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NEC article 625 and Electric Vehicles
The NEC, National Electric Code, is part of the National Fire Code and is mandated by most state or local law in the USA. The code covers all wiring in and around structures.
The NEC article 625 covers the wires and equipment used to supply electricity for charging an electric vehicle. The 2008 version does not cover motorcycles, industrial trucks, or golf carts. It covers the charging process to the end of the connector that plugs into the vehicle. It does not cover whatever happens with that power once it enters the vehicle.
1999 was the first edition of NFPA 70 the National Electric Code (published by the National Fire Protection Association) to include article 625 about Electric Vehicle Charging. Coincidently, this is the first edition after the introduction of the GM EV1 vehicles. Minor changes have been made over the years. The following notes are based on the 2008 edition.
If the charging power source is 120 volts and is powered by a 15 or 20 amp standard ground fault protected outlet NEC article 625 has no other requirements... The 120 Volt power and lower power is safer and allows emergency charging anyplace. The switch for the outlet is an extra level of safety. The switch for the outlet is turned off when not in use, before the extension cord is connected to the vehicle and before the extension cord is disconnected from the vehicle. It improves safety in a potentially wet environment.
If the voltage or current exceeds 120 volts or 20 amps, the other requirements of NEC article 625 apply.
There are requirements for the connector:
It must be polarized
It cannot be interchanged with any standard connector
It must be touch safe when in use and not in use.
It must have a latch to prevent unintentional disconnection
It must have a grounding connection that makes first and brakes last
All of these requirements are covered by using a SAE J1772 compliant connector and communications (click for information page)
The charging equipment must be:
Marked with the intended use (electric vehicle charging) and if the location has ventilation required for some battery types.
The cable used between the equipment and vehicle can only be one of several types specifically designed for EV charging, all types have the first two letters in the wire type as EV.
There will be an interlock that only supplies power to an electric vehicle.
Power will automatically disconnect if the cable is disconnected.
Power will automatically disconnect if the cable pulled on (tension) before it separates or fails.
There will be over current protection
Ground fault protection is required
There are requirements about storing the cable between used 18-48 inches above the floor
There are other requirements for very high power charging systems and interactive system beyond the scope of these notes.
For indoor sites, there are requirements for batteries that could produce flammable gasses (flooded lead acid) and require ventilation that is beyond the scope of these notes
Outdoor charging is permitted.
I have provided this as an introduction to article 625. You need to consult an actual copy of the current NEC and determine what is correct for your application. Contacting a professional electrical engineer or and electrical contractor may help but for most people this is all very new. Your local building department may also be able to help.
Minor changes are going to appear in the 2011 edition of the NEC, National Electric Code which will be published in November. The main change is said to include motorcycles and plug-in hybrids which were not previously covered.
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SAE J1772:2010(tm) is a trademarked standard of the Society of Automotive Engineers.