16mm meter tails in what size conduit?

Discussion in 'Electricians' Talk' started by Strima, Feb 25, 2012.

  1. Strima

    Strima New Member

    Hi all, first post and all that lovely stuff.

    Doing some work for my brother-in-law in his one bedroom flat he is going to rent out.  He wants a new CU and condition report completing which is easy done.

    I've had a quick look and his meter tails are a little old, 50's built property using 10mm rubber coated tails which need upgrading.  The old tails run through what looks like 3/4 inch copper pipe to a communal utilities room and I doubt there is any way in hell I'm going to get two 16mm tails and earth down there.

    The property is ex-council and the meter tails have been upgraded to the suppliers isolater switch but it appears no other work has been done since the installation was originally done.

    It is a run of roughly 10m, roughly 5m of which is outside with plenty of bends.  The old copper pipe has been concreted in and I'm not up for digging up his entrance.

    So my question is:  What size steel conduit will 2x 16mm tails and 16mm earth fit down?  20 or 25mm?

    I'm tempted to go down the SWA route just for ease.

    I have never had the urge to work with steel conduit in the past so I thought I'd best seek advice from somewhere and you'e the lucky buggers I've chosen...

    Thanks all. 
  2. J.P.

    J.P. New Member

    Welcome to the forum Strima..:)

    25mm steel conduit with 2 x 16mm and 1 x 10mm and bends = no chance - SWA? .. think of the bend radius..it aint exactly gonna bend 90 deg's, maybe 45 obtuse. The forum electricians will advise accordingly on the correct deployment strategy Strim.
  3. Lokkars Daisy

    Lokkars Daisy New Member

    You will get them down 25mm , with bends, at a push, with wire lubricant , I presume you will have to use sheathed tails. You could probably use a 10mm earth if the going gets tough perhaps the conduit it;self will be sufficient as an earth if you are stuck.   I would prefer to use SWA but it depends on the circumstances

    maybe it is no chance with bends JP Idunno

    The forum electricians will advise accordingly on the correct deployment strategy Strim.   :) Remind me of a receptionist at the doctors
  4. J.P.

    J.P. New Member

    I've never tried it tbqh LD - just visualizing it. Your idea of 2 x 16mm and using the steel conduit as a earth seems viable..but even with just two 16mm it seems a no go if a 90 is used on the run I would think.
  5. J.P.

    J.P. New Member

    All with ref to sheathed (meter tailing)
  6. Lokkars Daisy

    Lokkars Daisy New Member

    What dy know JP , just popped the radio on , probably 4   and playing is Gullivers Travels drama , the last travel where he meets horses and talks to them, these have a Sweedish accent, in the book they have more of a horsey voice          I wonder if they will comply with the original as it;s just as crazy as his earlier travels      He and the others ,horrible human types the horses call YAHOOs

    later on in my listening,,, It has been severely edited, cut short by 80% perhaps ,, parts have been juggled about , some earlier, some later than in the original , some extra stuff the invention of the director,
    all in all listening to it, this radio drama is great entertainment, like much other radio stuff.
    is luverly
    Radio is
  7. Strima

    Strima New Member

    Cheers for the replies so far.  This is why I'm taking my time to research it a bit.  If I could get away with a straight run then there would be too much to worry about but trying to get the cable through the twisty bits did make me rub my chin and tsk a few times...

    There is a 10mm earth running from the CU but is disappears into the ether and I didn't have the tools to test when I last went as it was to look at sorting out his kitchen.  Altough there are three lighting circuits on a one bedroom flat...

    If I read the regs correctly any cables running in the same conduit must have the same CCC, I'm guessing this is the same for meter tails hence the 16mm earth.  Shame I can't use the conduit as an earth, that would save a few headaches.

    The communal utility room is no more than an old coalshed and is a complete mess, it supplies four flats but there are enough boxes and cables in there for at least double that.  The suppliers have even left the old meters in from when they upgraded to the digital ones as well as a couple of key meters. Not to mention old pushbikes and kids toys.

    His flat is empty as of mid March so I can then get in and really get to work, hopefully this 10mm earth will lead back to the MET then it should be quite easy.

    And I will be using sheathed tails.  The suppliers fuse is rated at 60A so using 16mm should be sufficient for any future upgrades.

    Thanks and keep 'em coming.
  8. J.P.

    J.P. New Member

    I'm not au-fait with the regulation which sais that all cables running together in the same conduit must be of the same CSA Strim - please could you elucidate a tad on said, perhaps with a reg number.
  9. J.P.

