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Grounded Electrical Power Distribution System
The National Electrical Code (NEC) requires the use of a "grounded electrical distribu-
tion system". As per this system, one of the two current-carrying conductors is required to
be grounded. This grounded conductor is called the "Neutral / Cold / Return". As this
conductor is bonded to earth ground, it will be at near zero voltage or potential. There is
no risk of electrical shock if this conductor is touched. The other current carrying
conductor is called the "Line / Live / Hot". The connection between the "Neutral" and the
grounding electrode conductor is made only at one point in the system. This is known as
the system ground. This single point connection (bond) is usually made in the service
entrance or the load center. If this connection is inadvertently made in more than one
place, then unwanted currents will flow in the equipment grounding conductors. These
unwanted currents may cause inverters and charge controllers to be unreliable and may
interfere with the operation of ground-fault detectors and over-current devices.
NOTE: A current-carrying conductor that is not bonded to the earth ground cannot
be called a "neutral". This conductor will be at an elevated voltage with respect to
the earth ground and may produce electrical shock when touched.
Polarity and color codes for power cords and plugs for AC devices and appliances
Single phase 120 VAC, 60 Hz AC devices and appliances use 2 pole, 3 wire grounding
configuration for connection to the AC power source. The plug of the power cord has
three pins – two flat pins ( also called poles ) that are connected to the two current-
carrying conductors and a round pin which is connected to a non-current carrying
conductor ( this will carry current only during ground fault conditions ) . One flat pin is
connected to a black current-carrying conductor which is also called "Line/Live/Hot"
pole. The other flat pin is connected to the white current-carrying conductor also called
the "Neutral / Return / Cold" pole. The third round pin is connected to the non-current
carrying green "equipment grounding conductor". This green "equipment grounding
conductor" is bonded to the metal chassis of the device or appliance.
AC output connections
The 120 VAC, 60 Hz version of the inverter uses NEMA 5-15R receptacles for connect-
ing the AC output of the inverter to devices and appliances fitted with a NEMA 5-15P
plug. The two rectangular slots are connected to the current-carrying conductors of the
AC power source inside the inverter. The round slot is the "equipment grounding"
connection and is internally connected to the metal chassis of the inverter.
CAUTION! :
For the 120 VAC, 60 Hz NEMA 5-15R receptacle used in this inverter, the
current carrying conductor connected to the longer rectangular slot is isolated from the metal
chassis of the inverter. Hence, when the metal chassis of the inverter is connected to the
earth ground, the longer rectangular slot is not grounded to the earth ground. The longer
rectangular slot is, therefore, not a "neutral". Do not touch this slot as it will be at an
elevated voltage with respect to the metal chassis / earth ground and may produce an
electrical shock when touched.
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