Tamaño de conductor
Los conductores vienen en tamaños estándar según la ubicación. El tamaño de conductor adecuado para un circuito en particular depende de dos consideraciones importantes:
- La cantidad de corriente que pueden transportar de forma segura según las condiciones en las que se utilizarán. Las condiciones de uso que se deben considerar incluyen: la cantidad de cables en el conducto, la temperatura ambiente máxima y el tamaño adecuado del dispositivo de protección contra sobrecorrientes.
- La cantidad de voltaje que se perderá durante el funcionamiento, que se denomina caída de tensión
The wires for an off-grid system must will be sized and selected based upon the load evaluation and the physical evaluation for a particular site. This process must be done in conjunction with the sizing and selection of an overcurrent protection device for the circuit - see Dimensionamiento y selección de cables, protección contra sobrecorrientes y medios de desconexión for more information.
The two most common standards for conductor size are American Wire Gauge (AWG) and mm². These two systems are not directly equivalent. The table below shows conductor sizes in AWG and mm² with the ampacity (maximum current) rating of depending upon its temperature rating of the conductor in °C. This chart assumes that there are are 1-3 copper conductors in conduit with a 30°C ambient temperature.[1] These values must be adjusted for the actual conditions of use of the conductor.
60°C | 75°C | 90°C | |||
---|---|---|---|---|---|
AWG size | Area (mm²) | Metric equivalent (mm²) | Types TW, UF | Types RHW, THHW, THW, THWN, XHHW, USE, ZW | Types TBS, SA, SIS, FEP, FEPB, MI, RHH, RHW-2, THHN, THHW, THW-2, THWN-2, USE-2, XHH, XHHW, XHHW-2, ZW-2 |
14 | 2.08 mm² | 2.5 mm² | 15 A | 20 A | 25 A |
12 | 3.31 mm² | 4 mm² | 20 A | 25 A | 30 A |
10 | 5.26 mm² | 6 mm² | 30 A | 35 A | 40 A |
8 | 8.37 mm² | 10 mm² | 40 A | 50 A | 55 A |
6 | 13.3 mm² | 16 mm² | 55 A | 65 A | 75 A |
4 | 21.2 mm² | 25 mm² | 70 A | 85 A | 95 A |
3 | 26.7 mm² | — | 85 A | 100 A | 110 A |
2 | 33.6 mm² | 35 mm² | 95 A | 115 A | 130 A |
1 | 42.4 mm² | 50 mm² | 110 A | 130 A | 150 A |
1/0 | 53.5 mm² | — | 125 A | 150 A | 170 A |
2/0 | 67.4 mm² | 70 mm² | 145 A | 175 A | 195 A |
3/0 | 85 mm² | 95 mm² | 165 A | 200 A | 225 A |
4/0 | 107 mm² | 120 mm² | 195 A | 230 A | 260 A |
Cable size
Cables are typically designed to contain all of the wires that are needed for a particular circuit. Therefore there are many different configurations of cable that vary based upon the size of the wires, the number of wires, and the color of the wires. Cables will be labeled with the size of the current carrying conductors and the quantity. For example a cable with three 12 AWG wires will be labeled "12/3". A cable with three 2.5mm² will be labeled "2.5mm²/3" or "2.5mm² three core". Equipment grounding conductors (EGCs) are generally excluded from the count of conductors and should be specified separately.
Notes/references
- ↑ NFPA 70 - National Electrical Code 2020: Table 310.15(B)(16)