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Masonry Electrical Safety Training by Rocky Mountain Masonry Institute
1. Focus Four Hazard Training
For Masonry Construction
Module 1 - Electrical Safety
Susan Harwood Grant Training Program
2. Disclaimer/Usage Notes
This material was produced under grant number SH-17793-SH8 from the Occupational
Safety and Health Administration, U.S. Department of Labor. It does not necessarily
reflect the views or policies of the U.S. Department of Labor, nor does mention of trade
names, commercial products, or organizations imply endorsement by the U.S.
Government.
Images shown may depict situations that are not in compliance with applicable OSHA
requirements. These photos are clearly marked as non-compliant.
It is not the intent of RMMI to provide compliance-based training in this presentation, the
intent is more to address Focus Four hazard awareness in the masonry construction
industry, and to recognize overlapping hazards present in many construction workplaces.
It is the responsibility of the employer, its subcontractors, and its employees to comply
with all pertinent rules and regulations in the jurisdiction in which they work. Copies of all
OSHA regulations are available from www.osha.gov. This presentation is intended to
discuss Federal regulations only. If this training is held in a state that is operating under
an OSHA-approved State Plan, State OSHA requirements for that state must be included
in the training. It is assumed that individuals using this presentation or content to
augment their training programs will be "qualified" to do so.
Developed under an OSHA Susan Harwood Grant, # SH-17793-SH8, by
the Rocky Mountain Masonry Institute, Denver, Colorado
3. SUBPART
K
Masonry Electrical Safety
Training Objectives
After completing this unit, you will:
– Be familiar with the basic concepts of
electricity.
– Understand the potential effects of
electricity on the human body.
– Be able to recognize common electrical
hazards associated with masonry work.
– Be familiar with electrical protective
devices.
– Be knowledgeable of safe work
practices.
1
5. SUBPART
K
Masonry Electrical Safety
3
Take Electricity Seriously
Electricity is the second leading
cause of death in construction.
Electrocutions make up 12% of
construction fatalities annually.
Over 30,000 non-fatal shocks occur
each year.
Over 600 deaths occur annually
due to electrocution.
Source: Bureau of Labor Statistics
6. SUBPART
K
Masonry Electrical Safety
Electrical Accidents
Leading Causes of Electrical Accidents:
–
–
–
–
–
–
–
–
–
–
Drilling and cutting through cables
Using defective tools, cables and equipment
Failure to maintain clearance distance of 10 feet
Failure to de-energize circuits and follow Lockout/Tagout
procedures
Failure to guard live parts from accidental worker contact
Unqualified employees working with electricity
Improper installation/use of temporary electrical systems
and equipment
By-passing electrical protective devices
Not using GFCI (ground fault circuit interrupters) devices
Missing ground prongs on extension cords
4
7. SUBPART
K
Masonry Electrical Safety
5
Hazards of Electricity
Shock – Most common and can cause electrocution or
muscle contraction leading to secondary injury which
includes falls
Fires – Enough heat or sparks can ignite combustible
materials
Explosions – Electrical spark can ignite vapors in the
air
Arc Flash - can cause burns ranging from 14,000
degrees f. to 35,000 degrees f
Arc Blast – In a short circuit event copper can expand
67,000 times. The expansion causes a pressure wave.
Air also expands adding to the pressure wave
8. SUBPART
K
Masonry Electrical Safety
Fundamentals of Electricity
Like Water In A Garden Hose
Resistance = Diameter of Hose
Example – Larger hose (less resistance),
more water flows
Voltage = Water Pressure
Example – 45 PSI
ter
low of Wa
F
Current = Flow Rate
Example – 15 gallons per minute
6
9. SUBPART
K
Masonry Electrical Safety
Fundamentals of Electricity
Electrical current is the flow of
electrons through a conductor.
A conductor is a material that allows
electrons to flow through it.
An insulator resists the flow of
electrons.
Resistance opposes electron flow.
7
10. SUBPART
K
Masonry Electrical Safety
Current Flows in a
Loop or Circuit
Circuits are AC
(alternating current) or
DC (direct current).
Current is usually AC.
AC current has five
parts:
(1) Electrical source
(2) HOT wire to the tool.
