PVC is addressed in a number of sections of the Code, including but not lim-
ited to:
ARTICLE 225 Outside Branch Circuits and Feeders (225.10 Wiring on
Buildings, 230.43 Wiring Methods for 600 Volts, Nominal, or Less.), Table
300.50 Minimum Cover Requirements
ARTICLE 352 Rigid Polyvinyl Chloride Conduit: Type PVC
ARTICLE 355 Reinforced Thermosetting Resin Conduit: Type RTRC
ARTICLE 501 Class I Locations addresses usage of a variety of PVC and
related products
ARTICLE 502 Class II Locations
ARTICLE 503 Class III Locations
When encasing cables in conduit, it is important to consult the National
Electrical Code for sizing issues. If too many wires are run through a particular
conduit, overheating and damage to the wires can occur.
Overcurrent Protection
An overcurrent happens when the electric current exceeds the rating of conduc-
tors or equipment. It can result from overload, short circuit, or ground fault. An
overcurrent device is the component of the electrical system that keeps it from
overloading, short-circuiting, or ground-faulting. It is the job of the overcurrent
device to sense these possible hazards and stop them from happening. The two
types of overcurrent protection are circuit breakers and fuses.
A circuit breaker must be DC rated if it is used in a direct-current circuit due
to the ability of the DC power to continue arcing even after the circuit has been
opened.
Fuses are made of a wire or metal strip that will burn when a maximum
amount of current passes through it, thereby opening the circuit. This action of
the fuse opens the circuit and protects the wire and other system equipment. Fuses
must also be DC rated for the same reasons listed above.
NEC 2011 requires all ungrounded conductors to be
protected by an overcurrent device (240.20). In a PV
system that has multiple sources of power, the overcur-
rent device must protect the conductor from overcurrent
that may come from a source connected to the conductor.
Overcurrent devices are not diodes, charge controllers, or
inverters. Overcurrent protection is not needed when the
PV system is comprised of a single string of modules and
is directly connected to the load without battery storage.
NOTE
Be careful when replacing a fuse
or circuit breaker. If the circuit is open,
you can start a fire or damage the wiring
system if the replacement is done without
a proper inspection or in an unsafe manner.
Arc flash and shock are always a danger if
you are installing the fuse or breaker where
the installation closes the circuit.
CHAPTER 6
System Components 113

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