SWA for chased meter tails

Discussion in 'Electricians' Talk' started by TonyTheBubble, Nov 21, 2014.

  1. TonyTheBubble

    TonyTheBubble New Member

    I'm in the (slow) process of rewiring my house and am replacing and relocating the consumer unit which is currently a 4-way unit and probably pre-dates the asteroid with a 20-way unit which will have individual RCBOs protecting every circuit.

    The consumer unit is in the garage (which I'm in the process of tiling, but that's another story...).

    The old unit is in the corner just below the ceiling (too high...) and the new unit will be on the adjoining wall, diagonally below the meter, just below face height.

    For neatness, I don't want the tails going from the meter externally across to the new meter.

    I will pay an electrician to come and test my work once completed, sign it off and connect the new consumer unit up to the mains.

    I'll also get them to come in before I do too much more work to make sure I'm on the right track to meet the regulations, so I don't have to do things twice.

    I'm trying to do my homework at the moment to try and make sure I get things right so I don't need to pay for too much of their time.

    Now to the question -

    I know that if you bury meter tails, they need protection.

    I'm planning to chase "tails" into the wall running horizontally from the consumer unit, to a switch/fuse unit, and then have the tails coming from the meter straight down and into the switch/fuse.

    The "external" tails will be 25mm tails - probably the existing ones if they're in good enough condition, otherwise standard off-the-shelf 25mm meter tails.

    The "buried tails" are in question...

    I can't find any "swa meter tails" (or 25mm single-core swa) anywhere.

    Could I use two 4mm 3-core swa cables rated, at 42 amps for this?

    My thinking is that if each core is rated at 42 amps, combining all three cores will rate each swa cable at 128 amps.

    I think that combining cables potentially decreases it's current capacity, but hopefully not by 28 amps in this case.

    If I'm correct, then could I use the armour as the earth, or should I run a separate third swa for the earth (as well as earthing the armour)?

    I did buy 25mm 3-core cable, but it's too big (diameter) to bury into brick work without potentially weakening the wall - I won't have to dig as far into the bricks to bury three 4mm 3-core swa cables side by side as one 25mm 3-core cable.

    Also... as far as the "switch/fuse" is concerned, could I use a small (1-2-3-way) consumer unit with a 100 amp MCB for this, or would it need a separate isolator switch? And would it require RCD protection too?

    thanks in advance.
     
  2. unphased

    unphased Screwfix Select

    Hi Tony

    I haven't read through all of your post, I stopped when I got to the "I'll pay an electrician to test and sign off the work." What makes you think that an electrician would want to sign off your work? There are new regulations coming in to force about third party sign offs, and what it amounts to is the electrician being able to see ALL parts of the work at all stages. Attracting a fee for each stage. So for anyone to be in a position to sign off the job they would need to be in a position to inspect it during the installation work. Else they should not sign it off. The mentality of many, including you it would seem, is that electricians are more than happy to do the accepting of responsibility part but the money earning part of doing the installation from start to finish is removed by the person doing it. Sorry mate but the fact you are asking these questions, one that any decent spark can do in his sleep, suggests you aren't competent to be doing it. If you want to do it by all means go ahead but I ain't gonna help. Everyone thinks they can do electrical work but the fact is not everyone can and its about time it was stamped on.

    Good luck.
     
    stu1312 likes this.
  3. Caddy

    Caddy Active Member

    I also Stopped at the same part Unphased did.. You cant get an electrician to come and test once its completed, although it may say in the building regs that you can use a third party electrician for this there is no register as to which electricians you can use and the various registration bodies wont allow there electricians to do this either. Your two options for getting the work done correctly are either paying a fee to the council to come and inspect the work at stages and show them your plans and workings, or paying a registered electrician to do the work..
     
  4. seneca

    seneca Screwfix Select

    Or if you know a registered electrician he might be prepared to let you do some of the work, ie, chasing out the wall and laying the cable in, re-plastering etc, but he would need to be able to see all of the work you do. That could save you some money.
     
  5. TonyTheBubble

    TonyTheBubble New Member

    Hi unphased, thanks for your reply.

    There appears to be a lot of resentment on these forums towards those of us who in these prosperous times don't have thousands of pounds burning a hole in our pocket to get work around the house done by qualified tradespeople.