(3) The tool itself
(4) NEUTRAL wire returns
electricity from the tool
(5) GROUND
8
11. SUBPART
K
Masonry Electrical Safety
How Shocks Occur
Current travels in closed circuits
through conductors (water,
metal, the human body).
Shock occurs when the body
becomes a part of the circuit.
Current enters at one point &
leaves at another.
9
12. SUBPART
K
Masonry Electrical Safety
Shocks Occur in
Three Ways
Contact with both
conductors
Contact with one
conductor and
ground
With a tool: contact
with “hot” metal
part and ground (1),
(2) & (3)
10
13. SUBPART
K
Masonry Electrical Safety
Severity of the Shock
Severity of the Shock depends on:
– Amount of current
• Determined by voltage and resistance to
flow
– Path through the body
– Duration of flow through the body
– Other factors such as general health
and individual differences.
11
14. SUBPART
K
Masonry Electrical Safety
He sweats - and he dies...
Luling, La. - A man was electrocuted when his
sweat dripped into the electric drill he was using
to build a swing set in his backyard, the coroner
said.
Richard Miller was pronounced dead
Sunday at St. Charles Hospital, said David Vial,
St. Charles Parish coroner. Miller, 54, had been
using an electric drill in 90 degree heat, Vial said
Monday.
“Apparently the man was sweating
profusely,” Vial said. “He probably was pushing
against the drill with his chest and his
perspiration went into the drill itself and made a
contact.”
The Associated Press
12
15. SUBPART
K
Masonry Electrical Safety
13
Effects of Current Flow
More than 3 milliamps (ma): painful shock
More than 10 ma: muscle contraction
More than 20 ma: considered severe shock
More than 30 ma: lung paralysis - usually
temporary
More than 50 ma: possible ventricular
fibrillation (usually fatal)
100 ma to 4 amps: certain ventricular fibrillation
(fatal)
Over 4 amps: heart paralysis; severe burns
16. SUBPART
K
Masonry Electrical Safety
14
Using a 120 volt circuit and resistance
for wet & dry skin:
E=IR: Voltage=Current x Resistance
(Volts) (Amps)
(Ohms)
So: I=E/R
Dry Skin =120/100,000=.0012 amps
=1.2ma flowing through
body to ground
Wet skin =120/1000=.120 amps
=120ma flowing through
body to ground
Remember: 1 Amp = 1000 milliamps
18. SUBPART
K
Masonry Electrical Safety
Controlling Electrical Hazards
Employers must follow the OSHA
Electrical Standards (Subpart K)
Electrical installation
Subpart K includes four proactive
methods:
–
–
–
–
Electrical Isolation
Equipment Grounding
Circuit Interruption
Safe Work Practices
16
19. SUBPART
K
Masonry Electrical Safety
Electrical Isolation
We can be safe by keeping electricity
away from us. We can:
– Insulate the conductors.
• Example: The insulation on extension
cords.
– Elevate the conductors.
• Example: Overhead powerlines.
– Guard the conductors by enclosing
them.
• Example: Receptacle covers, boxes, &
conduit.
17
20. SUBPART
K
Masonry Electrical Safety
Insulating the Conductors
The first way to safeguard workers
from electrically energized wires is
through insulation.
Rubber and plastic is put on wires to
prevent shock, fires, short circuits
and for strain relief.
It is always necessary to check the
insulation on equipment and cords
before plugging them in.
Remember, even the smallest defect
will allow leakage!
18
22. SUBPART
K
Masonry Electrical Safety
20
Defective Cord Incident
Depicts hazardous condition
Worker attempted to
climb scaffold with
electric drill.
Drill’s cord was
damaged with bare
wires showing.
The bare wire contacted
the scaffolding.
The worker died!
23. SUBPART
K
Masonry Electrical Safety
Elevating the Conductors
The second way to safeguard workers
from electrically energized wires is by
elevating them.
Wires are often elevated by the power
company.
It is always necessary to check the
location of overhead lines before you
begin work each day.
Remember, never allow yourself, your
tools, or the materials you are working
with to be within 10 feet of energized lines!
Photo depicts hazardous condition
21
24. SUBPART
K
Masonry Electrical Safety
Working Near Overhead Lines
Clearance of worker and any
equipment, tools, materials, or
scaffold near uninsulated
lines is 10 feet!
