Bus bars and MCBs

[RossR]

Please don't take any of my comments as a personal attack. I'm not saying you're stupid. I'm saying I don't think you have the necessary knowledge. For example PSCC has nothing to do with selecting a B, C or D type MCBs (Although they are related to inductive loads).

You have some knowledge, but I'm sure you know the saying about "a little knowledge".

I'd be very interested in an answer to this by the way:

What diameter did you measure the conductor to be?

 

[WillMu]

>I'm saying I don't think you have the necessary knowledge.

And I'm not saying that PartP is a stupid idea or that it has no point. In fact, I came here to make sure that I make everything comply so that I am not wasting the time of the person who I am asking to review my work. If that means that I have to ask him to bring and fit a new CU, then that's really something I need to know in advance!

>For example PSCC has nothing to do with...
I read you comment to mean - "you know how much current you might accidentally send down that wire?" - I know that a fuse doesn't burn out as soon as it gets a little over current (although, 100A is still going to hurt anything that blocks its way).

I was trying to demonstrate that I was aware of the dangers that lurk in that plastic box, and I don't need an acronym to tell me that, it just gets in the way of communication.


>You have some knowledge, but I'm sure you know the saying about "a little knowledge".
You can only learn so much by reading the standards - the rest you learn by asking or screwing up!
Lets just say, I'd rather ask the questions and be assumed a fool than be proved one by the insurance company and or the fire brigade.

>What diameter did you measure the conductor to be?
The wire is measured at 2mm diameter, which I have just realized does not match "Cross Sectional Area" because it's round. I really hope I measured the wrong off-cut now

I really need to re-check this don't I? (I was hoping to avoid touching most of the red n black circuit except for using junction boxes where I had removed sockets from the kitchen).

 

[RF Lighting]

I would hazard a guess that inside the CU there is an option to pull -for a moment- what, 800+Amps thru the 100Amp fuse.

Put another 0 on the end and you'll be a lot closer.

 

[Spark123]

Spark123, Yes, those, and I would return them and get the right ones if there was somewhere locally to get them.

Why not just buy the one I linked to for £6 off ebay? Put the other one on the shelf so you can look at it and think "why did I think I could fit fiesta brakes to a golf."

Spark123, that legrand picture looks like a set of dodgy dentures

 

[automationman]

WillMu, without a good understanding of the technical terms (the technical parameters) which are well understood and must be well understood by all electrical engineers/competent people, then you are working in an unsafe manner if you work on your consumer unit/modify your consumer unit. That is why you have raised concerns with many of the people who have replied to your posts. It is out of concern.

You risk injury to yourself and others and your property. I am guessing you feel confident in what you are doing but thats like feeling confident about running through a dark room without bumping into the furniture when you haven't seen the room before (you won't know what you are about to hit, or what is about to hit you) This is really simple, if you do not know what Ze (External Earth Fault Loop Impedance, the impedance of a LINE-EARTH fault from your CU through the supply cables, through the supply xformer back through the earth circuit, back to your MET @ 50Hz) is then you should not be working on a consumer unit (or any high current equipment) for reasons of safety.

It sounds like you don't have the test equipment to check what you have done is safe anyway? Do the right thing and get a professional in to look at what sounds like a bit of a disaster zone.

 

[automationman]

Have a look at some of these videos and please don't think that you won't be able to reproduce some of these events in your consumer unit! I assure you that you can....if you want

http://www.brainfiller.com/newsletterArchive.php#arcFlash

 

[ban-all-sheds]

And I'm not saying that PartP is a stupid idea or that it has no point. In fact, I came here to make sure that I make everything comply so that I am not wasting the time of the person who I am asking to review my work.

In terms of complying with the notification requirements in the Building Regulations, asking someone to review what you've already done is not how it works.

The wire is measured at 2mm diameter, which I have just realized does not match "Cross Sectional Area" because it's round. I really hope I measured the wrong off-cut now

I'm fitting a new circuit for a kitchen as I found that all sockets in the whole house were on a ring of 32Amp on cable that measures just less than 2mm

Just less than 2mm?

How does 1.78mm sound? i.e. the diameter of 2.5mm² cable. Which is just fine for a ring final on a 32A MCB, and didn't need to be replaced.

I really need to re-check this don't I? (I was hoping to avoid touching most of the red n black circuit except for using junction boxes where I had removed sockets from the kitchen).

Why were you removing sockets? You'd have to replace them with blanking plates which would have to remain accessible. Removing all evidence of accessories but leaving the cables there would be illegal, and having inaccessible junction boxes is a contravention of the Wiring Regulations. Might as well leave the sockets and use them.

Lets just say, I'd rather ask the questions and be assumed a fool than be proved one by the insurance company and or the fire brigade.

The thing is, rewiring, installing new circuits, a new CU etc is not a trivial job, and I can assure you that it involves knowing far more than you think it does.

Asking questions here can be a useful part of a learning process, but they are not a substitute for proper structured studying. The key term there is "learning process" - you cannot learn all the things you need to know just by asking questions here. It isn't structured enough - it won't provide you with a way to progress where each step builds on what you learned before.

You can't carry out a job of this magnitude by asking whatever random questions happen to occur to you. You've already shown that you have some dodgy misconceptions - what if you get something wrong because you have no idea your knowledge is wrong? What if you miss something because you simply have no idea it even exists, and just don't realise you don't know it?

• //www.diynot.com/wiki/electrics
  
  
• //www.diynot.com/wiki/electrics:books
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/electricity.html
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/domesticinstallations.html
  
  
• http://www.tlc-direct.co.uk/Book/1.1.htm[/list]I suggest you get stuck into the last link right away - it won't give you design ideas, and unfortunately it doesn't refer to the current edition of the Wiring Regulations, but it's free, and will still give you a good grounding which you can augment with more up to date publications.

 

[Adam_151]

I would hazard a guess that inside the CU there is an option to pull -for a moment- what, 800+Amps thru the 100Amp fuse.

Put another 0 on the end and you'll be a lot closer.

Not unless the local transformer is right outside the back door

 

[flameport]

Legal and competence issues aside, just why would anyone go to such lengths and incur significant risk to fit the wrong MCB in a consumer unit?

Legrand is a major manufacturer of electrical equipment, their consumer units are widely available, and the correct MCB would typically be £3 or £4.

 

[automationman]

For the same reason that you would rewire a perfectly serviceable, correctly wired and properly protected 2.5mm ring final circuit with a 4mm untested, uninspected, unconvential risk. Sounds like the OP shot first then asked questions later, several times