    J.P. New Member

    Gullivers Travels LD - not au-fait with it, but have heard of it - I seem to remember the giant (normal size to us) being tied down onto the ground - must be good to get into those stories. I listen to some plays on Radio 3 sometimes, better then the TV a lot of the times.
  10. J.P.

    J.P. New Member

    A one, a two, a one two three four

    3 wires down a pipe------------3 wires down a pipe, ----------------eeeee iiiiiiiii adio, three wires down a pipe

  11. Lokkars Daisy

    Lokkars Daisy New Member

  12. Lokkars Daisy

    Lokkars Daisy New Member

    Maybe to do with induced currents JP , however I don't think that applies to the CPC   , and why can't he/she use the conduit as an earth conductor
  13. J.P.

    J.P. New Member

    Dunno LD about the conduit as an earth conductor in the chaps case as he cant see much of it from what I gather. Far be it for me to say (never come across Strima's situation before) but if Strima did decide to use the conduit as an earth then perhaps he would have to hard test it first - cannot see a standard continuity test proving much tbqh?
  14. Lokkars Daisy

    Lokkars Daisy New Member

    Yes he could hard test it JP, that uses or at least did do, more current than your Megger puts out.. There are plenty of tables though that will gice the csa etc of steel conduit

    What about the Brennan then JP , I know yer a photo man but yer also a sound man ,,Brennan Just Talk
  15. Lokkars Daisy

    Lokkars Daisy New Member

    Tra la la :)
    Can't help singing your new tune JP ,,, oh well it makes a change from your lightswitch song ,which I've been humming since you composed it
  16. Strima

    Strima New Member

    If it was a sub circuit then I would, at a stretch, use the conduit as a CPC but as this is from the supply to the CU then I'm not even considering it.

    As for the same CCC in conduit, I know it applies to band 1 & 2 but not 100% where it applies to this situation as it is the main supply for the CU, if this circuit fails to protect then I will be in a world of pain. Chapter 52 covers it but nothing specific to this installation.

    There's no legal requirement for him to have RCD protection when renting the flat out but he wants it for his own piece of mine and the obvious insurance reasons which I can't blame him for.

    I won't even mention my father-in-laws house which has been extended so much the original CU is now a sub-main protected by a 15A RCBO providing power to 80% of the house and everything trips, that's my next job to sort out...  But that's a different thread.

    Hopefully I can track this 10mm earth back to the MET and only have to worry about mechanical protection for the 16mm tails.  Shame it's not in China, I could get away with a couple of coathangers twisted together...
  17. Lokkars Daisy

    Lokkars Daisy New Member

    Strima, your arguments are flawed , and now I can't be A rsid to explain why
    seneca or JP or others will ellucidate
    PS do you like films with Gladiators in , fighting in an arena n stuff ?

    The Sun looses 4,000,000 tons every second
  18. seneca

    seneca Screwfix Select

    I think i'd go the 16mm swa route if at all possible Strima.  You mentioned an isolator, is this a switch-fuse as most dno';s require this if the tails are more than 3-4 m  long.
  19. J.P.

    J.P. New Member

    Brennan LD - hmmmmm I don't know what system your using at the moment but it seems to me that you might just as well rip all your CD's onto a laptop and use the laptop through your sound system..probably via the SPDF out on the laptop. However the JB7 does look like a fair bit of kit, but it does have limitations from what I have just read - ie the FAT 16 or Fat 32 Hard Drive - can be somewhat limiting with ref to the 16 as I think this only allows a max a partition of 2GB, and the FAT 32 is limited to 32 GB partition size - so multiple partitions would have to be made ,  and I see no ref to NTFS which would be better. I see it has an internal database which more then likely covers the ripping of most CD's without having to manually input track names etc, however using a PC or laptop would allow a web link to name stuff - one good one is Real Player. Difficult to quantify LD, and give an outright opinion on the JB7. Also as a point of note the ripping quality is not to good with the default - which means upping the compression with a view towards using lossless on some Classical music etc..it could fill the HD up rather quick LD.
  20. Strima

    Strima New Member

    The isolator is a MEM double pole, looks like it's original as the other three on the board are the same.  There are signs of upgrading from the incomer to the isolator on all four installations including key meters that have been there a few years but all meter tails look like the original stuff put in, the 10mm rubber sheathed stuff is looking a little tired on all.

    Apparently my arguements are flawed, can't actually see any arguements, just me seeking advice of people with more experience than myself and asking relevant questions.

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