Contents
- Choosing the correct size cable
- Related Pages
Caution
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Choosing the correct size cable
It is important to choose the correct size cable when connecting to the mains. The wire has to be the correct size so that it can cope with the power demands of the device. The size stated for cables is given in mm2 and this measurement is actually the cross sectional area of the wire inside. The larger that area the higher the current it can carry.
If a cable is used which is too small for the amount of current passing through, it becomes dangerous. This results in the wire overheating and causing a serious safety risk. The table below gives typical values of cable size available plus corresponding current rating and maximum power ratings.
| Conductor Size | Current | Maximum power (Watts) |
| 1.0 mm2 | 10 amps | Up to 2400 Watts |
| 1.25 mm2 | 13 amps | Up to 3120 Watts |
| 1.5 mm2 | 15 amps | Up to 3600 Watts |
| 2.5 mm2 | 20 amps | Up to 4800 Watts |
| 4.0 mm2 | 25 amps | Up to 6000 Watts |
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FAQs
First, measure the highest permissible voltage drop. Second, calculate the load current. Third, you must know that the most appropriate cable will be one that has a current rating closest to the load current calculated. Several charts with cable sizes and corresponding current ratings are easily available online.
How do I calculate what size wire I need? ›
Perform the following calculation to get the cross-sectional area that's required for the wire: Multiply the resistivity (Ω m) of the conductor material by the peak motor current (A), the number 1.25, and the total length of the cable (m). Divide the result by the voltage drop from the power source to the motor.
What is the rule of thumb for cable sizing? ›
To calculate the Cable Sizing one needs to divide the voltage running through the cable by the target current. For instance, If your wire has a voltage current of 150 Volts and your target is 30 then you divide 150/30. This gives you your target resistance of 5 which is required.
What are the factors for calculating cable size? ›
Determining the correct cable size involves considering factors such as electrical load calculation, voltage and current ratings, conductor material, insulation type, ambient temperature, and installation conditions.
What is cable sizing for dummies? ›
Cable sizing is fairly simple; it is a function of the length of a cable measuring from the power source to the appliance, and the current (amperage) that will flow through it. The longer the cable, or the higher the amperage, the bigger the cable must be to avoid unacceptable voltage losses.
What happens if cable size is too big? ›
What happens if I use the wrong gauge wire? If the wire's amperage capacity is less than the amperage of the load, the wire would eventually overheat and cause a fire. If however, the wire's amperage capacity is higher than the load, nothing would happen.
Can 12 gauge wire handle 30 amps? ›
If you are wiring an outdoor or heavy-duty outlet, you must use a 10-gauge wire with a 30 amp breaker. This is a thicker wire gauge than 12 gauge and can handle higher voltage without the risk of overheating or causing an overload.
How do you calculate wire cable size and current rating? ›
Calculating current rating of cable is easy. Amperage = Current Density * Cross-section Area. Every material has its own Current Density value, for copper it's ~5A/m² (absolute maximum) and for aluminium ~ 3.5A/m²(absolute maximum).
How do you size a cable for a load? ›
To find the cable size, you need to find the load current. Then based on the material you want to use (Copper or aluminium) for the cable, divide the load current by the multiplication factor (4 for Aluminium and 6 for Copper).
What is the formula for calculating copper wire? ›
To calculate this: Take a look at the copper wire size chart and note the diameter ( D ) of the 2/0 wire: 0.3648 in . Apply the following equation: π × (D/2)² × length × metal density = π × (D/2)² × 1 foot × 559 lb/ft³ = 0.406 lb .
The breaker and receptacle must match, so the 50 amp is fine, but the #8 awg is only good for 50 amps and does not comply with 8-104. This is not the case for the stove receptacle or for any other general purpose receptacle that is not continuous load or for a non EV receptacle.
