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AC Cabling –
AC cabling includes but is not limited to all wires/cables between the AC source
and the inverter, and all the cabling between the inverter and AC outputs (panels, circuit breakers,
and loads). Wiring type and size varies with installation and load. Installation codes will
recommend solid or stranded wires, overall size of conductors, and type/temperature ratings of
insulation around the wire.
Ensure AC breakers and fuses are sized appropriately for current, insulation for voltage, and
ambient temperature ratings. Table 1-1 gives examples of wiring sizes based on the breaker
rating. Examples are based on use with a 2-conductor-plus-ground (3-prong) cable rated at
75°C.
AC Output Neutral Bonding
–
AC input neutral and output neutral must be isolated from
each other. This being noted, the neutral conductor of the inverter AC output circuit (i.e. AC
output neutral) is automatically connected to the safety ground during inverter operation. When
using an AC utility power source and the inverter is in charging mode, this connection is not
present.
DC Cabling –
DC cabling includes but is not limited to all cables and connectors between the
batteries, the DC disconnect and breakers/fuses, and the inverter. Heavy truck or RV
installations normally require multi-strand, insulated cables for flexibility and durability; they also
usually require over-current protection devices. DC cables must be copper and must be rated to
at least 75°C. The cables should also terminate with lugs that fit the DC stud terminals on the
inverter (m8 x 1.25). Choosing small cables may result in variable device functionality.
DC Disconnects and Over-Current Devices –
The DC system from the inverter to the
battery must be equipped with an over-current device and disconnect. Typically this consists of a
circuit breaker, a “fused-disconnect,” or a separate fuse with a DC disconnect. Do not confuse
AC circuit breakers with DC circuit breakers as they are not interchangeable. The rating size of
the cables must match rating of fuses or breaker selected. Breaker or fuse and disconnect
should be situated as close as possible to the battery, on the positive cable.
Batteries –
The inverter sources input power from a 12VDC deep cycle battery or group of
batteries. The inverter converts the 12VDC input power to 115VAC output.
Ground Fault Circuit Interrupters (GFCIs) –
In the case where the current to ground
exceeds specified value, but is less than the rating to blow the circuit breaker, a GFCI device will
de-energize the circuit. This protects from electric shock and is usually required for wet/damp
locations.
