30 Amp Plug
50 Amp Plug
120 Volt Electrical System
Provides general information about the components and functions of the 120 Volt Electrical System (AC) in Newmar
coaches.
Power Sources
There are three types of alternating current (AC) power sources available to the coach: shore power,
generator power,
and inverter power. Shore power
is provided by the RV park or by home service outlets and should be used whenever
possible.
Generator power
should
mainly be
used when shore power is not available, specifically while
traveling, when
120
Volt
power is necessary to
run high amperage loads, or when
dry camping requires
120 Volt
for
battery charging.
Inverted power
is mainly used for light 120 Volt
loads when shore power is not available and generator
power is not
desired.
Generator Power
Generator power is produced within the generator and is output through the main wiring to the transfer switch.
From the
transfer switch, the power moves to the main breaker box where it is dispersed to individual circuits (outlets) and hard-
wired components such as a water heater or boiler.
From
the inverted circuits, generator power will then travel through
the inverter’s internal transfer switch and back to the inverted subpanel to be dispersed through the individual breakers
to
the outlets or appliances.
Inverter Power
This type of power starts at the battery bank.
The battery bank
supplies 12 Volt power through cables
to the inverter,
which uses the 12 Volt
direct current
to produce 120 Volt
alternating current.
The inverter performs this action by using
a
transformer to increase the voltage and modify the higher voltage into a useable alternating current power. Power then
goes to the inverted sub panel, which is dispersed through the individual breakers to the outlets or appliances.
The inverter may
provide
battery charging while 120 Volts is supplied via the generator or shore power.
The inverter
performs this action
by using the transformer to decrease
the voltage and rectify
the alternating current into useable
direct
current voltage.
This is
regulated by internal sensing circuitry based upon the battery bank’s state of charge and
several
other factors, depending on the coach's particular inverter brand and type.
Shore Power
Most RV parks provide 30 Amp,
120 Volt
at
the site; however, many parks also
provide
50 Amp,
240 Volt
service to
accommodate
the electrical needs of newer
and larger coaches.
Shore power is supplied
to the coach via a power cord.
Two sizes of
power cords are found in Newmar
coaches:
50 Amp and 30 Amp.
The 50 Amp cords are
made up of four
conductors #8 stranded wire
and a molded plug.
The 30 Amp
cords are
made up of three
conductors #10 stranded
wire and a molded plug.
Shore power enters through the 30 or 50
Amp
power cord to the
power cord reel (if
equipped)
.
From the power cord reel, it
travels
to the transfer switch and then to the
main breaker box where it is dispersed
to the
individual circuits to supply power to
hard-
wired components such as
air conditioners,
w
ater heaters, etc. and then
to the inverter (if
equipped).
The inverted circuits move from the inverter's
internal transfer switch to the inverter subpanel (a smaller breaker box).
From the subpanel, the power circulates to the
individual breakers and to the electrical outlets and appliances.
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