In lay terms, this means that all metal equipment must be grounded.
Ungrounded metal equipment can cause ground fault shock. There are dangers to
ground fault shock. A person who touches a piece of “live” equipment will be
shocked and possibly electrocuted.
Following proper safety procedures will eliminate this.
Equipment grounding wires only carry current when a ground fault occurs.
This protection is provided by having the grounding wire connect to all metal equip-
ment parts. The wire connects to those parts that do not normally carry current.
The grounding wire should not be switched, fused, or interrupted. It con-
nects all metal receptacles, such as electrical boxes, device
frames, chassis, and panel mounting.
Separate grounding is often unnecessary when metal
conduit or armored cables are used because they can often
double as the equipment grounding conductor. Grounding
conductors connecting frames to the conduit are still
necessary.
AC Grounding
During installation and after completion, it is important to be able to see that the
grounding is properly terminated. You should be able to clearly track it through
the whole system. Continuity of the grounding is important.
TECH TIPS
Equipment grounding conductors
should be able to handle 125 percent of
the PV system’s short-circuit currents.
CODE
685.12 Direct-Current System Grounding. Two-wire DC circuits shall be permitted to be
ungrounded.
690.17 Switch or Circuit Breaker. The disconnecting means for ungrounded conductors shall
consist of manually operable switches or circuit breakers complying with all of the following
requirements:
1. Located where readily accessible
2. Externally operable without exposing the operator to contact with live parts
3. Plainly indicating whether in the open or closed position
4. Having an interrupting rating sufficient for the nominal circuit voltage and the current
that is available at the line terminals of the equipment
Reprinted with permission from NFPA 70®, National Electrical Code®, Copyright
©
2010, National Fire
Protection Association, Quincy, MA.
194 ADVANCED PHOTOVOLTAIC INSTALLATIONS
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