Transcript PV Systems and Safety

Photovoltaic (PV) Systems and Safety
Workshop on Installing Photovoltaic Systems
Florida Solar Energy Center
Cocoa, Florida
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Key Elements of a PV
System
energy
source
load
utilization
power
conditioning
PV Array
Inverter
Charge
Controller
load
center
energy
distribution
energy
conversion
energy
storage
battery
electric
utility
network
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General Program Standards for
PV Installation Practitioners
Given a grid-connected PV system design, including major
components, drawings and instructions, the PV practitioner will
install a grid-connected PV system that meets the needs of the
customer, the site, and local code requirements by:
1. Working safely with photovoltaic systems
2. Conducting a site assessment
3. Selecting a system design
4. Adapting the mechanical design to the site
5. Adapting the electrical design to the site
6. Installing subsystems and components at the site
7. Performing a system checkout and inspection
8. Maintaining and troubleshooting the system
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PV Systems and Safety
PV installer safety:
Safe work area
Safe use of tools and
equipment
Safe practices for
personnel protection
Awareness of safety
hazards and how to
avoid them
A safe PV system:
PV system codes and
standards
Public safety codes
and standards
Identification of safety
hazards
Identification of
environmental hazards
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The Need for Safe Work
Practices and Standards
Each year...
Nearly 6,000 workplace fatalities
50,000 deaths from workplace-related
illnesses
5.7 million non-fatal workplace injuries
Injuries alone cost U.S. businesses
over $125 billion.
Source: OSHA Publication 2056
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OSHA Safety Categories
Personal Protection Equipment (PPE)
Electrical
Falls
Stairways and Ladders
Scaffolding
Power Tools
Materials Handling
Excavation
Cranes
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NEC Article 690: Solar
Photovoltaic Systems
I. General
II. Circuit Requirements
III. Disconnecting Means
IV. Wiring Methods
V. Grounding
VI. Marking
VII. Connection to Other Sources
VIII.Storage Batteries
IX. Systems Over 600 Volts
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PV Systems and the
National Electrical Code®
In addition to Art. 690, other NEC articles may also apply to PV installations:
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Article 110:
Article 210:
Article 230:
Article 240:
Article 250:
Article 300:
Article 310:
Article 400:
Article 480:
Article 490:
Article 685:
Article 705:
Article 720:
Requirements for Electrical Installations
Branch Circuits
Disconnect Means
Overcurrent Protection
Grounding
Wiring Methods
Conductors for General Wiring
Flexible Cords and Cables
Storage Batteries
Equipment, over 600 Volts, Nominal
Integrated Electrical Systems
Interconnected Electric Power Production Sources
Circuits and Equipment Operating at Less than 50 Volts
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NEC Article 690: Summary
Section
Contents
NEC Cross
References
I
General: Scope, Definitions, Installation, Ground-fault protection, AC modules
Article 240
II
Circuit Requirements: Maximum voltage, Circuit sizing and current, Overcurrent
protection, Stand-alone systems
III
Disconnecting Means: Conductors, Additional provisions, PV equipment,
Fuses, Switches and circuit breakers, Installation and service
IV
Wiring Methods: Methods permitted, Component interconnections, Connectors,
Access to boxes
V
Grounding: System grounding, Point of system grounding connection,
Equipment grounding, Size of equipment grounding conductor, Grounding
electrode system
VI
Marking: Modules, AC modules, PV power source, Point of common connection
VII
Connection to Other Sources: Identified interactive equipment, Loss of
interactive system power, Ampacity of neutral conductor, Unbalanced
interconnections, Point of connection
Article 230
VIII
Storage Batteries: Installation, Charge control, Battery interconnections
Articles 400,
480
IX
Systems over 600 Volts: General, Definitions
Articles 110,
210, 240
Article 230
Articles 310,
400
Article 250
Article 490
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Personal Protective
Equipment (PPE)
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Personal Protection
Equipment Responsibilities
Employer
Assess workplace for hazards.
Provide personal protective equipment (PPE).
Determine when to use.
Provide PPE training for employees and
instruction in proper use.
Employee
Use PPE in accordance with training received and
other instructions.
Inspect daily and maintain in a clean and reliable
condition.
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Examples of PPE
Body Part
Protection Equipment
Eye
Safety Glasses, Goggles
Face
Face Shields
Head
Hard Hats
Feet
Safety Shoes
Hands and arms
Gloves
Bodies
Vests
Hearing
Earplugs, Earmuffs
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Eye Protection
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Eye Protection for Employees
Who Wear Eyeglasses
Ordinary glasses do not provide the required
protection. Proper choices include:
 Prescription glasses with side shields and
protective lenses
 Goggles that fit comfortably over corrective
glasses without disturbing the glasses
 Goggles that incorporate corrective lenses
mounted behind protective lenses
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Preventing Electrical
Hazards: PPE
 Proper foot
protection (not
tennis shoes)
 Rubber insulating
gloves, hoods,
sleeves, matting,
and blankets
 Hard hat (insulated nonconductive)
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Safety Shoes
Impact-resistant toes and heatresistant soles protect against
hot surfaces common in
roofing and paving
Some have metal insoles to
protect against puncture
wounds
May be electrically conductive
for use in explosive
atmospheres, or
nonconductive to protect from
workplace electrical hazards
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Selecting the Right Hard
Hat
Class A
 General service (building construction, shipbuilding,
lumbering)
 Good impact protection but limited voltage protection
Class B
 Electrical/utility work
 Protects against falling objects and high-voltage
shock and burns
Class C
 Designed for comfort, offers limited protection
 Protects against bumps from fixed objects, but does not
protect against falling objects or electrical shock
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Hand Protection
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Electrical Safety
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Facts about Electrical
Hazards
About 5 workers are
electrocuted every week.
Causes 12% of young
worker workplace
deaths.
Takes very little
electricity to cause harm.
Significant risk of
causing fires.
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Electrical Injuries
There are four main types of electrical
injuries:
 Electrocution or death due to
electrical shock
 Electrical shock
 Burns
 Falls (caused by shock)
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Shock Severity
Severity of the shock depends
on:
 Path of current through the
body
 Amount of current flowing
through the body (amps)
 Duration of the shocking
current through the body
LOW VOLTAGE DOES NOT
MEAN LOW HAZARD
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Dangers of Electrical
Shock
Currents above 10 mA* can
paralyze or “freeze” muscles.
Currents more than 75 mA can
cause a rapid, ineffective
heartbeat -- death will occur in a
few minutes unless a defibrillator
is used.
75 mA is not much current – a
small power drill uses 30 times
as much.
Defibrillator in use
* mA = milliampere = 1/1,000 of an ampere
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Burns
Most common shockrelated injury
Occurs when you touch
electrical wiring or
equipment that is
improperly used or
maintained
Typically occurs on hands
Very serious injury that
needs immediate attention
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Falls from Electrical Shock
Electric shock can also
cause indirect injuries.
Workers in elevated
locations who
experience a shock
may fall, resulting in
serious injury or death.
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Falls in Construction
Falls are the leading cause of deaths in the
construction industry.
Most fatalities occur when employees fall from
open-sided floors and through floor openings.
Falls from as little as 4 to 6 feet can cause
serious lost-time accidents and sometimes death.
Open-sided floors and platforms 6 feet or more in
height must be guarded.
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Fall Protection Options
Personal Fall
Arrest System
(PFAS)
Guardrails
Safety Net
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Personal Fall Arrest
Systems
You must be trained how to properly use PFAS.
PFAS = anchorage, lifeline and body harness.
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Safety Line
Anchorages
Must be independent of
any platform anchorage
and capable of
supporting at least 5,000
pounds per worker.
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Safety Nets
Place as close as possible, but no more than 30 feet
below where employees work.
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Roofs
If you work on roofs and can fall
more than 6 feet, you must be protected.
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Ladder Angle
Non-self-supporting
ladders (that lean
against a wall or other
support):
Position at an angle
where the horizontal
distance from the top
support to the foot of
the ladder is 1/4 the
working length of the
ladder.
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Ladder Rail Extension
When using a
portable ladder for
access to an upper
landing surface, the
side rails must extend
at least 3 feet above
the upper landing
surface.
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Near Energized Electrical
Equipment
If using ladders where
the employee or the
ladder could contact
exposed energized
electrical equipment,
they must have
nonconductive siderails
such as wood or
fiberglass.
This is an unsafe condition
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Overhead Power Lines
Stay at least 10 feet
away.
Post warning signs.
Assume that lines are
energized.
Use wood or fiberglass
ladders, not metal.
Power line workers
need special training
and PPE.
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Fall Protection Training
Workers should be trained in the following areas
(as applicable):
The nature of fall hazards in the work area.
The correct procedures for erecting,
maintaining, and disassembling the fall
protection systems to be used.
The proper use, placement, care and handling of
ladders.
The maximum intended load-carrying capacities of
ladders.
