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Is it wrong to leave a transformer plugged in ??

Discussion in 'General Electronics Discussion' started by Al Slitter, Dec 27, 2018.

  1. Al Slitter

    Al Slitter

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    Nov 4, 2016
    I just installed in our home a set of strip lighting under our kitchen cupboards. The lights are 5630 LED's and are approximately 2.2 meters long. I wired the 12 volt 5 Amp transformer directly into mains and have a single pole switch controlling the DC current to the strip lighting.
    All seems fine and the wife is happy with the lighting.
    I was thinking about this last night and am wondering if I should have installed a breaker as a switch so as to shut off the current to the transformer instead?
    I would greatly appreciate your opinion.

    I have shown the transformer below:

    Transformer.png
     
  2. Bluejets

    Bluejets

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    Oct 5, 2014
    This could mean many different things depending on your perception of wiring etc.
    In some countries it is illegal ...firstly to do your own mains wiring and secondly to install anything without required protection and an isolator of some description.
    Check with you local lecky .........best bet.

    Ah,....just noticed "Thailand". :eek:
     
  3. BobK

    BobK

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    Jan 5, 2010
    That is not a transformer, it is a switching power supply. Switching the AC input would conserve energy. How much is anybody's guess unless you have specs for the idle current taken by the power supply. If you have a kill-a-watt you could find out. If you do put in an AC switch, make sure all the wiring is enclosed and the switch is rated for AC line voltage. I think it would only be illegal if you were installing wiring in the walls, if it plugs in to an existing outlet it should be OK.

    Bob
     
  4. Bluejets

    Bluejets

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    Oct 5, 2014
    Just realised you may be concerned with it continually powered up.(from a deterioration point of view)
    Not the best idea but then again, every tv, dvd etc etc have the same arrangement as far as power supplies go and people leave these switched on, idling for years on end.
    Would tend to dry out electrolytics etc and shorten the life to a degree.
     
    Last edited: Dec 28, 2018
  5. Minder

    Minder

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    Apr 24, 2015
    As mentioned, that would be a SMPS and in many cases has an internal fuse, maybe pay to check.
    M.
     
    Cannonball likes this.
  6. Al Slitter

    Al Slitter

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    Nov 4, 2016
    Thanks all for the replies.
    Yes the issue has to do with deterioration of the power supply and yes it is a switching power supply.
    Being retired here in Thailand I find it humorous how some try and use first world safety concerns when it applies to
    this country.
    I have gone to great lengths to modify our home to have it be more safe.

    Thanks all and a Merry Christmas.
     
  7. Externet

    Externet

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    Aug 24, 2009
    Where is the supply installed? If reachable, a switch can be installed at an aluminium end 'wing' to cut off the mains input instead of the output.
    Mine are under the upper kitchen cabinets with mains switch added.
     
  8. Audioguru

    Audioguru

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    Sep 24, 2016
    Most safe electrical products I have seen have a manufacturer's name on the spec's label. This power supply is hiding the name like the defective compact fluorescent light bulbs that were given out then recalled because they dripped flaming plastic.

    Seeing the missing manufacturer's name and the country it is from I would never leave it powered all the time and not use it.
     
    Cannonball likes this.
  9. Bluejets

    Bluejets

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    Oct 5, 2014
    If one did this in Thailand, one would never have an electrical device.
    Mai phen rai ......
     
  10. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    I find it humorous that you say that, then indicate you have the same concerns.

    Not too many of us will think "Oh, he's in Thailand, I'll give him worse advice than I would to someone in another country."
     
  11. Al Slitter

    Al Slitter

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    Nov 4, 2016
    Hello Externet;
    The switching power supply is located up on top of the upper cupboards.
    I have a 16 gauge stranded cable running to a switch mounted under the upper cabinets for ease of use.
    Changing the wiring and switch to facilitate power to the transformer is doable and will require a bit of effort
    but might be the best solution.
    I need to think about this???
     
  12. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    My advice would be to install a separate switch to remove mains power from the power supply. If it is already plugged into a wall outlet then that is sufficient. Even if you don't turn it on and off at this switch, you do have the capability of isolating the power supply if you need to (similar to a TV set plugged into a wall, you can turn it off or unplug it if you have the need).

    I have a similar arrangement for low voltage lighting in my shed. The LEDs are driven by a couple of small constant current drivers connected to an AC plugpack. There are switches to allow me to turn the various lights on and off independently, but I also have a switch to remove power from the plugpack. Whilst I consider it safe to leave the plugpacks connected 24x7, they are not easily visible and I don't live in my shed, so I want the capability to turn *everything* off when I lock up the shed. Also, if there's a fault, I don't want to be in the position of having to use the breaker for my entire shed just to isolate a couple of low voltage lights.

    In my case, I have used standard light switches to switch my low voltage lights (so they look like normal light switches) and a separate switch to turn the low voltage on and off (by switching mains to the unswitched outlets)

    1546045946757168.jpg

    The switch on the upper right is the main fluorescent light. The switches on the upper left are for two independent LED strips (and are switching 15VAC and under 100mA). The middle switch on the dual switched outlet (lower right) switches power to an unswitched single outlet (not visible) where the transformer is plugged in.

    For those concerned with the proximity between the two sets of light switches, they are either side of a vertical member of a stud wall. And for those interested in lighting, yes, this photo was taken using the light from just one of the LED strips at the rear of the shed.

    The fact that I have easy access to and often use the switch doesn't mean you have to. In fact, just being able to unplug the power supply would be sufficient. However it may be simpler to place a switch somewhere.
     
    Cannonball likes this.
  13. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    Personally, I've seen too many cheap Chinese products like this smoke/catch fire to trust mounting it near anything combustible like under your cabinet.

    I also wouldn't necessarily trust the CE mark with out verifying it. They are notorious for faking testing agency listings.

    [Mod edit: I wish I could like this post more than once]
     
    Last edited by a moderator: Dec 30, 2018
    (*steve*) likes this.
  14. Bluejets

    Bluejets

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    Oct 5, 2014
    Thing is, in Thailand they make the kitchen cabinets and the tops etc from concrete and tile.

    Do a really nice job of it too I might add.
     
  15. Al Slitter

    Al Slitter

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    Nov 4, 2016
    Hello Steve, you gave me exactly what I needed to know.

    Thank you!
     
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