Photo depicts hazardous condition
22
25. SUBPART
K
Masonry Electrical Safety
23
Overhead Line Incident
A worker was
attempting to
move mobile
scaffold.
Scaffold made
contact with
7200 volt line.
The worker died.
Photo depicts hazardous condition
26. SUBPART
K
Masonry Electrical Safety
24
Guarding the Conductors
The third way to safeguard workers
from electrically energized wires is by
guarding them.
Covers, boxes, and enclosures are
often put around conductors to prevent
worker contact.
It is always necessary to check that
electrical boxes and panels are covered
and free from missing “knock-outs”.
Remember, electric equipment
operating at 50 volts or more must be
guarded!
Photo depicts hazardous condition
29. SUBPART
K
Masonry Electrical Safety
Equipment Grounding
We can be safe by providing a
separate, low resistance pathway for
electricity when it does not follow
normal flow (ground prong).
Grounding gives the stray current
somewhere to go and keeps you from
becoming part of the circuit.
27
30. SUBPART
K
Masonry Electrical Safety
Can You Rely on Grounding?
Grounding will not work if the
electricity can flow through you more
easily than the ground. This can
happen when:
– Your tool doesn’t have a ground pin.
– You’re working in wet locations.
– You’re touching a metal object.
28
31. SUBPART
K
Masonry Electrical Safety
What Must be Grounded?
All circuits and
extension cords.
All noncurrent carrying
metal parts.
Portable & semi-portable
tools and equipment
unless double insulated.
29
33. SUBPART
K
Masonry Electrical Safety
31
Do Not Reverse Polarity
The prongs are different
sized so you can’t turn
the plug around. If you
do, the electrical fields
within the motor are always
energized. If there is
moisture present, the case
is likely to be “hot”. Even
with double-insulated tools,
you still could get a shock.
Photo depicts hazardous condition
34. SUBPART
K
Masonry Electrical Safety
Circuit Interruption
We can be safer by automatically shutting
off the flow of electricity in the event of
leakage, overload, or short circuit.
Ground Fault Circuit Interrupters (GFCI)
are circuit protection (or “overcurrent”)
devices that protect you, the worker.
Circuit breakers & fuses protect
equipment, not you, because they take
too much current & too much time to trip.
32
35. SUBPART
K
Masonry Electrical Safety
Circuit Protective Devices
Circuit Breakers and Fuses
– Only protect the building, equipment,
and tools from heat build-up!
– Never depend on circuit breakers or
fuses to prevent shocks!
Ground Fault Circuit Interrupter
(GFCI)
– Is the only device which will protect the
worker from shock and electrocution!
33
36. SUBPART
K
Masonry Electrical Safety
34
GFCI Protection
All temporary circuits are required to
have GFCI protection or:
– Equipment & cords must be included
in an Assured Equipment Grounding
Conductor Program
An extension cord is a temporary circuit.
Types of GFCIs: receptacle, circuit
breaker and portable
Must be wired correctly and tested.
37. SUBPART
K
Masonry Electrical Safety
How a GFCI Works
The GFCI detects
‘leakage’ of 4-6
milliamps & opens
the circuit in 1/40th
of a second.
It will work without
the ground plug
but not fast
enough if you are
the ground .
35
41. SUBPART
K
Masonry Electrical Safety
Assured Equipment Grounding
Conductor Program
Requires the following:
-Written program and specific procedures
-Program implemented by a Competent Person (one
who is capable of identifying existing and predictable
hazards in the surroundings or working conditions
which are unsanitary, hazardous, or dangerous to
employees, and who has authorization to take prompt
corrective measures to eliminate them.
-Equipment grounding conductors must be tested
(tools, extension cords, and circuits):
At least every three months for cords & tools
At least every six months for receptacles
Results recorded - equipment coded (colored tape)
39
43. SUBPART
K
Masonry Electrical Safety
Temporary Wiring
There must be separate circuits for
electric tools and lighting, each
labeled as such.
Light circuits do not require a GFCI.
– Unless used in a wet location.
Test branch circuits before use.
Maintain vertical clearances.
Insulate wires from their supports.
41
45. SUBPART
K
Masonry Electrical Safety
Extension Cords and Cables
Must be in good shape without splices.
