This ampacity chart shows the allowable ampacity for copper conductors with temperature ratings of 60°C, 75°C, and 90°C.
|18||not specified||not specified||14|
|16||not specified||not specified||18|
*Listed values are allowable ampacities of insulated conductors rated up to and including 200 volts, no more than 3 current-carrying conductors in a raceway, based on ambient temperature of 30 degrees C (87 degrees F).
**We recommend that ampacity values be derated to 80% of listed values for continuous loads.
***Values are from the National Electric Code 2014 Edition, Table 310.15. Also see Section 240.4(D).
What is ampacity?
Ampacity is the maximum amount of current that a conductor can carry without degrading.
What does this mean for your solar installation?
Use the ampacity chart above to make sure that you are not running more amps through a wire than it can carry safely. If you find that the number of amps running through your wire exceeds the number on the chart, you may want to consider switching to a thicker wire.
What will happen if the number of amps running through a wire exceeds its ampacity?
The wire may deteriorate and cause an electrical fire.
What other factors affect ampacity?
Ambient temperature and the number of other current-carrying wires that are bundled together may derate a wire’s ampacity. What does mean for your installation? Let’s say you plan to run 6 wires in the same raceway. If you planned on using AWG 8 for all of those wires, you may want to consider using something thicker, like AWG 6.
According to the NEC 2014, 4-6 conductors in a single raceway should have their listed ampacities derated to 80%; 7-9 conductors derated to 70%; 10-20 conductors derated to 50%.