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Grounded Electrical Power Distribution System
The
N
ational
E
lectrical
C
ode (NEC) requires the use of a “grounded electrical distribution
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 - PSE-24125 A / PSE-24175A
The 120 VAC, 60 Hz version of these inverters use 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 receptacles in PSE-24125A and PSE-
24175A, 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
.
AC output connections - PSE-24275A
The AC output connections of inverter model PSE-24275A have three insulated conduc-
tors – one black and one white for carrying current and one green for “equipment
grounding”. The green color “equipment grounding” conductor is connected to the metal
chassis of the inverter. These three conductors exit through a pocket in the front side of the
inverter. These three conductors are used for hard-wiring the inverter to a breaker panel.
For drawing the full rated power of the inverter, the output conductors should be
hard wired to a suitable breaker panel.