Cannot be secured with staples, nails or
bare wire.
Must be protected from damage.
Must have a ground pin.
Should be inspected regularly and pulled
from service if defective.
Cannot be repaired with electrical or duct
tape. Must repair with heat-shrink sleeve or
bonding/vulcanizing tape to retain original
insulation properties.
Photos depict hazardous condition
43
46. SUBPART
K
Masonry Electrical Safety
Acceptable Cord Types
All cords must meet the National Electric Code’s
(NEC) requirement for Hard/Extra Hard type.
Look for markings stamped on cords.
Acceptable Cord Types
– Extra Hard Use Markings: S, ST, SO, STO
– Hard Usage Markings: SJ, SJO, SJT, SJTO
44
50. SUBPART
K
Masonry Electrical Safety
Temporary Lighting
All bulbs must be
guarded
No broken bulbs
or empty sockets
Not suspended
by wiring
Low voltage for
wet locations
Photos depict hazardous condition
48
51. SUBPART
K
Masonry Electrical Safety
Portable Generators
The frame of the
portable generator need
not be grounded if:
– the generator supplies
only cord and plug
connected equipment.
– The non-current carrying
metal parts of equipment
and the equipment
grounding conductor
terminals of the
receptacles are bonded
to the generator frame.
– GFCI is required if >5kV
or if generator provides
220V as well as 110V.
49
52. SUBPART
K
Masonry Electrical Safety
Safe Work Practices
Before work begins, the employer
must determine where exposed and
concealed electrical circuits are
located.
Once found, warning signs/labels
must be posted.
Workers need to know the location,
hazards, and protective measures.
50
53. SUBPART
K
Masonry Electrical Safety
Safe Work Practices
Competent Person determines if
performance of work could bring
contact with energy.
– Distance of the worker to the energy
source should be considered first.
– Tools, materials, and processes should
also be considered to see if they could
potentially shorten the safe separation
distance.
• Examples: Metal Ladders, Re-bar, Forklift,
Scaffold Frames, etc.
51
54. SUBPART
K
Masonry Electrical Safety
Safe Work Practices
Must not permit work near electric
circuits unless the worker is
protected by:
– De-energizing the circuit and grounding
it.
– Guarding it effectively by insulation.
– Other means (maintaining safe
separation)
De-energized circuits and equipment
must be locked/tagged out.
52
55. SUBPART
K
Masonry Electrical Safety
Safe Work Practices
No metal ladders for or near
electrical work.
No wet hands when plugging or
unplugging cords/equipment.
No raising or lowering tools by
the cord.
Unless equipment is designed
for it, cannot be used in damp
and wet locations.
Photo depicts hazardous condition
53
56. SUBPART
K
Masonry Electrical Safety
Electrical Safety
Common OSHA Citations:
– .404(b)(1)(i): Branch circuits: GFCI
protection/Assured Equipment Grounding
Conductor Program
– .404(f)(6): Grounding path
– .403(b)(2): Equipment installation and use
– .404(b)(1)(ii): GFCI
– .403(i)(2)(i): Guarding live parts
How can the hazards addressed by these
Standards best be corrected, controlled,
or eliminated?
54
57. SUBPART
K
Masonry Electrical Safety
55
Summary – Hazards & Protections
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 power lines
All hazards are made worse in
wet conditions
Damaged extension cords
Unqualified workers doing
electrical work
Protective Measures
Proper grounding
Use GFCI’s
Use fuses and circuit breakers
Guard live parts
Lockout/Tagout
Proper use of flexible cords
Close electrical panels by
Competent Person
Employee training
Ensure Competent Person on
site
Use proper approved electrical
equipment
Qualified person install
electrical devices
58. SUBPART
K
Masonry Electrical Safety
REVIEW QUESTIONS
True or False?
1. Shocks and Electrocutions are the most
common type of electrical accident and are
the fourth leading cause of worker deaths.
2. The human body will not conduct
electricity.
3. It takes at least 1 amp going through a
worker to kill them.
4. Insulation on extension cords & elevating
power lines are examples of protection
through isolation.
56
59. SUBPART
K
Masonry Electrical Safety
REVIEW QUESTIONS
True or False?
5. All portable and semi-portable tools and
equipment must be grounded unless
double insulated.
