Type B socket

Discussion in 'General Electronics Chat' started by alphacat, Oct 13, 2009.

  1. alphacat

    Thread Starter Active Member

    Jun 6, 2009
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    Hey guys,

    Is the socket on the left matches the Nema 5-15 socket on the right?

    Thanks.

    [​IMG]
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    It makes the same connections, but there is no way to tell if the current ratings match.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Besides the current ratings, it's difficult to tell if the socket on the left is polarized. It looks like both of the "slots" are the same length.

    Look at the NEMA socket; notice that the right "slot" is longer than the left one. The longer slot is connected to Neutral, the short slot is connected to Hot. This is so that appliances with 2-wire cords can be fitted with plugs that will only fit one way. If there are exposed conductive surfaces on an appliance with a 2-wire cord, they'll either be completely insulated from the wires, or connected to the Neutral wire, which typically is within a few volts of ground.
     
  4. electr

    Active Member

    May 23, 2009
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    @beenthere

    What makes a socket to stand X current?
    For example, what makes Nema 5-15 to be able to conduct 15A, in comparison to the Nema 5-30 outlet which can stand 30A?

    @SgtWookie

    Thank you for this great information.
    I'll check it up tomorrow whether the socket is polarized or not, and will post it up here.
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
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    The internal construction has everything to do with the socket's current rating. The manufacturer will have the rating located on the socket.

    From the photos, both sockets are polarized. Both have the larger slot for AC common.
     
  6. alphacat

    Thread Starter Active Member

    Jun 6, 2009
    186
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    Thanks beenthere!

    Could you please refer me to a link which explain about the internal construction of the socket which sets the current rating?
    I'm very interested in this.

    One more thing about the current rating please.
    You said that there is no way to tell if the current ratings match.
    But isnt the current rating is also set by the slots' polarization?
    For example:

    [​IMG]
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
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    Slight confusion on term "polarization". I consider an outlet polarized if the power slots are differently sized, so a plug may only be inserted in one orientation.

    Your example of the 120 VAC 20 amp outlet with the neutral blade horizontal makes the set (male and female) distinctly different from the 15 amp outlets.

    Internally, the contacts for 20 amp service will be somewhat more robust than for 15 amps. It does not set the capacity, it enables more current capability.
     
  8. alphacat

    Thread Starter Active Member

    Jun 6, 2009
    186
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    Thanks,

    So how come you said that the the outlet in my product could handle less or more than 15Amps?

    I mean, for example, if it was able to handle 20Amps, wouldnt its Neutral slot be horizontal?
     
  9. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,681
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    Having looked at a fair number of wiring devices in the lower current range, say 15 and 20 A, and suspect the internal construction does not vary so much as the arrangement and size of the pins does. The required wire sizes for the different current ranges are different. The pins are arranged differently to prevent someone trying to use a higher current device in a lower current socket. One might assume that the circuit breaker would give protection, and it does, but it the change in the sockets is added protection from doing it accidentally.

    Just as important as the current rating, one must also consider the voltage rating. Again, the design changes are not so much that a 110V socket can't handle 220 volts, but they are to prevent someone from plugging a 110V device into a 220V socket.

    At the higher current end, say 30 to 50A, there are obvious changes in the size of contacts and manner in which wires are attached compared to the lower current devices. For example, you cannot connect a 6AWG wire to a 20A socket, but you can to a higher, properly rated socket. In fact, aftermarket plugs for those device allow the installer to change the contact orientation. Thus, one plug may be used for outlets with different ratings.

    McMaster-Carr has a good section on sockets and plugs. The various code books for household wiring also have good descriptions. Hopefully this link will take you directly to the McMaster section: http://www.mcmaster.com/#about-nema-style-straight-blade-connectors/=42zesr

    If it doesn't, go to mcmaster.com and search on "About NEMA-style Straight-blade Connectors."

    My comments apply only to household wiring in the USA.

    John
     
  10. alphacat

    Thread Starter Active Member

    Jun 6, 2009
    186
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    Thank you very much John! :)
     
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