17th Ed Consumer Unit - enclosure only?

[Jimbo]

Hi,

I have a 16th Ed. CU which I'd like to convert to a 2-RCD system. Problem is that it only has two Neutral terminal blocks.

I've been looking at empty enclosures on Screwfix but it's not clear from the listings whether they have the three Neutral blocks required for incomer + 2 RCDs.

Can anybody advise? And out of interest, will this update make the CU 17th Ed. compliant?

Thanks
Jim

 

[ban-all-sheds]

1) Are your existing MCBs etc compatible with the CU you plan to buy?

2) I have to advise that asking that Q about 17th Edition compliance does not indicate that you know enough about the Wiring Regulations to be attempting a CU replacement.

 

[Jimbo]

1) That's a good question, I would plan to buy MK, which is my current CU. I assume they'd be compatible?

2) I haven't read them, no. But replacing one screw-terminal box with another isn't something that I consider any more taxing than wiring a plug. The principle is identical. If the house wiring is good, then the house wiring is good. I'll get it checked, I just want an early indicator of my options before I proceed.

I have a healthy respect for electricity, and I'm not stupid! I just want to know whether I need to buy a brand new CU or whether I can update my existing one. It all affects the overall cost.

 

[JohnD]

An alternative might be to fit RCBOs in the non-RCD ways of your existing CU.

MK have slightly altered the design of the MCBs several times since Sentry first came out. There ought to be a compatibilty table somewhere.

 

[ban-all-sheds]

1) That's a good question, I would plan to buy MK, which is my current CU. I assume they'd be compatible?

Not necessarily - designs change.

2) I haven't read them, no.

http://www.amazon.co.uk/Requirement...Regulations/dp/1849192693/ref=pd_bxgy_b_img_b

But replacing one screw-terminal box with another isn't something that I consider any more taxing than wiring a plug. The principle is identical.

• For a circuit to supply a given load, how would you go about deciding what cable and protective device to use? (No, you can't just copy what's there because it's going to become your responsibility and what's there might be wrong.)
  
  
• Do you know which circuits can be ring finals and which cannot, and what the advantages and disadvantages of each are? (No, you can't just copy what's there because it's going to become your responsibility and what's there might be wrong.)
  
  
• How do you calculate maximum demand and how can diversity be used?
  
  
• Can you correctly identify all components and connections of a circuit by method of testing or otherwise? In doing so can you identify or recognise anything wrong or dangerous with the circuit? You cannot assume that what's currently installed is OK, and you need to check it before starting work.
  
  
• Do you understand how the way in which cables are installed affects how much current they can carry? (No, you can't just copy what's there because it's going to become your responsibility and what's there might be wrong.)
  
  
• Where cables need to be joined, how should this be done / not be done and in what circumstances are different methods acceptable?
  
  
• Can you identify extraneous conductive parts, and do you know the requirements for main and supplementary bonding of them?
  
  
• Which circuits should be RCD protected?
  
  
• What about the testing that you should do on your existing installation before you change the CU, if you want to be sure of avoiding grief from new RCDs tripping?
  
  
• And what about the tests you should carry out after the installation? What sequence will you do them in and at what point will you energise the installation, and for each test do you know what is being measured, why it is important, how you would carry out the test, and with what equipment, and what sort of results you would expect to get if everything was OK?
  
  
• How do you propose to isolate the supply so that you can install the CU?
  
  
• Do you believe you are qualified to issue an Electrical Installation Certificate for the replacement?
  
  
• If you are in England or Wales are you aware that you'll need to apply for Building Regulations approval in advance, and as part of that you'll have to say how you'll ensure that your work complies with P1?
  

If the house wiring is good, then the house wiring is good. I'll get it checked,

Do you mean the existing wiring or your work? By whom, when, and to what end?

I have a healthy respect for electricity, and I'm not stupid!

Nobody is saying that you are, but the problem is you have no idea of what's involved in installing a new CU.

I just want to know whether I need to buy a brand new CU or whether I can update my existing one. It all affects the overall cost.

Ask your electrician, because you really need to use one for this job.

 

[securespark]

Wouldn't it be easier and cheaper to replace the MCB's on the incomer side with RCBO's??

Ban's comments still hold validity, though.

 

[SimonH2]

Playing devils advocate, wasn't there a thread not long ago where the consensus was that Schedule 4 allows for an enclosure to be replaced without being notifiable - which is what the OP wants to do.

After changing the enclosure, there was then less clarity on whether swapping an RCBO in place of an RCD was also permitted by Schedule 4.

 

[seasickstevie]

Surely the RCBO would be in place of an MCB.

A couple of RCBOs would be far better than one extra RCD and extra busbar - and a lot less hassle.

 

[PrenticeBoyofDerry]

Can anybody advise?

Put the manufactures RCBO in the non protected side of the consumer unit.

And out of interest, will this update make the CU 17th Ed. compliant?

Probably not, as there has been a few changes in the requirements since the 16th edition, not just RCD protection.
Does not mean that the system is any less safe, just because there are deviations from the 17th Edition.
May I ask why you wish to do this?
Are there safety issues or has someone mentioned upgrading to the 17th edition to you, and you now think you must comply to those requirements?

 

[JohnD]

RCBOs are great!