TT & Part L

Discussion in 'Electricians' Talk' started by wally, Jan 14, 2011.

  1. wally

    wally Screwfix Select

    Evening all, just after clarification really on a couple of things.   1.  Just fitted 8 GU 10 in a kitchen & the lamps are the energy efficient ones ie 35w equivalent to 50w.  Would this count in regard to Part L of the building regs.   Talking about an existing house not new build.
    2.   On a TT install is the double pole isolating switch on the consumer unit still counted as complying with double pole isolation.   There was another query but I have  forgotten what it was, must be my age.
     
  2. pefc

    pefc New Member

    youve answered both your questions yourself, not a new build, so dont concern yourself with the fittings, and yes a double pole isolator isolate both poles complying with double pole isolation
     
  3. seneca

    seneca Screwfix Select

    Agreed.
     
  4. wally

    wally Screwfix Select

    Hi pefc, I have heard that Part L now has been altered to apply to rewires, perhaps it doesn't.   But my question was really about the lamp, does it now become a part L lamp
     
  5. pefc

    pefc New Member

    Morning wally, im almost certain that part l does not apply to rewires, but then again things change and i can see it happening one day, maybe speak to your local council building control to get a definite answer.  As regards to the lamp being compliant to this, then im not totally sure, i was of the opinion that the lamps had to be CFL or similar, to me 35W compared to 50W isn't a great reduction in wattage, if you compare them to the 3W LED or 8W CFL and there was something about the fittings, that you have to make sure the lamps in them cant be replaced with the old incadescent lamps, but again, im not massivly up on it mate.
    I would say that all main incomers have to be double pole, regardless of the supply type.
     
  6. JC2779

    JC2779 Member

    Part L applies to both new and replacement (rewired) circuits and there is a minimum recomended requirement for 3 in 4 fittings to be low energy (75%) they can either be dedicated LE fittings or supplied with LE lamps either CFL or LED lamps are classed as low energy GLS filimant lamps or tungsten halogen lamps do not meet the requirements for low energy lamps regardless of wattage.

    As for double pole isolation. Every circuit must be capable of being isolated from each of the  live supply conductors. A neutral conductor falls within the definition of a live  conductor. With permitted exceptions for TN-S and TN-C-S systems. Isolation of the  neutral conductor of a circuit in TN-S or TN-C-S systems is not generally  required where that conductor can be regarded as being reliably connected to  Earth through a suitable low impedance. Since a Neutral conductor is classed as a live conductor and it is not reliably connected to earth then isolation in a TT installation is required to be double pole.

    Yes the double pole main switch does comply with double pole isolation, however if you were to isolate part of a TT installation by locking off the MCB / Protective device only that would not comply as the neutral conductor would still be connected you would need to disconnect the neutral conductor as well. The regulation is more suited to commerial / industrial situations, although not many installations are supplied by TT. However if you were to come across such an installation and any part of the installation required isolating lets say a machine then you would need to make sure that the neutral is isolated via the isolation switch as well as the phase conductor.
     
  7. wally

    wally Screwfix Select

    Thanks pefc for your comments & for you JC with clarity of the situation.   They were my thoughts JC on both issues.   When I put the recessed lights up I seem to think the boxes they came in said part L compliant but guess its just a selling point but not strictly correct, I will check it out when I next get one.
     
  8. Removed 4

    Removed 4 New Member

    Shame on you Wally for asking such a ridiculous question at your age and with your experience !  The B.Regs 'L'  do not apply at all in this case, as outlined in your O/P.

    Moreover, if you wish to follow Part L (unnecessarily in this case) to the letter: The recent changes have brought about a change to the quota of so-called energy saving lights.  Instead of the original requirement for fittings to be 'energy saving', they now word it in terms of the actual number of lamps.  This means that any fitting may be used and that the lamp type only needs to be compliant for the duration of the BC inspection - thereafter, the householder is quite at liberty to revert to tungsten or halogen lamps.

    Lucia x
     
  9. wally

    wally Screwfix Select

    Hi Lucia, thanks for that.    It does not matter how long iv'e been in the game Lucy it's a job to keep track of the part L & the like when they keep altering it.    I self certify my own work so BC are not involved not as a visit anyway.    I don't see so much importance of special fittings now as many of the standard bulbs are becoming low energy types anyway.   The only good it has done is for new developments of new type lamps.   I think using a dimmer is as good an energy saving device as any.
     
  10. seneca

    seneca Screwfix Select

    But the energy that isn't being used in the lamp is being dissipated as heat in the dimmer Wally, admitedly not all of it as it uses a chopper circuit but  there's probably not much of a saving there?
     
  11. Removed 4

    Removed 4 New Member

    Odd, isn't it, that this minor nation of slightly less than 1% of the population of the planet, should be so concerned with saving energy, when the other 99% couldn't give a damn?


    Lucia.
     
  12. wally

    wally Screwfix Select

    Very true Lucy, its another tax in diguise
     
  13. pefc

    pefc New Member

    see now im really confused, some are saying that part l applies to rewires and some ar saying it clearly doesnt.
     
  14. wally

    wally Screwfix Select

    Your not the only one pefc
     
  15. J.P.

    J.P. New Member

  16. wally

    wally Screwfix Select

    Ive looked at that before JP, which bit should I be looking at as it makes no sense to me at all.    I cannot see any reference to use of low energy lighting in an existing dwelling as Lucy indicated but others have different views.   It would be useful for someone to point out the section it refers to see it in black & white.
     
  17. J.P.

    J.P. New Member

    Likewise Wal..I suppose if my extension goes ahead then a lot of reading is required with respect to insulation and this and that to satisfy BC inspection. Tbqh I don't expect any problems with the electrical side of things as from what I gather you just whip in a few CFL's and then whip em out after a pass..saying that I have some CFL's in my house at present and am pretty impressed by them..some were free and some cost I think it was a squid for four. The Megaman in my exterior lantern I am well pleased with. I think all this Part L is down to common sense, and of course complying with whatever reg you have to. Spose you have to sift through it a bit.


    Anyway have a good afternoon Wal.
     
  18. wally

    wally Screwfix Select

    Ive got some in 2 table lamps which are fine JP & for outside lights, even a 24w in my 500w flood on a pir & a lantern out the front on a photocell, these being ideal but most of the indoor lights I would rather have filament on dimmers (11 dimmers in the house) & I can choose what level I want the output.   I would not want a main living room light at the same brightness at 7pm as I would at 11pm.   So now we have a job to get bulbs at 30p but we can get the halogen version at £3, more tax & vat to be made, oh well it must help the countries funds JP.    Are we the only country doing this, makes you wonder.
     
  19. JC2779

    JC2779 Member

    The infomation you are looking for is no longer specifically specified in those documents JP listed. Instead those documents refer to the newley named Domestic Building Services Guide 2010 Specifically Section 12 Lighting. Of course its up to the person who is installing the lighting to decide if there going to follow the guidance in order to meet the requirements.

    On a side note the reason its only guidance and not requiremnet is that the efficency of a house is looked at as a whole but in order to meet the requirement the guidance should be followed.
     
  20. wally

    wally Screwfix Select

    Thats cleared that up then JC, as all my work is existing domestic I shall use it as guidance only so I will be doing what I always have, make my own judgement.  When it comes to outside lighting I usually advise low energy or photocell or PIR so I think I am doing my bit.  Many thanks for coming back, I think thats cleared it up very well.
     

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