6. You, your tools, and the materials you are
working with, must never be closer than 3
feet of energized power lines!
7. Electric equipment operating at 50 volts or
more must be guarded!
8. All circuits and extension cords must be
grounded.
57
60. SUBPART
K
Masonry Electrical Safety
REVIEW QUESTIONS
True or False?
9. Circuit breakers and fuses are designed to
protect the worker from electrocution.
10. GFCI protection or Assured Ground
Continuity is required on all temporary
circuits.
11. Extension cords are not required to have
a ground prong when they are GFCIprotected.
12. It is OK to work on a circuit which has not
been de-energized.
58
Editor's Notes
Trainer's Notes:
Duration: One Hour
Demonstration Materials:
Extension cords (good, defective, household use only)
GFCI example types (receptacle, breaker, portable)
3. Short piece of 12-2 wire.
4. Jury-rigged items as may be available as bad examples.
Trainer's Notes:
This training module is not designed to teach you to work as a qualified electrician.
It is designed to help you recognize and avoid some of the Focus Four electrical hazards associated with masonry work.
If you spot problems on your job site, notify your supervisor.
Trainer's Notes:
The law requires your employer to follow these standards.Your employer also must ensure that you and you co-workers follow the safe work practices within the electrical standard.
OSHA standards are considered the bare minimum needed to protect the worker.
NEC requirements that directly affect employees in construction workplaces have been placed in the text of the OSHA standard.
Trainer's Notes:
Stress the importance of electrical safety.
Remind them not to underestimate the hazards associated with electricity. We sometimes become complacent about electrical hazards because we cannot hear, smell, or see electricity.
Ask participants if they have ever experienced an electrical shock.
Trainer's Notes:
Leading causes are usually viewed as “symptoms” to a deeper problem.
Often management and leadership problems (root causes) allow the leading causes to exist or form.
Ask the participants to name some root causes which might allow some of these leading causes to exist.
Trainer's Notes:
Ask the participants the difference between a shock and electrocution. (Electrocution means DEATH. )
Explain that shocks lead to other, secondary injuries such as falls due to the worker’s reaction.
Ask the participants for examples of how each of the accidents might occur.
Explain NFPA 70E which requires workers to stay at least 4 feet away from any exposed electrical devices
such as open disconnects and electrical panels with missing covers
Trainer's Notes:
Explain that most workers are exposed to 120 volts.
Explain that even with a constant 120 volts, the electric flow rate (Amperage) through the body will vary depending on how much Resistance it encounters.
Explain that the path through your body, your clothing, and whether or not your skin is wet will determine the resistance.
Amperage through you = Voltage divided by Resistance
Trainer's Notes:
Remind them that metals conduct electricity.
Explain that some metals, such as copper, are excellent conductors and are used as wire.
Explain that the human body will conduct electricity.
Explain that things like rubber, plastic, glass and ceramic are insulators. Further explain the sentence ‘Explain that things like
rubber, plastic, glass and ceramic are insulators.’ These materials are especially made to be insulators. For
example, rubber tires for vehicles are not insulators because of the steel belts and carbon black added to
color the tire black.
Trainer's Notes:
Explain that when a circuit works right, current flows through the HOT wire to the tool. It returns to the source through the NEUTRAL wire.
Explain that when something goes wrong with a circuit, it is called an electrical fault.
Explain that when things are right the GROUND has no current flow. A low resistance ground can
help protect the workers from an electrical injury. If there is a short in a piece of electrical equipment, the
current will take the path of least resistance. If the worker has a higher resistance than the ground, then the
current will flow through the ground.
Trainer's Notes:
Explain that the worst part of the body for current to pass through is the chest cavity. Question: WHY?
ANS. Current directly through the heart is most likely to cause heart fibrillation, that is, interruption of the tiny electrical current that determines the heart’s correct rhythm.
Technically, the heart’s electrical current is 2-3 micro-amps, or .000002-.000003 amps. Compare that to 20.0 amps in a regular 120 volt circuit – 1.0 amp = 1,000 milliamp = 1,000,000 micro-amp.
Trainer's Notes:
Use the12/2 wire with some of the outside sheathing removed for a visual aid.
Demonstrate the possible scenarios.
