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Understanding Electrical Circuits

An electrical circuit is a continuous loop. Household circuits carry electricity from the main service panel, throughout the house, and back to the main service panel. Several switches, receptacles, light fixtures, or appliances may be connected to a single circuit.

The Complete Guide to Electrical Wiring (Current with 2014–2017 Electrical Codes) by Black+Decker
The Complete Guide to Electrical Wiring (Current with 2014–2017 Electrical Codes) by Black+Decker

Current enters a circuit loop on hot wires and returns along neutral wires. These wires are color coded for easy identification.

Hot wires are black or red, and neutral wires are white or light gray. For safety, all modern circuits include a bare copper or green insulated grounding wire. The grounding wire conducts current in the event of a ground fault and helps reduce the chance of severe electrical shock.

The service panel also has a bonding wire connected to a metal water pipe and a grounding wire connected to a metal grounding rod, buried underground, or to another type of grounding electrode.

Electric circuits of lighting
Electric circuits of lighting

If a circuit carries too much current, it can overload. A fuse or a circuit breaker protects each circuit in case of overloads. Current returns to the service panel along a neutral circuit wire. Current then leaves the house on a large neutral service wire that returns it to the utility transformer.


Grounding and Polarization

Electricity always seeks to return to its source and complete a continuous circuit. Contrary to popular belief, electricity will take all available return paths to its source, not just the path of lowest resistance.

In a household wiring system, this return path is provided by white neutral wires that return current to the main service panel. From the service panel, current returns along the uninsulated neutral service wire to a power pole transformer.

You will see the terms grounding and bonding used in this and other books about electricity. These terms are often misunderstood. You should understand the difference to safely work on electrical circuits.

LEFT: Normal current flow; RIGHT: Current is detoured by a loose wire in contact with the metal box.
LEFT: Normal current flow – Current enters the electrical box along a black hot wire and then returns to the service panel along a white neutral wire. RIGHT: Current is detoured by a loose wire in contact with the metal box. The grounding wire and bonded metal conduit pick it up and channel it back to the main service panel, where the overcurrent device is tripped, stopping further flow of current. Most current in the bonding and ground system flows back to the transformer; some may trickle out through the copper that leads to the grounding node.

Bonding connects the non-current-carrying metal parts of the electrical system, such as metal boxes and metal conduit, in a continuous low-resistance path back to the main service panel. If this metal becomes energized (a ground fault), current travels on the bonded metal and quickly increases to an amount that trips the circuit breaker or blows the fuse.

The dead circuit alerts people to a problem.

Title:The Complete Guide to Electrical Wiring (Current with 2014–2017 Electrical Codes) – Black+Decker
Format:PDF
Size:44.8 MB
Pages:339
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The Complete Guide to Electrical Wiring (Current with 2014–2017 Electrical Codes) – Black+Decker
The Complete Guide to Electrical Wiring (Current with 2014–2017 Electrical Codes) – Black+Decker

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33 Comments


  1. OYILO ROBERT
    Feb 21, 2024

    thank’s sir/madaam,i have understood what you have tought or written down,my question is the wirig of merterbox through the pole upto the housepart


  2. Rafael M Polanco
    Sep 30, 2023

    Thank you! I appreciate the information I found in this portal. I want to self- educate and -train in electrical circuit and beyond. I could use all the help I can get.


  3. Nonso iyaji
    Sep 28, 2023

    Thanks for your help and I also won to learn more on house wiring thanks


  4. Famous Ovueferaye
    Aug 17, 2023

    Thanks for this enlightenment, I want to learn more in house wiring


  5. yusuf ahmadu
    Mar 27, 2023

    I want learn electrical engineering


  6. Elmutasim Mohamad
    Feb 19, 2023

    would like to thank you all that usefully information you provided, that efforts really appreciated,


  7. Johan Schoeman
    Jan 23, 2023

    I would like to understand the rules of housewiring as well as the Safety aspects of electrical circuits.


  8. Muhammed Olu
    Jan 14, 2023

    Interested please


  9. Win Magtuba
    Jan 05, 2023

    Wanted to know about Electrical House Wiring.


  10. Bol
    Dec 13, 2022

    Am interested in this book for my work day please


  11. Johnoliba
    Jun 12, 2022

    I want to self study electrical engineering.


  12. a muthaiah
    Jun 07, 2022

    i need to study electrical circuits


    • ogolo godwin
      Nov 24, 2023

      I’M godwin ogolo by name, i away’s wanted to be an electrical engineer, and i promised myself to pursue my dream, i have experience on electrical


  13. PURUSHOTHAM
    Apr 08, 2022

    i want to
    learn


  14. Ian Clarke
    Mar 31, 2022

    wiring a switch with power to the light first. We can no longer use the neutral as a power wire as neutral cannot be sacrificed here. Can I simply run three-wire for this configuration?


  15. K.M.W. Bandara
    Nov 23, 2021

    a valuable book for aspiring technicians


  16. dana
    Sep 21, 2021

    can i get a copy to make sure i dont catchj anything i invent or build on fire please? its purple in deert again so i could advertise ya….. thanks.


  17. EBENEZER
    May 26, 2021

    Hi,l want to upgrade my electrical skills both theory and practical can l have a company to work with to enable me have more experience?


  18. ededeh mgbowa marshall
    Apr 11, 2021

    i will like to be getting lessons on power systems and electronics from you , thanks


  19. Nwankwo Isaiah
    Jan 14, 2021

    Please I want to learn electrical wiring and electrical design. Pls can someone help me out?


  20. Nwankwo Isaiah
    Jan 14, 2021

    Pls I need a professional to teach me Electrical Installation.


  21. Bobby Barlow
    Nov 11, 2020

    I have a photoelectric switch with a “load” wire. What is it for?.


    • Ben
      May 22, 2021

      That goes to whatever the switch controls e.g. a light


  22. Arjon
    Oct 15, 2020

    Very helpful,I would like to get many articles as possible to go deep into electronics.


  23. Pelumi
    Aug 18, 2020

    I want to learn


  24. Renston Young
    Jun 04, 2020

    Mornings how do i get a copy of the complete 101 diagram book


  25. craig gremillion
    Apr 07, 2020

    i been electrican for 44 yrs. need online literature to train personnal on line


    • mahmoud
      Jul 23, 2020

      I want learn


  26. Taiwo Adewale
    Dec 31, 2019

    How can I be trained to be come a perfect electrical house wiring


  27. Bimsara sandeepa
    Nov 07, 2019

    I want learn


  28. innocent mathew ulomi
    Oct 20, 2019

    I what to know how to be plan any electrical design on wiring


  29. Yasser
    Jul 31, 2019

    Good work


  30. Aqil Akhtar
    Feb 22, 2017

    Hi can you recommend a book for basic domestic electrics and wiring. Im starting from very basics… how wiring works and how to wire home appliances up. The only thing i know right now is how to wire a plug and thats with copying the diagram on the top. Thank you.Aqil, UK

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