Results 1 to 4 of 4

Thread: downlighters

  1. #1
    Suspended
    Join Date
    Oct 2007
    Posts
    2,346
    Thanks
    0
    Thanked 254 Times in 209 Posts

    downlighters

    12 volt and 230 volt downlighters.

    mounting the transformer?

    exposed wiring?

    fuses for the output side?

    distance from the transfomer to the lamp?

    using a 300 va transformer and sizing the conductors?

  2. #2
    Diamond Member AndyD's Avatar
    Join Date
    Jan 2010
    Location
    Cape Town
    Posts
    4,403
    Thanks
    513
    Thanked 854 Times in 687 Posts
    Hi Murdock,
    Have you a particular installation you are enquiring about or are you just asking about the general rules that apply?


    Quote Originally Posted by murdock View Post
    12 volt and 230 volt downlighters.
    You can't really lump the 12v and 230v lighting systems into one question because they fall under a completely different set of rules.

    Quote Originally Posted by murdock View Post
    mounting the transformer?
    There's various rules covering the mounting and positioning of transformers.
    Code:
    7.9.3.1.1 Components shall be mounted in an enclosure, ventilated
    where necessary
    Code:
    7.9.4.4 Transformers, protective devices or similar equipment mounted
    above false ceilings that are moveable, or easily accessible, or in a
    similar place, shall be mounted on a fixed part of the building such as a
    beam, and information shall be given about its presence and location
    Code:
    7.9.3.3.1.4 The ELV power source shall not be installed above the lamp
    or within 200 mm from the lamp to any side unless a heat barrier is
    installed between the lamp and the power source.

    Quote Originally Posted by murdock View Post
    exposed wiring?
    On the primary side (LV) or secondary side (ELV) ??
    Code:
    7.9.4.1 Primary terminals of the supply source shall be in an enclosure.
    Code:
    7.9.2.4.1 Bare conductors may only be used in an extra low voltage
    lighting installation system if
    a) the nominal voltage does not exceed 25 V a.c. or 60 V d.c.,
    b) the wiring system is made up of compatible components and complies
    as a complete unit with SANS 60598-2-23/IEC 60598-2-23
    (SABS IEC 60598-2-23), and
    c) the conductors are at least 1 m from the thatch under a thatched roof.
    
    7.9.2.4.2 If both circuit conductors are uninsulated and supplied from a
    convertor that complies with SANS 61347-2-2/ IEC 61347-2-2
    (SABS IEC 61347-2-2)), the power of the convertor shall not exceed
    200 VA. Amdt 1; amdt 3

    Quote Originally Posted by murdock View Post
    fuses for the output side?
    It depends...
    Code:
    7.9.3.2.2 Each secondary circuit of a safety extra low voltage (SELV)
    supply source (transformer or convertor) shall have overcurrent protection
    (see 6.7.1 and 6.7.2). The overcurrent protection may be either by a
    common protective device, or a protective device for each SELV circuit.
    
    7.9.3.2.3 A protective device shall be readily accessible unless it is built
    into the supply source and is of the automatic resetting type.
    
    7.9.3.2.4 Secondary overcurrent protection is not required where the
    maximum output of the SELV transformer is 50 VA, the secondary circuit
    conductor is at least 1,5 mm2, not exceeding a length of 2,5 m, and at
    least one conductor and its terminals are insulated to prevent a short
    circuit. Amdt 1
    Quote Originally Posted by murdock View Post
    distance from the transfomer to the lamp?
    Can vary but cable must be sized accordingly, see attached table. Also last 200mm must be class H;

    Code:
    7.9.3.3.1.3 At least 200 mm of the conductors leading from an ELV lamp
    holder shall be 180 °C (class H) flexible conductors such as siliconrubber-
    insulated conductors. The lamp holder shall also be suitable for an
    operating temperature of at least 180 °C. Amdt 3
    Quote Originally Posted by murdock View Post
    using a 300 va transformer and sizing the conductors?
    Again see attached table, depends on length.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	untitled1.jpg 
Views:	40 
Size:	62.3 KB 
ID:	1157  

  3. #3
    Suspended
    Join Date
    Oct 2007
    Posts
    2,346
    Thanks
    0
    Thanked 254 Times in 209 Posts
    lets start with components should be mounted in an enclosure and ventilated?

    the question...is the transfomer regarded as being in an enclosure as it is supplied...because if not then i could spend the rest of my working life going around condeming all the installations?

    the second question...twin and earth suppling the transformers on top of the battens or under the battens?

    if on top do they need to be mechanically protected form people climbing and working in the roof?

  4. #4
    Silver Member
    Join Date
    Oct 2009
    Location
    Johannesburg
    Posts
    201
    Thanks
    25
    Thanked 52 Times in 43 Posts
    The roof is deemed a "traffic free" environment. The twin and earth does not have to be suitably stayed, it can just lie on the ceiling. Secure the connections by adding a clip to the wire/on the beam at the point of exit and the point of entry in the length of the cable.

    Transformers has its own specific section in the book, so they fall under their own specific category. I would assume that the black transformer which comes with a small cover that fits over the supply side terminals is fine as is....so is the single 50VA transformers, also have the cover (they are also double insulated if I am not mistaken?).....if using an uninsulated transformer like one you would find in a swimming pool, then I would say no, that must go in an enclosure.
    IJS Installations
    Electrical, Residential Gas and Electric fencing.

Did you like this article? Share it with your favourite social network.

Did you like this article? Share it with your favourite social network.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •