And also (and esp. if using outdoors) make sure you keep the connections clean and free of corrosion. A poor connection may "seem" to be working, but electrically can have a much higher resistance to current than a normal "clean" connection. Resistance can lead to heat, and heat can lead to fire or, at best, melted equipment.
In the middle or end of a charge, always (or at least regularly) check all of your connections (both at the wall socket and your "extension" to the EVSE) for excessive heat, look for melting, and any abnormalities on the metal contacts. Checking in the middle of a charge is important. Checking very much longer after a charge has completed could miss certain heating issues as things may have cooled by then (the car having stopped drawing current at the maximum level).
Case in point: Somebody here recently reported that they'd noticed that their EVSE cord (just the normal one, not using an extension) had melted at the wall socket in their garage. Probably nothing was wrong with the EVSE -- just the contacts in the wall socket in his garage were old, dirty, and/or corroded (or the wiring to the socket is somehow compromised). Due to the poor connection, all his recent "full load" EV charging had likely generated excessive heat and started to melt the nearby plastics. If he had regularly checked for heat while charging, he might have noticed the problem. He is lucky he didn't start a house fire.
