Wiring a consumer unit to the mains

[EFLImpudence]

I think we'd best advise that you have an electrician have a look at it all.

 

[Alanallsorts]

Basically, MK has gone a tad down the tubes, their stuff used to be made in London not Malaysia! Nor do they label well, they leave you to do that so you need to know in advance; hence anyone coming new to their consumer units can be confused. However, before they seek help here MK does have a site. Now, anyone not knowing how to wire up an MCB, or what a bus bar is should take my fellow qualified colleagues' advice, please. Unfortunately, it is a swine to line up the MCBs, start from the right and hold tight as you do them, as it is the RH tread that generally skews them. Naturally, with the power off! In any subject, if unsure please leave alone for your own and others' safety. You can learn without forking out oudles at a local college for any vocational courses; strange how the daft ones are free to some and discretionary to others, like left-handed winget knurdling; that would be an intensive course for only £20; whereas even a 17th Regs refresher is £900 for an OAP. You could get paid to learn if you have the aptitude and your maths is good enough to get into REME; not RAF as I spend a lot of time correcting an ex-RAF guy's lethalities! As an ex-BAe instructor I suspect the RAF was having a bad hair period when he trained?
Or go on work experience with a qualified person? Even buy a book, not the IEC's, you'd have first to be a millionaire to afford their stuff? Most of wiring is common sense, that rarest of commodities, but only if you know the basic physics to start with. If you cannot use algebra you won't be able to do safe calculations via algebraic transformations. Like if P=IV what's I? Plan your learning and put in some on-line effort.

 

[neljan]

I think we'd best advise that you have an electrician have a look at it all.

Hmm I don't think I'm quite at that stage yet. I obviously will do though if I have any doubts at all, but at the moment I'm enjoying learning about it and would get great satisfaction from doing it myself (what happens when you've been with the Mrs as long as I've been!).

I think your initial response was right EFLImpudence, in that he doesn't really need another DB in the loft without a good reason. Perhaps he was intending to wire this new DB directly to the mains, given the size of the feed cable? Anyway, I've learned that the current loft supply is a radial circuit and the newly installed outlets in the loft are on 2 radial circuits.

I'm thinking that I could disconnect the 2 radial circuits from the new DB and wire them to the current powered outlet which is fed from the main CU downstairs like so:



Now I know you're not going to say "yeah that's it, do that!" and I know it's not that simple, but instead of saying "get someone qualified" (with respect) could you at least tell me if I'm on the right track and what else -should I go through with it- I should also consider?

I suppose what I'm saying is that I'm not dissuaded from doing it myself just yet.

Cheers

 

[EFLImpudence]

To be fair, I only said get an electrician to 'have a look'.

It's very difficult from here to understand exactly what is going on.


If the powered cable is protected by a 16A MCB (miniature circuit breaker) then everything could be connected to this cable with a 3A Fused Connection Unit (FCU) for the lights subject to all the requirements of which you are probably unaware.

However, all of this new stuff will probably require RCD (residual current device) protection.
This RCD would likely have to be positioned adjacent (or in if available) the house DB.

It would all require testing to verify it is safe.


A loft conversion, including the electrics, will be subject to the Building Regulations and need a Completion or Compliance Certificate either from the LABC or Registered Electrician respectively.

 

[neljan]

To be fair, I only said get an electrician to 'have a look'.

You did. My apologies.

It's very difficult from here to understand exactly what is going on.

I appreciate that mate and I thank you for trying to advise me given that fact.

However, all of this new stuff will probably require RCD (residual current device) protection.
This RCD would likely have to be positioned adjacent (or in if available) the house DB.

Is it likely that an electrician -after they take a look at the CU- will want to replace the CU with a modern one or would they be able to install an RCD in the existing CU? There is space in the CU for 3 more MCBs. I would show a picture of the CU but I can't get my images from my phone to my PC atm.

It would all require testing to verify it is safe.

That's true.

A loft conversion, including the electrics, will be subject to the Building Regulations and need a Completion or Compliance Certificate either from the LABC or Registered Electrician respectively.

I understand.

I think I will definitely get a professional in. At least now I'll know something about what he'll be talking about thanks to you fella. Cheers.

 

[EFLImpudence]

Is it likely that an electrician -after they take a look at the CU- will want to replace the CU with a modern one or would they be able to install an RCD in the existing CU?

They may well say that.
To be honest it's not the best but that's life.
I'm not sure if their new RCDs would fit but if they do that would be fine.

Either way a separate enclosure with an RCD could be fitted adjacent the board.
The route of cable to the loft will decide whether the RCD is actually required but I would think it is.
Even if it is not required downstairs it will still be needed in the loft.

 

[Alanallsorts]

Please remember that any cable covered by insulation has to be down-rated, most loft conversions have insulation! The lengths and loads on circuits are prescribed in the Regulations. Thus, first read the regulations, please. To certify the safety of work needs a qualified person; insurers will probably want a green or purple-headed certificate, not a plain white one. Curiously, quite what constitutes a qualified person in not strictly laid out. Then, there is that old bogey about write a cert on bog paper and it'll do; there is some truth in this as one cowboy has been charging for "Mickey Mouse" signatures for over a decade! Yet, he is qualified, he just doesn't like paying taxes. You must have a chum who is qualified, why not invite him or her over for Sunday lunch and then ask his or her advice? Do you have any test equipment? You need at least a Digital Multi-meter (DMM) with at least 10Mega Ohms per Volt for accuracy (B&Q used to do a cheap and good one, but it is no use asking them about Ohms per Volt, they most likely will not understand that technicality?); if it's for speed or ease of seeing a moving coil meter is often useful, especially for those who have problems reading a DMM's LCD screen (I recall a course I was on and a Royal Corps of Signals guy burned out an AVO Minor very nicely with a good shower of sparks and smoke, so do learn what to set a meter to before using it!); but my old Avo Mk 8 and similar are only 20,000 Ohms per Volt. Of course, if able to you can use a cathode ray oscilloscope and actually see the traces' representations etc. You do not need one of those to be an electrician, but I do electronics too. Like a pilot, you must learn to trust your instruments (meter/s) too and know exactly how to attach it, etc. Do not go for gimmicks. A chap I know showed off his plug-in-socket circuit tester, it said there was a fault on a circuit I'd done and checked. I checked again, the cheapo gadget was at fault! He wondered why I asked him to bin it! In the motor trade a form of gauge with a line of LEDs is commonly used in circuit testing, they can be used up to AC 400V in some cases (motor vehicles are mostly DC 12V-24V; aircraft voltages vary very widely). However, Mains Voltage is Root Mean Square (RMS) actual peak voltage is the square root of 2 x that amount, so be sure of what your meter is reading! The "destructions", as we called them in the Army, should tell you, on the specifications page. They have to under EU Laws (er, I thought we won those wars?), Ahem!