Trainer's Notes:
Ask to see a show of hands of those that have been shocked.
Remind them that the shock that startled them could very easily have been fatal under different circumstances.
Explain that there are too many variables to not take electricity seriously.
Trainer's Notes:
Ask the participants to read the incident.
Ask them if they ever pushed against a drill with their chest.
Ask them for suggestions on what could have prevented this incident.
Trainer's Notes:
Explain that when it comes to electricity and the human body’s inability to deal with it, we can no longer talk in terms of Amps and must use smaller units.
Explain that 1 Amp is equal to 1000 milliamps.
Explain that 1/20 of an amp (50 ma) going through the chest cavity can stop the heart and be fatal.
Ask them when the typical circuit breaker will trip ?
Trainer's Notes:
Point out the vast difference between wet skin resistance and dry skin resistance.
Remind the participants that often this alone can be the difference between a shock and an electrocution.
Also point out using this graphic OSHA’s requirement for guarding of live parts relates directly to the point at which (with reduced resistance) current becomes sufficient to cause an electrocution.
Trainer's Notes:
Trainer's Notes:
Explain that at a minimum, employers must follow the OSHA Electrical Standards.
Explain that these standards provide protection for using temporary wiring in construction.
Explain that all four proactive methods must be implemented for a safe site.
Installation
Guarding live Parts
Approval for use
Protection from damage
Electrical safe practices
Trainer's Notes:
Remind the participants that the whole purpose of electrical isolation is to prevent worker contact with electricity.
Covers shall be installed on all electrical devices, such as panels, disconnects, motor terminal boxes.
Trainer's Notes:
Explain that an insulator is any material with a high resistance to electric current.
Stress the importance of ensuring that the tools and equipment they use is free from insulation related defects.
Ask participants: How does insulation get damaged?
Trainer's Notes:
1926.405(g)(2)(iii) Splices (repaired)
1926.404(f)(6) Path to ground shall be continuous
1926.416(e)(1) and (2) Frayed and damaged extension
cords
1926.405(g)(2)(iv) Strain relief (explain the hazard)
Damaged and cut cord with exposed conductor.
Remind them of just how serious this situation is.
Ask them: What should they do if they see a cord like this on their site?
Trainer’s Notes:
Review the incident with the participants.
Ask them what caused the accident?
Ask them how it could have been prevented?
Use of GFCI would have prevented the accident. Even with the use of GFCI, there is an instant shock which could have resulted in a ‘fall’.
Trainer's Notes:
Ask them: How many different ways could you contact overhead lines working in the masonry business?
Assume all overhead lines are energized unless told by the electric company or a competent person.
Trainer's Notes:
Explain that power line contacts account for a large percent of electrocutions.
Stress the importance of the 10 foot rule.
Remind them that it also applies to the material they handle and the equipment they use.
Stress the fact that the power company is very willing to de-energize lines and work with the contractor.
Clearance also applies to secondary lines going to the house because the lines are usually old, cracked, or maybe even damaged which could
expose energized parts.
Trainer’s Notes:
Review the incident with the participants.
Ask them what caused the accident?
Ask them how it could have been prevented?
Always look over the jobsite before beginning work.
Trainer's Notes:
Explain that as little 50 volts has the ability to produce enough current flow across the chest to stop the heart within 6 seconds.
Remind them that most of the time they are dealing with at least twice that amount.
When masons need electric power, they need to use a qualified person.
The photo is a violation.
Abatement: Cover the hole with an approved cover.
Trainer's Notes:
1st hazard - No cover around receptacles leaves exposed energized 120 volt parts.
Abatement: Since box is outside, this would need a rain tight cover.
2nd hazard: This box needs to be secured and the non-metallic shield cable (romex) needs to be protected from damage.
Abatement: Mount box on wall, support romex, and protect from damage.
Trainer's Notes:
Stress the serious nature of these situations.
Ask participants if they have seen similar situations on their job sites.
Electrical Safety: As per NFPA 70E, workers should stay at least 4 feet from energized devices.
Abatement: The left photo needs covers. The electrical installation (in the photo on the right side) needs to be replaced with the proper
electrical equipment. It has too many hazards and can not be abated. It must be totally redone by a qualified person.