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Power Tools
Must be fitted with guards
and safety switches
Extremely hazardous when
used improperly
Different types determined
by their use:
 Electric
 Pneumatic
 Liquid fuel
 Hydraulic
 Powder-actuated
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Switches
Hand-held power tools must be
equipped with one of the following:
Constant pressure switch
Shuts off power upon release
Examples: circular saw, chain saw,
grinder, hand-held power drill
On-Off Switch
Examples: routers, planers, laminate
trimmers, shears, jig saws, nibblers,
scroll saws
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Power Tool Precautions
 Disconnect tools when not in use, before servicing and
cleaning, and when changing accessories.
 Keep people not involved with the work away from the
work.
 Secure work with clamps or a vise, freeing both hands to
operate the tool.
 Don’t hold the switch button while carrying a plugged-in
tool.
 Keep tools sharp and clean.
 Consider what you wear – loose clothing and jewelry can
get caught in moving parts.
 Remove damaged electric tools & tag them: “Do Not
Use.”
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Power Tool Precautions
 Don’t carry portable tools
by the cord.
 Don’t use electric cords
to hoist or lower tools.
 Don’t yank cord or hose
to disconnect it.
 Keep cords and hoses
away from heat, oil, and
sharp edges.
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Electric Power Tools
To protect a worker from shock, these tools must:
 have a 3-wire cord plugged into a grounded receptacle
 be double insulated, or
 be powered by a low-voltage isolation transformer
Double
insulated
markings
Plug with a
grounding
pin
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Hazard: Inadequate
Wiring
Hazard: Wire too small for the
current.
Example: Portable tool with an
extension cord that has a wire too
small for the tool
 The tool will draw more current
than the cord can handle,
causing overheating and a
possible fire without tripping the
circuit breaker.
 The circuit breaker could be the
right size for the circuit but not
for the smaller-wire extension
cord.
Wire Gauge
WIRE
Wire gauge measures
wires ranging in size
from number 36 to 0
American wire gauge
(AWG)
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Grounding
Grounding creates a lowresistance path from a
tool to the earth to
disperse unwanted
current.
When a short or lightning
occurs, energy flows to
the ground, protecting
you from electrical shock,
injury and death.
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Hazard: Improper
Grounding
Tools plugged into
improperly grounded
circuits may become
energized.
Broken wire or plug on
extension cord
Some of the most
frequently violated OSHA
standards
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Electric Tools: Good
Practices
 Operate within design limits.
 Use gloves and safety
shoes.
 Store in a dry place.
 Don’t use in wet locations
unless so approved.
 Keep work areas well lit.
 Ensure cords don’t present
a tripping hazard.
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Power Tool Summary
Hazards are usually the result of improper
tool use or not following one or more of the
proper protection techniques:
 Inspecting the tool before use
 Using PPE (Personal Protective Equipment)
 Using guards
 Properly storing the tool
 Using safe handling techniques
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Lockout and Tagging of
Circuits
Apply locks to power source
after de-energizing.
Tag deactivated controls.
Tag de-energized equipment
and circuits at all points where
they can be energized.
Tags must identify equipment or
circuits being worked on.
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Electrical Equipment Training
Train employees working with electric
equipment in safe work practices, including:
De-energizing electric equipment before
inspecting or repairing
Using cords, cables, and electric tools that
are in good repair
Lockout / tagout recognition and
procedures
Using appropriate protective equipment
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Summary: Electrical Hazards
and Protection Measures
Hazards
 Inadequate wiring
 Exposed electrical parts
 Wires with bad insulation
 Ungrounded electrical systems
and tools
 Overloaded circuits
 Damaged power tools and
equipment
 Using the wrong PPE and tools
 Overhead powerlines
 All hazards are made worse in
wet conditions
Protective Measures
 Proper grounding
 Use GFCIs
 Use fuses and circuit
breakers
 Guard live parts
 Lockout/tagout
 Proper use of flexible
cords
 Close electric panels
 Training
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Installer Safety: Electrical
Summary
Electrical equipment must be:
 Listed and labeled
 Free from hazards
 Used in the proper manner
If you use electrical tools you must be:
 Protected from electrical shock
 Provided with necessary safety equipment
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Conclusions
 PV safety involves the safety of the workers
while installing the system and the safety of all
others who may come in contact with the
system after it is installed.
 OSHA regulations help keep workers safe.
 NEC requirements help ensure a safe system.
 PV installers should be trained in both OSHA
regulations and the NEC. Special attention
should be paid to fall protection.
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