about the safety of a power plug 2 prongs

Discussion in 'General Electronics Chat' started by mikelynch, Aug 7, 2014.

  1. mikelynch

    Thread Starter Member

    Jun 30, 2007
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    I was reading the first thread/posts this forum has about ohms law and safety. It tries to explain to me the use of the third prong to earth in a power plug. And if the plug you have has 3 prongs and the receptor power port on the wall or cord only has two slots, do not cut the ground plug ie. the third pin. because if their is something wrong in the device, a short it could cause you to be the receiver of a dangerous shock travelling through you instead of the earth plug which you cut off to make the plug fit.

    So then why is it my soldering iron only has two prongs, I don't have to cut the third earth prong because there is none on my 60watt solder iron.

    Is my solder iron then more dangerous to use than one I could have purchased with the three prongs ?

    PS. My solder iron is a piece of rubbish. Its way too hot. I have to unplug it often and let it cool down before I plug it in to do some more brief soldering :D
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,440
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    There are three separate questions in your post that deserve three separate answers.

    1) Risk of electrocution
    Low cost products use 2-pin plugs to save money. In the case of a soldering iron, if there ever is a short between the body of the iron and the live side of AC mains your iron becomes a lethal tool.

    2) Electrostatic buildup
    A tool that is not grounded could develop a high voltage that can damage sensitive semiconductor components.

    3) Unregulated temperature
    A low cost soldering iron is handy for doing quick soldering jobs around the home and workshop. For electronic work, get a temperature controlled soldering iron.
     
  3. alfacliff

    Well-Known Member

    Dec 13, 2013
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    get a light dimmer from the hardware store, put it in a double gang box with a receptical, that will allow you to control the temprature.
    a company I worked for years ago went to 3 pin plug soldering irons for safety and antistatic. after a while, they would short internally and blow a chunk out of the side of the iron. maybe the newer irons have been improved, there are now a lot of three pin irons available.
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,387
    1,605
    Once upon a time hand tools and such came with metal cases connected to the third prong earth ground.

    Then it became the norm to build tools with plastic cases, so to lessen the safety impact the concept of “double insulated” was employed, where each wire is insulated inside the insulated (plastic) housing. Thus only a two prong plug was necessary.

    One would hope your iron is built on the “double insulated” scheme.
     
  5. studiot

    AAC Fanatic!

    Nov 9, 2007
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    They are indeed better insulated than normal tools, (many boast femtoamps leakage)

    But how would you 'double insulate' a heater device?
     
  6. alfacliff

    Well-Known Member

    Dec 13, 2013
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    and how to make sure the insulation would work with repeated heating cooling cycles? that was the problem at NCR, the ceramic insulation failed, leading to a mini arc blast.
     
  7. crutschow

    Expert

    Mar 14, 2008
    13,006
    3,232
    I would say that, in general, a soldering iron without a transformer connected directly to the wall without a safety ground is a shock hazard. You can mitigate the danger by only plugging it into a GFI outlet. That way any significant leakage current to earth ground will trip the GFI breaker.

    If your iron is too hot then it likely has too high a power rating for electronic work.
     
  8. studiot

    AAC Fanatic!

    Nov 9, 2007
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    The tip will also burn out too quickly.

    I recall a hobby design for a soldering iron bench stand incorporating a wire hook connected to a microswitch.

    When you hung the iron on the hook it switched a power diode into series with the supply, halving the input power, saving the tip and keeping the iron on warm standby.
     
    Last edited: Aug 7, 2014
  9. mikelynch

    Thread Starter Member

    Jun 30, 2007
    23
    0
    This is a great sounding way of making the iron work a lot better. So long as the hardware store sells at a reasonable price. I could get a new iron pretty cheaply. but thanks.
     
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