Trainer's Notes:
Explain that equipment grounding helps to safeguard the equipment operator in the event that a malfunction causes the metal frame of the tool to become energized.
Ground prong on the extension cord is very important. It provides a low resistance path to ground (or source).
Trainer's Notes:
Stress the importance of looking for the ground prong (or the designation for double-insulated) on all equipment, tools and cords.
If the resistance is equal in the ground and in the workers, the current will flow on both paths.
Trainer's Notes:
Explain the importance of a grounding.
Remind them that without a ground, in the event of a tool’s internal short circuit, their body will most likely become the ground.
Missing ground is a violation and will be cited.
Trainer's Notes:
Explain that devices which by-pass the ground prong on any piece of equipment, tool, or cord are extremely dangerous and not permitted on site.
Remind them that often these devices are referred to as “suicide plugs”. Show audience the devices called ‘suicide plugs.’
Make sure everyone sees that the ground prong has been removed from the plug on the right and that the cord should be removed from service.
Remind them of the potentially serious consequences of eliminating the ground path.
Trainer's Notes:
Remind them of the potentially serious consequences of eliminating the ground path. On a three-pronged plug often the other two prongs are the same size and with the ground pin removed, you can reverse the plug, thus reversing the polarity.
Some double insulated tools use a ground prong to ensure that reverse polarity will not occur.
Trainer's Notes:
Explain that fuses are designed to melt when too much current flows through them
Explain that circuit breakers are designed to trip open the circuit by electromechanical means.
GFCI protects people. GFCI are the only electrical devices to protect people. Branch circuits require GFCI protection. Not having
GFCI in branch circuits (extension cords) is a violation.
Trainer's Notes:
Explain the misconception that a fuse or circuit breaker will save their life in the event of accidental contact with electricity.
Stress that fuses and circuit breakers protect equipment, not people, and don’t protect against shocks and electrocutions!
GFCI are very important to protecting people. This can not be stated enough times. Make sure the trainer distinguishes between circuit
breakers, fuses, and GFCI.
Trainer's Notes:
Explain that unless you plug the machine, tool, or light directly into the building’s permanent wiring, it must be run through a GFCI, or must be included in an Assured Equipment Grounding Conductor Program..
Remind them that any and all extension cords must be GFCI- protected or color-coded for the Quarter in which they have been inspected by the Competent Person in charge of the Assured Equipment Grounding Conductor Program.
Show an example of GFCIs.
Assured Equipment Grounding Conductor Program is a very complicated program that takes a competent person to set up the program and
provide the training. All workers need to be trained in this program.
Trainer's Notes:
Explain that a GFCI is a fast-acting circuit breaker which senses small imbalances in the circuit caused by current leakage to ground and, in a fraction of a second, shuts off the electricity.
Explain that the GFCI monitors the current “going” to the tool and compares it to the current “returning”.
Explain that whenever it senses approximately a 5ma difference it shuts down the circuit in 1/40 of a second.
A GFCI does work if there is no ground, since it is working based on the difference in current between the two conductors. However, there is no protection against a dead short with no path to ground.
Further explain about strain relief. Further explain that if the neutral is pulled away, then there is not GFCI protection.
Trainer's Notes:
Discuss and demonstrate various types of GFCI equipment.
Explain how they can be wired incorrectly and have the indicator lights work but actually fail to protect.
Explain GFCI-protected receptacles in series.
Explain how often GFCI should be tested and how.
Trainer's Notes:
This would be a citable offense by OSHA.
Trainer's Notes:
Explain that the GFCI will work without the ground BUT without the ground YOU are still the best path to ground, so if there is a dead short,( like crossed wires), especially if anywhere near your heart, a shock and potential electrocution can still occur. REMEMBER, the GFCI trips at 4-6 milliamps, which is >1000 times the heart’s current. A shock can induce fibrillation BEFORE the GFCI trips.
Explain that GFCIs must be tested.
Explain GFCI’s can also be tested without a tester by plugging in a tool, such as a drill, running it and pressing the test button on the GCFI.
Explain that simply pushing the test button without a load (running tool) is not an accurate test. GFCI’s can be wired wrong and the test button will still operate.
All of the above testers will only test 120 volt circuits. They will not test the 220 volt circuit going to the brick saw. Remind audience to read
the instructions that come with the breaker.
