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Fuse box and rcd protection

About 12 months ago I had a new domestic fuse box installed. This does have a trip switch as an electric shower was fitted at the same time. Recently I have had a new kitchen installed and that required some extra sockets. When their electrician came to sign off the job he said that I had no RCD protection and that the 'tails' were smaller than they should be. I went back to my original electrician and explained all this who says that given that I only have a 2 bedroom house that the tails are quite sufficient - 16mll instead of 25 and earth 10ml instead of 16ml. Is this a fact? I don't want to have to spend out another lot of money if what I have is more that up to standard.

3 Answers from MyBuilder Electricians

Best Answer

First and foremost did the electrician that fitted the new fusebox 12 months ago, issue you with an Electrical Installation Certificate (EIC) for the work and did he register the completed job with the local authority building control? - (If he did you should have some paperwork to this effect) If you don't have both of these then that is an issue as part P of the building regulation has not been complied with.

With regard to the new fusebox that was fitted. If it only has Miniature Circuit Breakers (trip switches) for each circuit and no RCD protection then the electrician who carried out the work 12 months ago, did not install the correct type of fusebox that meets the 2008 regulations. Since 1st July 2008 all consumer units should be of the high integrity dual RCD and MCB type. Such that all circuits in the house are RCD protected to maximise user safety.

Finally on the last point with regard to the 16mm meter tails, technically if the house is small and the main fuse located inside the electricity suppliers cut-out is 60 amps, then 16mm tails are fine. If there is a 100amp fuse fitted then it should be 25mm tails and a 16mm earth. Details of the cut-out fuse are sometimes printed on the fuse carrier itself, but should also be on the electrical installation certificate for the fusebox (provided you were issued with one that is).

In summary, the new sockets that have fitted must have RCD protection and the kitchen fitter or second electrician should have fitted an RCD if you did not already have one and issued a second certificate for the extra sockets. This guy sounds like he knows his stuff and is more up to date with the regulations than your first electrician.

Hope this helps.


Answered 23rd Nov 2011

In most cases a single question asked to 10 Electrician will result in 10 different answers. In most cases common sense can be used to resolve most conundrums regardless of regulation.
If you are not rewiring the house from new and it only an upgrade. this don't need to comply with the latest 17th Edition.
The idea that you will need to have a dual RCD consumer unit for all circuit and that every circuit needs to be RCD protected is not also correct and no regulation says that. However all outside sockets needs to be RCD protected. Shower unit looking at manufactures instruction will also need RCD protection.

If you have an old pensioner staying in a flat with only one light circuit which you see in many flats - only a fool will install Dual RCD and put the only one light circuit on RCD. Don't forget there are also split load consumer unit with RCBOs options. Stand alone appliances with one circuit dedicated to them don't have to be RCD protected. So pls read the 17th Edition carefully before making a generalised statement. More common sense will safe customers money and time and hassle on unnecessery work.

In regards to your work, you can get RCBO to cover the kitchen socket - you don't have to change the whole fuseboard.

pls let us know how it went. Michael Esin - CIVIL Electrical Services -


Answered 28th Nov 2011

all circuits buried in a wall at a depth less than 50mm must be RCD protected unless they are enclosed in metal conduit. So every circuit in your property should be RCD protected.


Answered 23rd Nov 2011

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