Heavy Duty Extension Cord for EV Charging Use with 10-30P male plug and 14-50R female receptacle: This heavy-duty EV cord adapter is perfect for your need. With a durable 10-gauge copper construction, this 10-30 to 14-50 adapter delivers reliable power for EV charging. 1.5 Ft Heavy Duty Extension Cord for EV Charging. The EV extension cord has a female connector end that features 50 Amp 14-50R 125/250 Volt compatible with the leading EV manufactures vehicles.