Table of Contents
There are the three use-cases for electrical wires :
Hot or Live = This is the source of electricity. Handle this wire with caution. It is recommended to disable the power source, if possible, when handling this wire.
Neutral = This completes an electrical circuit. It will only have power if a hot/live wire is connected.
Ground = For when the power may be unstable, power is redirected through this wire and literally into the ground to dissipate the energy.
Wires have two physical types :
Solid = A single piece of wire.
Easier to solder.
Easier to break.
Easier to insert into holes and terminal connectors.
Stranded = A collection of smaller wires combined.
Harder to solder.
Harder to break.
Harder to insert into holes and terminal connectors.
A gauge is how thick a wire is. The lower the number, the bigger the thickness. Here are recommendations for what gauge wire to use based on the project:
Breadboard, Arduino, Raspberry Pi, and other single-board devices. 
House lights. 
Small appliances. 
House in-wall electrical wiring. 
Speakers that require high power consumption and/or long wires. 
Each country has a different standard for the purpose of each colored wire. In the United States of America, these are the standards :
Red = High voltage up to 240 volts.
Orange = Very high voltage up to 480 volts.
White = High voltage up to 240 volts.
Grey = Very high voltage up to 480 volts.
Bare wire (no covering)
A relay is a switch that controls power being sent through a wire or circuit. It is either normally open (NO) or normally closed (NC) when there is power sent through a contact in relay. When there is no power through a contact, a NO gate will turn off and a NC gate will turn on.
There are two types of relays: electromechanical relays (EMR) and solid-state relays (SSR). EMR uses magnets to move a physical switch. SSR uses circuits to direct electricity.
State of the relay is more reliable.
It is either on or off.
Requires more power to change the state.
More likely to break.
State of the relay is less reliable.
It is somewhere between on and off but leans towards one or the other.
Requires less power to change the state.
Less likely to break.
No moving parts.
“How Relays Work.” Galco. Accessed September 24, 2021. https://www.galco.com/comp/prod/relay.htm
“Wiring Color Codes Chapter 2 - Color Codes.” All About Circuits Electrical Textbook. Accessed May 8, 2022. https://www.allaboutcircuits.com/textbook/reference/chpt-2/wiring-color-codes-infographic/
“Electrical Wiring Tips: What is Hot, Neutral, and Ground.” Roman Electric. Accessed May 8, 2022. https://romanelectrichome.com/electrical-wiring-tips/
“Stock Up on Wire for Your Electronics Projects.” dummies. March 26, 2016. Accessed May 8, 2022. https://www.dummies.com/article/technology/electronics/general-electronics/stock-up-on-wire-for-your-electronics-projects-180328/
“Fix a Lamp Cord.” Family Handyman. August 28, 2019. Accessed May 8, 2022. https://www.familyhandyman.com/project/fix-a-lamp-cord/
“What Size Speaker Wire Is Right? The Right Gauge, Type, And More.” Sound Certified. April 10, 2022. Accessed May 8, 2022. https://soundcertified.com/what-size-speaker-wire-guide/