Just realized I was wrong about using a 12/2 wire for that outdoor receptacle run at my buddy's place in Tempe.

3 comments

3 Comments

the_drew2mo ago

Tempe's heat on a 12/2 wire is a real problem.

viola_reed2mo ago

That's a perfect example of how we build things for the weather we want, not the weather we have. So many systems are pushed right to their limit on paper, with no room for a real world heatwave. It feels like a metaphor for cutting things too close in general, from household budgets to project deadlines. The margin for error just disappears.

joseph5291mo ago

And @viola_reed you're spot on about systems being pushed to the limit. But I gotta push back a little on the 12/2 wire in Tempe heat thing. That's actually a code issue, not just a heat thing. 12/2 copper is rated for 90°C at the insulation level, but you have to derate it for ambient temp. In an attic in Tempe in July that can hit 140°F, a 20 amp circuit on 12/2 is already running right at the ragged edge. The real fix is upsizing to 10 gauge or using THHN in conduit so you get the full 90°C rating instead of the 60°C you're stuck with in Romex. That heatwave margin goes from zero to something real.