4 Gauge 4 AWG 25 Feet Red + 25 Feet Black ( 50 Feet Total ) Welding Battery Pure Copper Flexible Cable Wire -- Car, Inverter, RV, Solar by WindyNation

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This allows for a 3% voltage drop through the cable, which is acceptable for most automotive wiring jobs (3% of 12 volts = 0.36 volts). It’s a good guide. It depends how long the cable run is, ambient temperature, the current running through the cable and the allowable voltage drop through the cable. The higher the number, the smaller the wire size. For example 20 AWG cable is much smaller than 10 AWG. Now you have a cross-sectional area. So, use the Cable Size Chart to figure out what size cable it is. Buy cable with an AWG size. This is an American Standard for cable sizes and you’ll likely get the correct cabling for the job.

AWG (American Wire Gauge) to mm (Millimeters squared) Conversion AWG (American Wire Gauge) to mm (Millimeters squared) Conversion

Let’s stay with this example and see what maximum current the 14 AWG cable can handle over a 20 metre cable run. We’ll use the same values we started with above, then reduce the current until the cable cross-sectional area is below 2.1 sq. mm (or 14 AWG). Say you run a positive cable from the battery to a compressor. Distance is 2 metres. If you run the negative to ground from the compressor at the compressor, then total cable length is 2 metres (plus a bit for the negative cable). The point is, the only information that’s useful is the cross-sectional area of the cable. Everything else is misleading rubbish. Use the calculator below to figure out the cross-sectional area of the cable, then use the Cable Size Chart to match it to the nearest size.Say you have a terminal box and want to size the supply cable. Off the terminal box you have a compressor with a maximum current draw of 40 Amps and a fridge with maximum current draw of 10 Amps. Auto cable like the SCA example above also uses the 5mm cable terminology. But auto cable is referring to the overall diameter, insulation included , not the cross-sectional area.

AWG (American Wire Gauge) Size Conversion Calculator Wire AWG (American Wire Gauge) Size Conversion Calculator

Hi Ross. Thanks, I’m glad it is helpful. The calculators can only be used when you have Internet reception. However, I’ll do another version in the Free Resources section that will use Microsoft Excel. This way, you’ll be able to use it anywhere. Stay tuned! Cheers, Andrew Reply You’ll see in the image above, it says “Size: 5mm (2.90mm 2)”. the 5mm refers to the diameter of the cable plus the insulation.B&S stand for Brown & Sharp Wire Gauge… not Battery & Starter as some automotive wiring suppliers seem to imagine! Only if the cable has been sized correctly in the first place. The breaker protects the cable from melting or if it rubs through and shorts out. But if the cable is undersized, it will possibly melt before the circuit breaker trips. It totally depends on the application. Use our Cable Size Calculator to find out exactly what you need. Do not rely on suppliers’ specification, as they are generally misleading or completely incorrect.

AWG) Cable / Conductor Sizes American Wire Gauge (AWG) Cable / Conductor Sizes

gives a cable cross-sectional area of 1.53 sq. mm. This corresponds to a 14 AWG cable in the Cable Size Chart above. Voltage drop gets converted to heat in the cable. The lower the voltage drop, the less heat generated. You’ll notice under the Voltage Drop box it says, “Max. 0.36V for 6 AWG & 16 ISO cables and smaller. Max. 0.24V for 4 AWG & 25 ISO cables and larger.”.Most suppliers of auto cable don’t though. So you have no idea of what the cross-sectional area is. If measuring a single strand is too difficult, measure the diameter of the whole bundle. It’s not as accurate but will give you an indication at least. Just make sure you go down a cable size if you do this. You might think I’m being unfair. Okay, let’s increase our cable run by just one metre, to 3 metres. What happens? The required cross-sectional area jumps to 2.30 sq. mm, which means you have to use the next size up… 12 AWG. Apologies in advance for any repetition. However, many of these questions are asked in slightly different ways.