Cool has for generations of young and old alike pretty much means basically the same thing. From the Fonz to Ferris Bueller cool means popular, awesome, groovy, wicked or fly. When something ain't too cool, it's not okay.
With the temperatures in the 90s lately here in Connecticut, cool also means staying cool and that means air conditioning. Central air is popular here, all though not in use for more that three to four months a year, many house's have a system.
Part of my routine for checking the outdoor compressor is to look at the units data plate and open the service switch next to the unit. In the summer opening the box first without knocking can have me running. The reason for looking inside the service switch is to check the wiring. Most often, all though simple, the wiring is done by the installer, not an electrician.
Sometimes mistakes are made.
Opening a service switch recently, it was deja vu all over again. What I saw was a very toasted neutral (white) wire. The reason a wire gets a nice tan or worse cooked, is from too much resistance. To prevent a wire from have too much amperage potentially flowing through it, the wire must be appropriately sized for the job. In addition the wire must be protected by a matching sized circuit breaker. So a 20 amp wire must be protected by a 20 amp breaker.
With A/C compressors things get a bit counter intuitive. That is why there is the manufactures data plate. It's not a great read, but it has all the necessary and important information on how to properly wire the unit. With A/C compressors the wire is always smaller than the breaker. This is because when the unit starts there is a temporary surge of electricity. The engineers who design these things know this and put a minimum wire ampacity on the data plate. The thing about engineers is if nothing else they are very precise.
This unit had a minimum wire ampacity of 31.9. Everyone knows you round down if the number is under five.
Except with electricity. Less is never a good practice.
The fried wire attached to the terminal was rated at 30 amps.
And that ain't too cool.