Cable Size|
Wire Gauge | Current Capacity
Amperage (amps) | Max Voltage |
| 1/0 | 350 | 350 |
| 2 | 225 | 225 |
| 4 | 150 | 150 |
| 6 | 125 | 125 |
| 8 | 100 | 100 |
| 10 | 60 | 60 |
| 12 | 40 | 40 |
| 14 | 25 | 25 |
| 16 | 15 | 15 |
Cross reference
of AWG (American Wire Gauge)
sizes to metric (mm)
|
AWG |
mm2 |
Ohms per km
R per KM | Ohms per 10 ft
R per 10 ft |
| 16 | 1.5 | 13.0 | 0.039624 |
| 14 | 2.5 | 8.54 | 0.02602992 |
| 12 | 4.0 | 5.4 | 0.0164592 |
| 10 | 6.0 | 3.4 | 0.0103632 |
| 8 | 10 | 2.2 | 0.0067056 |
| 6 | 16 | 1.5 | 0.004572 |
| 4 | 25 | .8 | 0.0024384 |
| 2 | 35 | .5 | 0.001524 |
| 1 | 50 | .4 | 0.0012192 |
| 1/0 | 55 | .31 | 0.00094488 |
| 2/0 | 70 | .25 | 0.000762 |
| 3/0 | 95 | .2 | 0.0006096 |
| 4/0 | 120 | .16 | 0.00048768 |
Ohms at 10 feet calculation .003408 x ohms/km
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DC resistance
As long as the current density is totally uniform in the conductor, the DC resistance R of a conductor of regular cross section can be computed as
Where:
l is the length of the conductor, measured in meters
A is the cross-sectional area, measured in square meters
p(Greek: rho) is the electrical resitivity (also called specific electrical resistance)
Copper Electrical resistivity (microohm/cm)
1.678
Ohms of resistance in a material can be measured by a multimeter over a wire. Resistance is a measure of the material's ability to oppose the flow of electric current.
For practical reasons, almost any connection to a real conductor will not show perfect current density, or is not totally uniform. However, this formula still provides a good approximation for long thin conductors such as wires.
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AC & DC Voltage Drop Over Length of Wire Calculator
The following calculator calculates the voltage drop, and voltage at the end of the wire for American Wire
Gauge from 4/0 AWG to 30 AWG, aluminum or copper wire. (Note: System calculates ANY voltage drop, whether safe or not. CONSULT your local, city, state, and national electrical code or your electrician to decide what is legal before building!
Calculate Voltage Drop in WireTo calculate voltage drop, plug in the values: V = DIR/1000
Where I is the amperage,
R is from the ohms/10' X 100 column left,
and D is the total distance the current travels
(don't forget to add the length of the neutral and hot together - ie: usually double cable length). Design rules in the CEC call for a maximum voltage drop of 6% (7V on 120V circuit).
Cool Wire Tricks
The wire gauge is a logarithmic scale base on the cross sectional area of the wire. Each 3-gauge step in size corresponds to a doubling or halving of the cross sectional area. For example, going from 20 gauge to 17 gauge doubles the cross sectional area (which, by the way, halves the DC resistance).
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