    Despite what you obviously think, I fully respect electricians and their trade, and from the small amount of work I've done already I appreciate why a full house rewire is as expensive as it is - there's a lot of work and therefore time involved.

    I also appreciate the dangers of incorrect electrical work, and have no desire to ignore/bypass advice/regulations and burn my house down.

    From our side finding a decent sparky (or any tradesperson for that matter) is not always easy. You'd think that living in a first world country like the UK we could simply rely on their reputation and qualifications, but as you're probably aware you can go into a reputable supermarket in the UK and buy beef, and it may not be beef.

    Caddy, Seneca - thanks for your more understanding responses. I appreciate an electrician's reluctance to put his/her name against work he/she is not 100% sure has actually been done correctly, it's their butt on the line, which is why I'd like to get someone in before I do too much work to make sure what I'm doing is correct/safe, and also that they're confident that what I'm doing is safe enough to put their name against.

    I've had a look at my council's building regulations website and looking at their fees it looks like they've turned ensuring safe standards are followed into a money making exercise milking a captive market. Unfortunately this has the effect of putting people off reporting work and makes it more likely that work will not be done to safe standards. Going a little off topic I'm not anti-capitalist but not everything should be for-profit. If you want to encourage people to do something, you have to make it easy for them. And where safety is concerned, that encouragement should be a carrot, not a stick. And that's not having a dig at electricians, it's having a dig at politicians.

    My options are limited - I won't be plugging the new consumer unit into the mains until I'm satisfied the rewire is safe - I don't want bad things happening while I'm asleep in bed. And I won't be doing too much more work unless I know that I can plug it into the mains at the end of it.

    cheers
     
    Ray Retired likes this.
  6. Coloumb

    Coloumb Screwfix Select

    Tbh mate a lot of us have put a lot of effort into learning what we know which can't really be imparted to someone who doesn't really have that much of a clue. Sorry to sound like a c**t, but you don't. You need to get spark in to do what you propose who can do thi properly for you.
     
  7. spinlondon

    spinlondon Screwfix Select

    The reason why you cannot find single core SWA, is because the Regulations do not permit it's use.
    What you suggest with the 3 core SWA, would also not be permitted.
    You can use AWA (Aluminium Wired Armour) cables in the manner you suggest, but not steel.
     
    Pete Jones and FatHands like this.
  8. JP.

    JP. Screwfix Select

    The whole thing sounds like a potential lash up to me tbqh..buried meter tails, pfffftttttttttt
     
  9. unphased

    unphased Screwfix Select

    @tonythe bubble

    What you don't appreciate Tony is the amount of hassle us professionals have to deal with day-in-day-out due to people having a go. There is a right way and a wrong way to go about this. It is the LAW that requires you to NOTIFY building control BEFORE you begin ANY work, especially a rewire which is a major job, and tell them that you intend to do what you are doing. The onus is on YOU to do this, not the electrician. I am fed up of people claiming ignorance of Part P. Part P has been in force now since 1 January 2005, thats near as dammit ten bloody years and people are still flouting the Law. You cannot do it all yourself without having it inspected at each stage for which there is a FEE. How much is dependent upon the Council in your area. It is not allowed to do it all and then just expect someone to come along and sign it off. Why tf should they! Like I said there is a right way and a wrong way and you are clearly not complying with the Law. You are already too far down the line if you have already done a substantial amount of the work so its your problem mate.

    Thank you.
     
  10. sparky Si-Fi

    sparky Si-Fi Screwfix Select

    OP

    Agree with all my fellow sparks, we are also not a cheaper form of Building control, as Roy as said you are too far down the food chain now and getting someone to sign your responsibility away is wrong and if any issues come up, he is the poor bloke in court


    I will pay an electrician to come and test my work once completed, sign it off and connect the new consumer unit up to the mains.

    Wish you all the best on that aspect. . . .

    Not to mention:

    Now to the question -

    I know that if you bury meter tails, they need protection.

    You cannot bury tails, end of

    You cannot simply make your own manual for your own work, we all have to work to BS7671 with all the updates and test kit to comply.

    A little bit of knowledge is a dangerous thing.
     
    Last edited: Nov 24, 2014

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