Trainer's Notes:
Explain that OSHA does permit this option instead of GFCI protection.
Tell them that some contractors choose to do both.
Also if there is a possibility of damage to the electrical device, it must be taken out of service and tested (by a competent person) before being used again.
Competent person: One who is capable of identifying existing and predictable hazards in the surrounding or working conditions that are unsanitary, hazardous, or dangerous to employees and who has authorization to take prompt corrective measures to eliminate the hazards.
Trainer's Notes:
Discuss strain relief and checking the windings and bushings to the motor.
The tester used in this photo is a continuity tester.
Trainer's Notes:
Ask the student why it is important to have separate circuits for electric tools and lighting ?
Double insulated tools and equipment still need GFCI protection.
Trainer's Notes:
Explain to participants that although these make handy home-made extension cord ends, they are not approved for portable and temporary use.
Explain that the listing and labeling of the box requires it to be fastened to something.
Also, Romex is not flexible enough for temporary use, and with knock-outs missing there is additional opportunity for problems.
This violation will be cited by OSHA. Only approved boxes can be used as a splitter box.
Trainer's Notes:
Remind the participants how often cords are used on the site.
Ask them how cords can get damaged and how to protect cords from damage.
Explain the rating of cords and read a cord rating to them.
Demonstrate how to inspect a cord.
Extension cords can only be repaired by a qualified person.
Extension cords shall be heavy or extra heavy duty insulation which is stamped on the outer jacket. (see code on cord).
Extension cords can only be repaired if after being repaired the cord is equal or better than the original condition of the cord.
Trainer's Notes:
Pass around various pieces of acceptable cord types.
Ask participants to locate markings.
After participants have located markings, pass around a section of 2-wire household cord.
Trainer's Notes:
This cord should be pulled from service.
Remind them that splices are not permitted.
This is a violation of the OSHA Standards.
Trainer's Notes:
The extension cord on the left is a ‘hard, or extra-hard usage’ type.
The one on the right is not. Discuss the potential for exposure of the conductors.
Ask them why they think these flat molded cords are not permitted on site?
Explain to them that the yellow molded cord has the conductors molded into the outside covering only and does not have double the insulation.
The cord on the right is a violation of the OSHA Standards.
Trainer's Notes:
Ask the participants for their opinion of this kind of “jury-rigging” , given the very real possibility of electrocution?
If a compliance officer would see either of these homemade electrical devices, it would indicate that there is no competent person on this site. OSHA
violation.
Trainer's Notes:
Explain that even though most of the time temporary lighting is well out of the worker’s reach, often a piece of conduit, re-bar, and other materials are capable of making contact. Explain the importance of keeping systems in good shape.
The photos show OSHA violations.
Trainer's Notes:
It may be helpful to have an owner’s manual for a given generator to help explain generator safety.
Trainer's Notes:
Explain that having the physical environment in good shape (i.e., tools, circuits, equipment etc..) is only half of the safety equation. Safe work practices is the other half.
Need competent person.
Trainer's Notes:
Stress the importance of thinking through each operation to determine whether a tool, material or process will effect their proximity to an energy source.
Workers and equipment must be 10 feet from overhead lines. Competent person has the knowledge and the authority to correct hazards.
Trainer's Notes:
Remind them that they should not be exposed to energized unguarded electrical circuits.
Workers shall stay away, 4 feet or more, from exposed energized devices which are 600 volts or less. If panels and disconnects are
open, see a qualified person to correct the hazard.
Trainer's Notes:
Ask student if they can think of any additional safe work practices?
Ask them what type of ladders should be used around electricity?
Is there a competent person on this jobsite?
Trainer's Notes:
Review the Top Five Serious Citations
Ask the participants how each of the five hazards could be abated.
1926. 416(a)(1), and/or (2), and/or (3)
1926.416 (e)(1) and/or (2)
1926.20(b)(1)
1926.21(b)(2)
Trainer's Notes:
Stress the importance of thinking through each operation to determine whether a tool, material or process will effect their proximity to an energy source.
Trainer's Notes:
Answers:
1. TRUE
2. FALSE
3. FALSE - 1/20 of an amp (50 ma) going through the chest cavity can stop the heart and be fatal.
4. TRUE