What is the Amperage Rating of a 3-Pronged Edison Plug

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    Amperage Rating
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Discussion Overview

The discussion revolves around the amperage rating of a standard three-pronged Edison plug and the associated ratings of common house wiring. Participants explore the implications of these ratings in practical scenarios, including safety considerations and circuit design.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant believes that a three-pronged plug is rated at 15 amps and that house wiring should be able to carry at least that amount, leading to a calculation of 1800 watts at 120 volts.
  • Another participant confirms that most circuits in buildings typically carry 15 or 20 amps, noting that exceeding this will trip circuit breakers.
  • A different participant points out that multiple outlets are usually connected to the same breaker, suggesting a design consideration of limiting the number of outlets per circuit based on expected usage.
  • One participant references electrical code, stating that the rating of cord and plug-connected equipment should not exceed 80 percent of the branch circuit rating, and highlights the need for higher ampacity for continuous loads.

Areas of Agreement / Disagreement

Participants generally agree on the standard ratings for plugs and circuits, but there are differing views on the implications of these ratings in practical applications, particularly regarding circuit design and safety measures.

Contextual Notes

There are limitations in the discussion regarding assumptions about circuit design, the number of outlets per circuit, and the specific conditions under which the ratings apply. The discussion does not resolve these complexities.

Juxt
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I know this isn't quite what you mean when you say electrical engineering, but, how many amps is a standard three-pronged edison plug rated at? Also, what is common house wiring rated at?

I believe that a three-pronged plug is rated at 15 amps and that logically the wiring should be able to carry at least that. By my calculations then in the US with good ol' 120-volts you should be able to carry 1800 watts on a wall outlet.

I'm just a layman at electricity and I just wanted to be sure. As much as some people dream about it I don't want to burn down my school.
 
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You're correct, most circuits in most buildings will carry 15 or 20 amps. If you try to pull more than that, you'll just pop the circuit breakers.

- Warren
 
Originally posted by Juxt
By my calculations then in the US with good ol' 120-volts you should be able to carry 1800 watts on a wall outlet.
Yes, but as you know, generally more than one outlet goes to the same breaker. When designing a building, you put a maximum of 10 outlets (depending on known usage) on a circuit and assume 180w per outlet.
If you know (for example) that an outlet supplies power to a window air conditioner, you put it on its own circuit.
 
Right Russ. Code says "The rating of anyone cord and plug-connected utilization equipment shall not exceed 80 percent of the branch circuit ampere rating. Fixed in place equipment shall not exceed 50 percent where lighting and convenience outlets are also supplied". On anything with a continuous load (3 hours or more) ampacity should be at least 125 percent of full load rating of the equipment.(like heat, air conditioning, motors, etc...) Please be careful.
-Mike
 

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