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Power supply w/o ground

Discussion in 'Electronic Basics' started by JT, Sep 24, 2007.

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  1. JT

    JT Guest

    A small open-frame line powered power supply (Cincom CFM05S033) doesn't have
    a ground connection. It will power a tiny device which only has +3.3V/0V DC
    connections. This will be used in a 6x6x4 plastic enclosure so there is no
    chassis ground. An electrician will be wiring it in.

    Is this inherently unsafe? Do I need to find another supply with a ground?
     
  2. Charles

    Charles Guest

    I assume you are asking about Earth Grounds. Some devices operate safely
    with them. You should be go to go ... but it depends on worst cases and
    possible litigation.
     

  3. WTH is 'go to go'? It's time to up your meds, again. ;(


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  4. Eeyore

    Eeyore Guest

    Where did you expect to see a GROUND and why ?

    Plenty of power supplies don't have them and don't need them. See Class II
    insulation.
    http://en.wikipedia.org/wiki/Appliance_classes

    Graham
     
  5. Chris

    Chris Guest

    The AC-to-DC switching regulator power supply you're using has an
    isolated output, meaning it's constructed so there's no inherent
    connection between either the positive or negative end of the 3.3VDC
    supply and anything else.

    Actually, the data sheet suggests there's more than 4KV isolation
    between the line voltage input side and the output. I'd take that
    with a grain of salt, but it does tell you there's no inherent danger
    involved in either leaving the supply output floating, or grounding
    it.

    If you need a grounded supply (think twice before doing this unless
    you have to -- most times, in industrial applications grounding the
    supply causes more difficulty than it solves), you can just connect
    the earth ground wire to the negative terminal of the supply (or the
    positive terminal, for that matter).
     
  6. Surely the Great Terrell can figure that out?
     
  7. Phil Allison

    Phil Allison Guest

    "JT"

    ** The brand name is " Cincon " - you PITA.





    ........ Phil
     
  8. Phil Allison

    Phil Allison Guest

    "Chris"

    ** Mere isolation voltage figures tell you .......

    NO SUCH DAMN THING !!

    A given product is either made to meet "Class 2 " ( ie double insulation)
    safety requirements or it is NOT !!

    If it is NOT - then all user accessible wiring & exposed metal MUST be
    connected to safety ground via a solid wire link.

    If a product does not specifically state that it meets all Class 2
    ules - NEVER assume.

    Someone's life may be on the line.




    ........ Phil
     
  9. JT

    JT Guest

    I am not building a double-insulated Class II device. It is a power supply
    in a IP65 plastic enclosure, it can potentially be LOCATED OUTSIDE.

    This "Cincon" (sorry Phil if I offended you.???) supply only has 2 tiny pads
    exposing the 120VAC to the user, I will cover these with epoxy potting
    compound.

    Class I says the chassis should be grounded but the chassis is plastic.
    There will be an Earth Ground line coming in, should I just connect it to
    the AC Neutral terminal?

    Or, is this supply specifically design for Class II and I need to find
    another?
     
  10. Phil Allison

    Phil Allison Guest

    "JT"

    ** Sure sounds the hell like you ARE to me !!!

    Got a clue what one is ??




    ** Nonsense.

    External PSU are nearly all required to be Class 2 devices

    - by LAW !!!

    Take a look at any wall wart or phone charger.



    ** Your dumb spelling error wasted my time on Google.



    ** Class 1 requires any output connection to be safety EARTHED !!!!!!!!!



    ** Read my post.

    If there are no marking re Class 2 compliance

    - it damn well AIN'T !!!!!!!!




    ........ Phil
     
  11. JT

    JT Guest

    "Phil Allison"
    Please clarify "external PSU". You imply...external to the product, like a
    wall wart. My design will have the PSU internal to the product. The entire
    product and PSU is in the IP65 housing, there are no other connections or
    outputs. So I think I am still looking at a Class I device, correct?
    There are no "outputs".
    There will be an Earth Ground conductor coming in, should I just connect it
    to
    the AC Neutral terminal?
     
  12. Phil Allison

    Phil Allison Guest

    "JT"
    "Phil Allison"

    ** Your " located outside " will do anytime

    - FUCKWIT !!!!!!!!!!!!!!!!!!!!!.



    ** Now * I KNOW * you are fuckwit * LIAR * .




    ** Nothing at allllllll ???

    No user accessible metal parts whateverrrrrrrrr ????

    So it does nothing and connects to nothing ???????????


    LIKE HELL !!!!!!!!!!!!



    ** I reckon you are staring right up you hairy, fat arse.

    As usual.



    ** Why ?????????????????????????????????????


    ** If you wanna trip every stinking single ELCB, Core Balance Relay,
    Safety Switch and RCD in the entire fucking world.

    Yeah - go do that.

    IMBECILE !!!!!!!!!!!




    ....... Phil
     
  13. JT

    JT Guest

    Nice grammar, I haven't a clue what you just said.
    The entire product and PSU are in the IP65 housing, THERE ARE NO OTHER
    CONNECTIONS OR OUTPUTS.
    You saw the picture. Sure, the power supply has "metal parts", if you're
    counting component leads and solder pads. Your point?
    If I don't need an Earth Ground just say so.
    ....hence my questioning of this suggetion from "Chris".
     
  14. JT

    JT Guest


    Perhaps someone can suggest how to safely wire and enclose a small 3.3V
    device with 120VAC power supply for use outdoors.
    TIA
     
  15. Phil Allison

    Phil Allison Guest

    "JT"

    ** Totally " pot " the damn thing.

    Polyester resin is top stuff.





    ...... Phil
     
  16. Eeyore

    Eeyore Guest

    If it's not Class II then it's presumably Class I which requires an earth.

    If you need to ask, quite frankly you shouldn't be building anything like this.

    I suggest you read up on safety standards.

    Graham
     
  17. Eeyore

    Eeyore Guest

    Frankly, if you think such an idea is even remotely acceptable you deserve to be
    shot.

    Graham
     
  18. DO NOT connect the earth ground (safety ground, green or green/yellow
    wire) to the neutral in your equipment. The safety ground should be
    connected to any exposed metal (or otherwise conductive) parts of your
    equipment.

    If your device has no exposed metal parts, do not connect the green
    (or green/yellow) safety ground to anything.


    --
    Peter Bennett, VE7CEI
    peterbb4 (at) interchange.ubc.ca
    new newsgroup users info : http://vancouver-webpages.com/nnq
    GPS and NMEA info: http://vancouver-webpages.com/peter
    Vancouver Power Squadron: http://vancouver.powersquadron.ca
     
  19. Eric R Snow

    Eric R Snow Guest

    Why not buy a wall wart with the required output? It will be made to
    be ungrounded and all the energized parts will be enclosed by the
    maker so you won't need to worry. By the way, please don't pay
    attention to phil allison. He is probably in need of professional help
    but instead spends his time trying to rile up anybody he can online.
    Just like when CB radios were a big craze and all sorts of shy whackos
    would get their hands on a radio and broadcast all sorts of stuff
    pretending to be something or someone they were not.
    ERS
     
  20. neon

    neon

    1,325
    0
    Oct 21, 2006
    What is ground just a referebce point. If you want total isolation then transformer is the way to go.
     
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