THWN-2 Wire Ampacity

[Andy Compton]

I'm installing a subpanel in my detached garage and noticed my wire is 6 gauge THWN-2. When I looked up the ampacity chart I see that it has a different rating than regular THWN and was wondering if I can really go past 60 amps for the subpanel. Thoughts?

Here's the chart: http://www.cerrowire.com/ampacity-charts

Thanks!

[Scott T Smith]

Yes, it is rated for more current since the insulation is 90c rated.

[John McClanahan]

While the insulation will a larger amp draw, it is resistance in the wire that causes it to warm up. That resistance can lead to a voltage drop. So, if you are running say, 40-50 amps total draw and turn on a larger tool, it may have an extended startup time.

John

[Andy Compton]

Got ya. 60 amps should be great for the shop so I'll stick with it. Thanks for the info!

[Rollie Meyers]

6 AWG THWN is rated for 65A, if the calculated load is under 65A, a 70A breaker could be used as there are no 65A fuses or circuit breakers & it falls under the rules allowing the next larger size overcurrent device.