Replacing consumer unit - need junction box (SCOTLAND)

[sltech8]

I have just read with interest all the posts on this thread and I would just like to know one thing......whats the address of IEP, because I certainly wouldn't want to make the mistake of being the next owner.

Advice to IEP. You are leaving yourself open to major disaster mate. If you value the lives of your family and anybody else that lives within burning distance of your property, get a good sparky to do the job.

If there is one thing in life that is certain, it is that a little knowledge can be a very dangerous thing.

Just make sure you check that the sparky is a good tradesman, word of mouth referrals are always good. Check that the electrician have done a proper apprenticeship not just a twelve week (i know everything) course.

It does sound like you are either trying very hard to prove a point or you are trying to save a few quid......either way its not worth it!

 

[Taylortwocities]

Okay, you've lost me. It's all done in twinand earth of the appropriate gauge but, due to the age of the installation, the insulation is red and black.

What would be the problem?

iep

It was done in 1978 in good old twin and earth of the appropriate gauge at the time.

At that point the twin and earth used for ring final circuits had 2.5mm² line and neutral conductors and the cpc (earth) was 1.0mm². This was fine for earth faults using rewireable fuses (thats your existing fuseboard).


Now, you are going to replace your rewireable fuses with contact breakers that have a totally different characteristic. They comply with BS EN 60898 instead of the old BS3036.
Are you aware of what that means to your ring final circuits in the "good old" red and black cables???
Do you know what to look out for and what action to take?

(Hint: the 2.5mm² twin and earth cable that you buy today has a 1.5mm² cpc/earth rather than 1.0mm². I wonder why......)

 

[iep]

Thanks for the posts guys. Especially tailortwocities', useful info.

sltech8, thanks for your note of caution. Rest assured, I am not about to do anything half arsed. I am not trying to prove a point and I am not overly concerned about saving money (at the exopense of risk). I simply prefer to do things myself where I can.

I know I am about to open myself up for a load of abuse here and I'll start by saying that I realise that I am not qualified in any way to re-wire a house. However, I have a degree in electrical and electronic engineering and am a chartered engineer in the field of elctrical engineering. Now, I'll say it again. I absolutely agree that this does not mean I know how to rewire a house (I wouldn't trust half my colleagues to wire a plug). I don't know the relevant standards and I don't have the years of experience that would allow me to avoid the many pitfalls.

However, I am capable of understanding the issues and that is why I started this post. I want to know how to replace the C.U. and I want to understand the complexities of the task. Once I understanbd what needs to be done I will either do it myself and get it profesionally checked (if I think the risk is low). Or, I will hire a local sparky to do the job for me while having the advantage of understanding what he is doing and why. Either way, I've found all the info form this post to be very useful.

I also think it's useful info for other people who are in my position and that is what forums are for.

Cheers,

iep

 

[iep]

Taylortwocities, I've been thinking about the 1mm to 1.5mm change that you mention and can only come up with one obvious reason for this:

1mm cable can cary up to 16A when clipped to a flat surface (and not insulated). However, it can only carry 13A when installed within a conduit within a wall. 13A (best case, 26A on a ring main) is a bit low since the fuse on a ring main won't blow until the current hits 30A or 15A on a radial Spur. This gets even worse when you move to a 32A MCB for ring and 16A for radial.

1.5mm can carry up to 20A when clipped and 16.5 when within an insulated wall so it is a safer proposition.

Am I close?

iep

 

[echoes]

5. Bathroom shaver socket 15A

That's one powerful shaver.

 

[iep]

Where'd you get that picture of me?

 

[echoes]

...not that I make a habit of googling 'chainsaw' and 'beard'. Looks a bit straggly though... prefer a nice Remington myself!