Equipment Grounding
Equipment grounding conductors should be a bare wire or a green wire. [NEC
690.41] They need to handle the highest current that could flow through the cir-
cuit. [NEC 690.41–690.44]
PV Module Grounding
Article 690.5 discusses grounding and fault protection:
Use a single ground point.
Ground one conductor (> 50 V).
Ground the neutral wire of a three-wire system.
Safety Hints for Testing a PV System
Before testing any PV system, know the answers to the following questions:
What are the system voltages?
What are the system currents?
How many circuits are there?
What are the overcurrent devices?
Where are the overcurrent devices?
Where is the system disconnected?
Where is the safety equipment located?
After those questions are answered, then it is time to go to the PV system site.
When at the PV system site, always take these precautionary measures:
1. Take off any jewelry.
2. Walk around the system and document any dangerous circumstances—write
them down and take pictures.
3. Locate the inverter and battery.
CODE
NEC 2011, 200.6 (6)
A single-conductor, sunlight-resistant, outdoor-rated cable used as a grounded conductor in
photovoltaic power systems, as permitted by 690.31, shall be identified at the time of installation
by distinctive white marking at all terminations.
Reprinted with permission from NFPA 70
®
, National Electrical Code
®
, Copyright© 2010, National Fire
Protection Association, Quincy, MA.
CHAPTER 2 Essential Safety Practices for Designing and Installing PV Systems 41
4. Check system grounding.
5. Inspect all the system disconnect switches.
6. Check all the fuses.
7. Sever the source circuit, tag, and lockout if working on the PV system.
8. Calculate the open-circuit voltage for each string.
9. Measure the voltage from each connector to the ground.
10. Gauge the voltage from line to line.
Once the circuits are tested, the PV system testing can begin. Remember: Do
not test the PV system alone, and always take these steps:
1. Keep hands dry.
2. Put on insulating gloves.
3. Use only one hand if possible.
4. Have someone at the disconnect switch.
5. Keep work area clear.
6. Measure wire voltage before disconnecting it.
7. Tape the end of any disconnected wire.
8. Reconnect source circuit wires before disconnecting another.
42 ADVANCED PHOTOVOLTAIC INSTALLATIONS
Chapter 2 Summary
This chapter focuses on safety practices when installing, connecting, and
operating PV power systems. The tips and recommendations encourage working
safely with PV systems. Specific safety components aid the steps of installing PV
systems. Marking and labeling requirements help identify live electrical circuits
and locate different parts of the PV system. Safety hints ensure that PV system
testing and operating are smooth.
Key ConCeptS and termS
Converter
Labeling
Lead-acid battery
Marking
Module
National Electrical Code (NEC)
Non-habitable building
Occupational Safety and Health
Administration (OSHA)
Overcurrent protection
Personal protective equipment (PPE)
Volt (V)
Chapter 2 aSSeSSment
Essential Safety Practices for Designing and Installing PV
Systems
1. A stairway or ladder is required for every 19-inch elevation break on a job site,
as required by OSHA.
A. True
B. False
2. What mA electrical current can paralyze muscles and cause falls on a jobsite?
A. 10
B. 30
C. 50
D. 75
3. What are lockout and tagging used for?
A. Removing hazards prior to energizing equipment
B. Preventing people from energizing electrical circuits while they are being
serviced
CHAPTER 2 Essential Safety Practices for Designing and Installing PV Systems 43
C. Disabling a PV system from being interconnected to the utility grid until
inspections have been passed
D. Identifying and isolating defective components in an electrical system
until service can be performed
4. What is the purpose of ground-fault protection devices?
A. They interrupt the circuit below the fuses or breaker-disconnect
amperage, before electric shock can drive the heart into ventricular
fibrillation.
B. They reduce the probability of electrical shock to service personnel.
C. They limit losses of the PV-output energy to ground.
D. They reduce ruin of structural supports from rapid electrolysis.
5. What should not be done if the electrolyte freezes?
A. Discharge the battery.
B. Charge the battery.
C. Heat with a hair dryer.
D. Remove the battery.
6. What color are equipment-grounding conductors?
A. White
B. Black
C. Green
D. Orange
7. OSHA requires fall protection where an employee or worker can fall how
many feet?
A. 4
B. 6
C. 8
D. 10
8. Which of the following devices does the NEC require to be a part of PV systems
mounted on residential dwellings?
A. Utility interconnection
B. Stand-off mount for the PV modules
C. Accessible source-circuit combiner box
D. Ground-fault device
9. The purpose of an inverter is to convert:
A. AC at one voltage to DC at the same voltage.
B. DC voltage to AC voltage.
C. AC at one voltage to AC at the same or another voltage.
D. DC at one voltage to DC at another voltage.
44 ADVANCED PHOTOVOLTAIC INSTALLATIONS
10. What is the best method to avoid electrical shock while troubleshooting a PV
system?
A. Wear protective gear, turn off switches, and measure voltages and
currents.
B. Inspect all questionable terminals, wear rubber gloves, and turn off all
switches.
C. Keep one hand behind your back, with all switches turned off, and touch
only grounded surfaces.
D. Wear shoes with soft rubber soles, turn off all switches, and don’t touch
metal surfaces.
CHAPTER 2 Essential Safety Practices for Designing and Installing PV Systems 45
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