Conductor types

Wire and cable connects allows the safe transport of electricity between all of the different components of an electrical system. Wire refers to a single conductor whereas cable contains various different conductors within an additional layer of insulation. The proper size of wire for a cirucit depends upon:

1. Wire ampacity - which is the amount of current that it can safely carry under the conditions without overheating.
2. Voltage drop - which is the percentage of voltage that is lost when the circuit is operating.

Wires for use in electrical systems are made of copper or aluminum, but for offgrid applications copper is almost universally used as it can carry more current for the same wire size and is more flexible.

Size

Wires come in standard sizes that are linked to the amount of current that they can safely carry (see wire ampacity). The two most common standards for wire size are American Wire Gauge (AWG) and mm². These two systems are not directly equivalent.

Standard AWG	Metric equivalent	Standard metric equivalent (mm)
18AWG	.82mm²	1mm²
16 AWG	1.31mm²	1.5mm²
14 AWG	2.08mm²	2.5mm²
12AWG	3.31mm²	4mm²
10 AWG	5.26mm²	6mm²
8 AWG	8.37mm²	10mm²
6 AWG	13.3mm²	16mm²
4 AWG	21.2mm²	25mm²
3 AWG	26.7mm²
2 AWG	33.6mm²	35mm²
1 AWG	42.4mm²	50mm²
1/0 AWG	53.5mm²
2/0 AWG	67.4mm²	70mm²
3/0 AWG	85mm²	95mm²
4/0 AWG	107mm²	120mm²

Color coding

Different wire color schemes.
IEC/NEC AC circuits from top to bottom: L1, L2, L3 refer to ungrounded current carrying conductors. N refers to grounded current carrying conductors. G refers to protective grounding system.
DC circuits from top to bottom: Ungrounded positive, ungrounded negative, grounded conductor, and protective grounding system.

Wires can come with insulation (used for carrying current in a circuit) or without insulation ([[Grounding system|grounding system). If the wires have insulation, it will be possible to choose from a variety of different colors each of which is used to signify the purpose of that wire within an electrical installation. The standards vary from country to country, therefore it is necessary to research the practices in your location. Additionally, the appropriate colors will vary in each country depending upon whether the circuit is AC, DC and its nominal voltage.

IEC standard for residential AC wiring

• Phase 1 - Brown
• Phase 2 - Black
• Phase 3 - Grey
• Neutral - Blue
• Ground - Green with Yellow Stripe/without insulation

US NEC standard for residential 120/208/240 AC wiring

• Phase 1 - Black
• Phase 2 - Red
• Phase 3 - Blue
• Neutral - White or grey
• Ground - Green/Green with yellow/without insulation

Standard for DC wiring in PV systems

• Positive - Red
• Ungrounded negative - Black
• Grounded negative - White or grey
• Ground - Green/Green with yellow/without insulation

Wire types

   T – Thermoplastic insulation  
   H – Heat resistant  
   HH – High heat resistance up to 194-degrees Fahrenheit  
   W – Rated for wet locations  
   N – Nylon-coated to resist damage from oil or gasoline 
   X – Synthetic polymer, flame-resistant