Legal cable concealment and FCU question

Discussion in 'Electrics UK' started by jbuild, 20 Jan 2010.

  1. jbuild

    jbuild

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    trying to make sure I am following 17th regs on cable concealment. In this case to do with extending circuit and/or using same channel for AV cables and power.

    I have drawn two plans for starters as I know you like pictures

    In plan 1, the power goes all the way to a socket behind TV. AV cables go in and out of a channel on other side of stud.

    In plan 2, the flex from the TV goes through same behind wall channel as the AV cables. Does plan 2 fail because of mixing AV and power cables and because of the 50mm cable depth required for electrical cable concealment?? Any solution to this?

    background....
    The wall is an inner layer of 19mm plasterboard directly overlaid with an outer 12mm plasterboard. All on wooden studs. It is a wood framed building. There is what looks like fibreglass loft insulation in cavity behind the inner plasterboard.

    Both plans extend the power circuit to give a socket or sockets nearer the TV

    The existing 2gang socket would be converted to a 1G that leads to a 13A switched FCU that then leads to all power sockets for TV , dvd player etc.

    There is a gap behind the approx 80mm depth studs to fish power cable through so I should be ok with the required 50mm depth regs when extending the circuit and concealing wire? At least 50mm on the other side of the new power cable run too.

    I aim to use drywall pattress boxes with holes cut in them to allow a neat entry of AV cables in and out of the wall.

    AV cables would enter and exit wall via brush plates like:

    http://www.wickes.co.uk/Single-Gang-Brush-Faceplate/invt/204733?source=123_4

    Or via a blank plate with holes drilled in and cut in two. Av cables go in/come out of pattress box and then put two pieces of blank plate back on with cable ends hanging out of drilled holes.

    Ideally I would like to get a conduit for AV cables into the cavity behind the plasterboard but all I can think of is 65mm square guttering downpipe IF I can get it inside the wall without cutting huge pieces out of the wall. Fat chance.

    On far left is an old brown cable aerial socket. Tempted to leave it be. I cant find where it leads and existing aerial (not used now) comes in through exterior wall !??!

    Any help and advice appreciated. The AV forums don’t seem too hot on regs. Don’t mention D-line exterior conduit.


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  3. Steve

    Steve

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    I'd go for 2. Many newer TVs stupidly have their connections pointing straight back, so all your plugs end up bend at 90 degrees against the wall. And you probably wont have space for a plug and socket up there,

    UNLESS you go for opotion 1, but use an FCU behind the TV instead. This would work. Chop the plug off the IEC lead, it only needs to be a foot long or so, and wire it into the FCU (make sure you use the fuse that was in the plug you chopped off)

    Also, if you butcher the IEC lead (provided it has one of course), use a different one to the one supplied - then the manufacturer cant claim you damaged the equipment by messing with their lead (make sure you keep their lead safe you you can claim you used it all along). ;) I have a few IEC leads knocking about. You'll find one on ebay if you dont. ;)
     
  4. FourFootMedia

    FourFootMedia

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    I'd go for option one, much tidier - no cable going from a plug in to the wall and you're keeping your power and signal cables seperate.
    But as stated, probably use a FCU with flex outlet rather than a single socket behind the TV - all depends how much room your wall mount provides (if you've room for a socket and plug it makes changing/maintaining the TV easier I guess).
     
  5. jbuild

    jbuild

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    I found this posted some time ago by Ban-all-Sheds on this forum

    "Regulations prohibit Band I (ELV, telecoms, signalling, audio, video etc) cables from sharing enclosures with Band II (all other voltages used in electrical installations) unless every cable is insulated for the highest voltage present. So unless the insulation on your AV cables is rated at 230/400V that's another regulation you've broken and more potential danger you have created."

    So this means Plan 2 is illegal.
     
  6. jbuild

    jbuild

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    The FCU is positioned where it is to allow

    1) conversion of the exisiting 2gang socket to a point I can spur off to a total of 13A without breaking regs on spurring off a spur.

    2) to allow all AV stuff including TV to be switched off without fumbling behind the TV, DVD etc while still allowing the single socket to be used e.g. for a lamp
     
  7. electronicsuk

    electronicsuk

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    Ditto. This sounds like the most sensible option.
     
  8. jbuild

    jbuild

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    Probably go for a switched FCU with flex outlet for the IEC as suggested as there isnt much space for a standard plug plus socket. Can get them without the switch but why not.

    will put the 3A fuse from the TV plug in it

    Thanks for the idea.

    Going then with plan 1, I still think I have to use the 13A FCU after the first 1G socket (bottom left) so that I can extend the circuit without falling foul of spurring off a spur.

    Not sure if clear from diagrams but only socket currently there is the bottom left hand 2gang in purple.
     
  9. Steve

    Steve

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    I'm not sure how good an idea it is to hang the wall mount on one stud either. I'd span 2, or cut out a chunk of plasterboard, replace with plywood across the 2 other adjacent studs. Then use this to support the wall mount.
     
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  11. ban-all-sheds

    ban-all-sheds

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  12. jbuild

    jbuild

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    Is everyone happy that the wiring diagram in plan 1 is ok and meets regs? Plan 1 is now a 2gang socket converted to a single that spurs to an adjacent 13A switched FCU that leads to a 2gang that then leads to a 3A FCU flex outlet behind the tv, the last bit being the only change on grateful advice here.

    on the other notes...

    ha, i knew wireless was coming. It will take a while to come to me though

    The stud is a hefty support beam of a wood framed house rather than a stud just for hanging plasterboards onto. There is also a cross piece so shld be ok.
     
  13. A FCU behind the TV is the best option. You can get better quality IEC connectors from Farnell, RS, CPC etc and you can get right angled ones. So they take up less space. I would not bother cutting up the lead just buy a connector and use some 1.5mm 3 core flex. This is how I do it when I get chances to install something like this. The connectors are easy to fit.

    Example:

    http://uk.farnell.com/bulgin/px0587-se/socket-iec-right-angle-free/dp/1172510

    Adam
     
  14. jbuild

    jbuild

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    Does the below affect the decision to use an FCU flex outlet??

    Just looked at the current IEC flex to the TV.

    From the end that plugs into the TV it looks like a polarised C7 or C8 IEC . There is a moulded plug on the other end.

    see variants at:

    http://en.wikipedia.org/wiki/IEC_connector

    The polarised C7 is asymmetrical, with one end rounded similarly to the unpolarised version, and the other squared off. Which is the neutral/live? Does it matter?

    Maplin do this lead if I dont want to cut the plug. Again, do i need polarisation?


    http://www.maplin.co.uk/Module.aspx?ModuleNo=1167
     
  15. ban-all-sheds

    ban-all-sheds

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    And in other places you can get them made from oxygen-free kryptonite which has been stored in liquid nitrogen, then bathed in the tears of Essex virgins and finally plated in 99.99% pure spucatumtaurium.
     
  16. jbuild

    jbuild

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    I just want to get it done, all without breaking any regs. Help
     
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