing installation.

 

[sparkyspike]

You can get RCBOs for about £22, depending on the make, some are cheaper, others more expensive. This will be the cheapest option, and quite insignificant compared to the cost of fitting and the other materials.

 

[burntwire]

The board is an old proteus type and im pretty sure no rcbo's are availiable for these, there will be no socket on the ccu, personally I think channeling out 50mm deep in any wall must affect the strength of the wall ?.
I think I will need to fit a small rccb board next to the existing board which will mean henley blocks and tail upgrade to the existing board, its not a problem but it does seem like a lot of work for 3 metres of cable !

I understand that the 17th are pushing us towards rcd's - which is a good thing but it can create problems and customers will probably not have work done due to the extra costs involved or get someone who's willing to cut corners for a quick buck !!

Just out of curiosity are the grants availiable to pensioners to ensure their houses are safe or to help towards the cost of making them safe ?

 

[GaryMo]

If you go for the option of a second board with RCD protection then don't forget to install a main isolator for single point of isolation if there isn't already one there.
If there's a spare way on the existing board then why not fit a 32A MCB, wire to an 2 module enclosure housing a 30mA RCD then off to the cooker circuit?
It's probably going to be the cheapest option.

 

[sparkyspike]

You can get Proteus RCBOs (or M2 replacements) at City Electrical Factors. Single or double module.

 

[Pensdown]

As long as the CCU does not have a socket outlet to meet the 17th all you need to do is put the drop to the CCU in steel conduit, or I'm I missing something?

 

[ericmark]

Use cable to BS 8436 and no need to fit RCD is this not easy way out? i.e. Flexishield there is nothing in BS 7671:2008 that says you need a RCD for a cooker unless the cooker manufacturers recommend one. Next is garage or bathroom consumer unit next to main one which would include an RCD.
With cookers using mineral insulated elements BS 8436 cable may be best anyway most is also to FP200 as well.
Eric

 

[sparkyspike]

Why spend more on cable, when you can just fit an RCBO? Flexishield complies with 2008; not sure if FP200 does, think FP400 does.

 

[ban-all-sheds]

And here we see what happens when you let engineers write regulations when they are either too ignorant to have heard of cost-benefit analyses, or so professionally negligent that they don't think they have a duty to carry one out.

 

[NotHimAgain]

Whilst Flexshield can provide an answer, you should be aware of its limited short circuit performance.

You need to check the specification but, as a statement on their web site indicates, it should not normally be used on circuits with a prospective fault current that exceeds 170A, and they further recommend that the mcb should be no larger than 32A Type B.

 

[NotHimAgain]

And here we see what happens when you let engineers write regulations when they are either too ignorant to have heard of cost-benefit analyses, or so professionally negligent that they don't think they have a duty to carry one out.

I suggest you read page 2 of BS 7671 BAS.

Once you get past this-

While the publisher and contributors believe that the information and guidance given in this work is correct, all parties must rely upon their own skill and judgement when making use of it. Neither the publisher nor any contributor assume any liability to anyone for any loss or damage caused by any error or omission in the work, whether such error or omission is the result of negligence or any other cause. Any and all such liability is disclaimed.

Oh look a disclaimer - its actually an almost word for word mirror of the ones in the OSG, GN7, GN8 and Paul Cook's Commentary .

You will also find this -

It is the constant aim of the IET and BSI to improve the quality of our products and services. We should be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary, G D Cronshaw ([email protected]), The IET, Six Hills Way, STEVENAGE, SG1 2AY, UK.

Seems they want public spirited citizens to help them out.

With regard to your comments here - it depends what sort of a European you are BAS. You see our ignorant engineers have been delaying the implementation of 415.1.1, which is behind 522.6.7, since 1982 when it first appeared in an IEC document - almost word for word. Now since they were charged with harmonising BS 7671 their hands were somewhat tied.

However, the application in 522.6.7 should be critisised - so I refer you to their request for help - I am sure they would appreciate any constructive comments on this and any other concerns you may have.