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Wire Size Ampacity Chart


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Thers a ton of them out there, when I practiced I just used the NEC but had plenty of other shorter basic references such as Uglys.

HOWEVER what most non electricians or non engineers may not realize THE AMPACITY DEPENDS ON MANY FACTORS   OTHER THEN THE WIRE SIZE ALONE.    It has to do with how much current can be carried WITHOUT DEGRADING OR HARMING OR MELTING THE INSULATION  IE how  well heat can be dissipated from the conductors to the surroundings

 For example a conductor in free air has a much higher ampacity then one enclosed or jacketed and if enclosed how many conductors in what size raceway plus the type and class of Insulation etc etc etc on and on lol its worse then reading a law book. Regardless, when it comes to sizing low voltage DC conductors in high current applications such as for inverters or chargers, bigger is better to reduce line voltage drop which is a function of Current,,,,,,,Wire Size,,,,,,,,Distance  

 Best wishes yall

John T

 

 

 

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Just one more thing to consider.  Many of us use welding wire which has very high temperature ratings but most terminals unless marked are not rated for high temperatures.  To account for this the wire capacity needs to be derated for the terminal temperature rating.  Fuses for instance do not play well with high temperatures. Blue Sea has an app that helps to size wire for fuses and other conditions.

Edited by Randyretired
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On 4/30/2022 at 3:52 PM, Randyretired said:

Just one more thing to consider.  Many of us use welding wire which has very high temperature ratings but most terminals unless marked are not rated for high temperatures.  To account for this the wire capacity needs to be derated for the terminal temperature rating.  Fuses for instance do not play well with high temperatures. Blue Sea has an app that helps to size wire for fuses and other conditions.

My tig rig that i weld with uses #4 cable. I run at 250-290 amps with it for hours, gets warm but that's all. 

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25 minutes ago, GlennWest said:

My tig rig that i weld with uses #4 cable. I run at 250-290 amps with it for hours, gets warm but that's all. 

 As I discussed above, a single conductor IN FREE AIR has a higher ampacity versus if enclosed. Again it has to do with the ability to dissipate heat without degrading the insulation....

John T 

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