Replacing consumer unit - need junction box (SCOTLAND)

[Gees]

What happens if you have a fire ? Will you claim all the certificates where lost in the inferno?

BAS can be pompous but sometimes talks sense.

 

[ban-all-sheds]

All seperate circuits will have their own MCB and 6 of the MCBs will be fed from the on-board RCD. I may remove the single RCD and replace all MCBs with RCBOs later on.

If you want to comply with the Wiring Regulations you have to replace them now - it is almost impossible to avoid needing RCD protection on circuits with concealed cables.

Without wishing to be rude, I am dubious as to the requirements for a full review of the existing wiring and installation methods within the house.

Given that the CU I am using will replace all the fuses with like for like MCBs, there will not be any change in the operating conditions for the existing wiring under fault or non-fault conditions so I think I am happy to go ahead.

By replacing the CU you are making design decisions about the ratings of the MCBs. If the existing devices are wrong then you will be wrong, and contravening the Wiring Regulations, if you just assume they are right.

After all, if I were not about to be replacing the consumer unit, would you still recommend I carry out all the tests that you describe? In that case, are you recommend some form of periodc check?

That might be advisable, but the real point is that if you are going to replace the CU then the responsible and competent thing to do is to check that all is well with the existing installation.

Also, remember that whether you need a warrant or not, you are still bound by this:

Electrical safety
4.5 Every building must be designed and constructed in such a way that the electrical installation does not-

(a) threaten the health and safety of the people in, and around, the building; and

(b) become a source of fire.

If you make changes you're no longer just the innocent inheritor of someone else's work. Not one expert would ever say that you need no special knowledge or skills to competently replace a CU, so the reasonable assumption would be that you have assumed some responsibility for the installation by taking on a major job like that.

If you do not do what is widely regarded as good practice then you could be judged to have been careless or negligent.

As for the electrical installation certificate, I am yet to find any piece of legislation that states that I require one. That is not to say that I won't have it checked by a certified electricion later on but I'm still curious as to whether this is actually necessary.

Explicitly and legally? No, it's not.

If someone were to say to you "You replaced that CU. Can you prove that you did it properly?", what then?

 

[baldelectrician]

This is an intersting thread

Wylex would not be my first brand I would choose (especially for my own house)

As far as certification goes, it's all up to you. You may (but probably won't) be asked to have the wiring checked if you sell (the Home Report is staying in Scotland, but HIP's are going elsewhere)

The only pitfalls are ;
Your insurance company may not pay out if something bad was to happen (there are clauses about certification)

The place will not be tested fully (I am assuming you don't have a earth loop impedance meter ot insulation tester), so could be unsafe

 

[skenk]

Yeah i'll second that, your insurance will likely be invalid if your house burns down due to an electrical fault after you have done a DIY CU change, also you may have problems selling if the buyer finds out about it (if they ask you are legally obliged to tell . . .).

Also you may (very well IME) have an existing fault which would not be detected by fusewire but would not allow the RCD to stay 'on' after connection. You will need to make sure all your tests are done before you start. For experienced electricians the CU change is the 'easy bit' it's the testing and sorting out all the problems found by the testing that takes time.

 

[martinxxxxxx]

Personally I would get the PIR done before doing anything else. As this will give you a sure foundation on which to start the the job. While the electrician is there, be sure to ask him how much he would charge you for a consumer unit change, you might be pleasantly surprised, because once he has done the the PIR he will know just how easy the new unit will be to have be fitted. If there are lots of remedial items to clear up. Then it would be better to have them done before fitting a new cu.Because as the poster before me has stated, the new board won't work with some of the faults that the current one will do.

Martin

 

[iep]

Thanks again for all the useful info. I'll try to address the points below:

Rebuke. My plan is to use the RCD'd portion of the box with the following six MCBs:

1. Kitchen Ring 32A
2. House Ring 32A
3. Garage non-ring 16A
4. Porch non-ring 15A
5. Bathroom shaver socket 15A
6. Loft Sockets non-ring 15A

Non RCD'd MCBs
1. Living area lighting
2. Bedrooms lighting
3. Doorbell transformer
4. Garage Lighting

The doorbell transformer and garage lighting cables are run on the surface of the garage walls (non buried).

The lighting circuits run primarily through the loft space and then drop down to the sockets. They are all run within stud walls which are 12cm thick. Given that the cables are technically 5.5cm deep within these wall I don't know what regs would apply. However, it would be very cheap to buy 2 RCBOs to replace the two lighting MCBs and that would (if I understand correctly) remove any doubts.

Baldelectrician: I have access to an earth loop tester so will use that to check the protection on the mains sockets.

As regards the insurance issue, I am curious how this would be enforced. The CU I plan to use has been available for several years. I bought the house this year. In the unlikely event that something were to go wrong, what is to stop me saying that the consumer unit was there when we moved in and that we did not recieve a certificate when we bought the house?

Besides this, I am a competent and cautious person who reserches all of his work extremely carefully befiore carrying out the task. My feeling is that I will do a more thorough job tham most tradespeople (this has always been the case in the past). No offence, but I am yet to employ any tradesperson who has ever done the job correctly without me calling them back to correct the errors in their work. After all, who cares more about my house and my safety than me?

Cheers,

iep.

 

[Gees]

Will it not be a bit dark in the bathroom at night

 

[iep]

Sharp observation! Bathroom light runs on the garage lighting circuit.

iep

 

[MalcofArabia]

Looks like your going to have to get them RCBO's then

 

[iep]

If that is best practice then I'll definitely take your advice on the RCBOs. I only need two to cover the concealed lighting cirucits so It's not a great expense. Good tip. Thanks.

iep

 

[iep]

Can anyone tell me what the difference is between a b-curve and a c-curve rcbo?

I guess that these are the type b and type c variants I have seen for sale?

ip

edit: think I just found the info. Based on expected surge currents, type b (or b curve) is the recommened variant for domestic application.

 

[ban-all-sheds]

//www.diynot.com/wiki/electrics:mcb2

 

[iep]

tremendously useful link. Type_B it is.

ip

 

[Gees]

I would have ran the shaver socket from the lighting circuit and the doorbell from a FCU on the nearest ring? ( and fitted RCBO's on the whole lot and to heck with the expense )

A seperate radial feed for your fridge / freezer can be a good idea also

 

[iep]

Hi Gees,
The Freezer, washing machine and tumble drier are all in the garage (where all cables are easily accessible) so I intend either to upgrade the garage radial feed to a full ring or provide a dedicated radial feed for these appliances (or maybe both).

BTW, what is an FCU?

I'm not sure why the shaver socket gets its own decicated radial feed from the fuse box but I don't see any reason to change it at this point?

Cheers,

ip