A variety of factors such as corrosion, physical damage to
receptacles, or inappropriate wiring or installation of electrical outlets can
cause higher than normal electrical resistance when using the Universal Mobile
Connector (“UMC”) NEMA 14-50 adapters to charge Tesla Model S vehicles. When
charging, higher than normal electrical resistance connections to external
energy sources may cause excessive heating of the adapter. In December 2013,
Tesla released an over-the-air software update to address this issue, enabling
the Model S onboard charging system to automatically reduce the charging
current by 25 percent if it detects unexpected fluctuations in the input power
to the vehicle.