Nothing uses 60F rated insulation. It doesn't EXIST.
Insulation is also rated in C not in F, and is COMMONLY 80C or 105C depending on the specific type.
I've never seen 60C for any sort of insulation in use in the last 35+ years.
Then there's Teflon, for when you need REAL high temp resistance (but it's expen$ive so it's rarely used outside of high-temp industrial gear or some Mil-Spec stuff).
Insulation is also rated in C not in F, and is COMMONLY 80C or 105C depending on the specific type.
I've never seen 60C for any sort of insulation in use in the last 35+ years.
Then there's Teflon, for when you need REAL high temp resistance (but it's expen$ive so it's rarely used outside of high-temp industrial gear or some Mil-Spec stuff).
I just bought a Trip-Lite 3' SJT power cable with +60C printed right on the jacket. I also just bought 250' of 10/3 from home depot with +60C right on it. I'd say it's very common in residential applications.
I use 90C and 105C in commercial applications.
Might depend on the area and local codes, or the type insulation used - I honestly can't remember seeing "new" 60C rated insulation EVER, just on older wiring that we were ripping out to upgrade or replace.
Power cords I've not paid attention to the temp rating though, since they're not in an enclosed space commonly routed in/through/next to insulation where heat retention is a major issue - 60C rating on THOSE wouldn't be any shock to me.
I would NOT say that 60C insulation is common in residential applications - I'm not sure if it's even LEGAL under the NEC and in those locations that have adopted the NEC as part of their local code requirements (most of the USA) for in-the-wall wiring.
†Allowable ampacities shown are for general use as specified by the National Electrical Code,
2005 Edition, section 310.15 unless the equipment is marked for use at higher
temperatures the conductor ampacity shall be limited to the following:
60°C - When terminated to equipment for circuits rated 100 amperes or less or marked for
size 14 through 1 AWG conductors. MTW wet locations or when exposed to oil or coolant.
75°C - When terminated to equipment for circuits rated over 100 amperes or marked for
conductors larger than size 1 AWG. THWN-2 when exposed to oil or coolant. MTW dry locations.
90°C - THHN dry locations. THWN-2 wet or dry locations. For ampacity derating purposes.
So now you know what is legal in the NEC.
If your wiring is rated as THHN or THWN-2 if wet, then you can use the 90C ampacity chart.
And yes, wiring not THHN rated is available.
