Electrical Safety for Engineering

1. EHS DEPARTMENT
Electrical Safety Training
for Engineering
2017-18

2. EHS DEPARTMENT
Safety Briefing - Outline
Definitions
Effects of Shock
Electrical Fire Hazards
Sobering Statistics
Regulations & Standards
SCU Electrical Safety Program
Electrical Safety – Best Practices
Insulated Gloves & Equipment
Use of Extension Cords & Plug Strips
Emergency Procedures

3. EHS DEPARTMENT
Electrical Safety
Definitions:
– Qualified Person – One who has received training in and has demonstrated
skills and knowledge in the construction and operation of electric equipment
and installations and the hazards involved
– High Voltage – OSHA defines high voltage as >600 volts (The 2012 Formula
Hybrid Rules define high voltage as containing or producing greater than 30
volts – assumes these are high current systems used to power the car’s drive
motor)
– Exposed – Capable of being inadvertently touched. Applies to parts that are
not suitably guarded, isolated, or insulated. Examples include terminal
contacts or lugs and bare wiring
– Lockout/Tagout (LOTO) – The placement of a lockout device and tag on an
energy isolating device according to procedure ensuring that the energy
isolating device and the equipment being controlled cannot be operated until
the lockout device is removed

4. EHS DEPARTMENT
Definitions:
– Circuit – a complete path for the flow of current. A path for the flow of
electrical energy between points with different energy levels
– Ground – a physical, conductive, electrical connection to the earth
– Ground-Fault Circuit Interrupter (GFCI) – a device intended for the protection
of personnel that deenergizes a circuit when a current to ground is detected
– Energized Work – work performed on or near exposed electrical circuits,
components or systems while there are energized
– Disconnecting means – device(s) used to disconnect conductors from the
electrical source such as a switch or circuit breaker
Electricity Safety

5. EHS DEPARTMENT
Electrical Safety
Types of Electrical Hazards:
– Electric shock
– Thermal Burns
– Fires
– Falls
Electrical Injuries Can Result in Severe Injury or Death
Low Voltage Does Not Mean Low Hazard!

6. EHS DEPARTMENT
Received When Current Passes
Through the Body
Severity of Shock Depends on:
– Path of the current (next slide)
– Amount of current (more to follow)
– Length of time – the longer the exposure
the more potential damage
– Contact area and pressure - the larger
the area the higher the potential for
damage
– Skin condition – dry skin can have
thousands of ohms of resistance, while
wet skin will have little to no resistance
Electrical Shock

7. EHS DEPARTMENT
Resistance of the Human Body
Along
leg
Along
arm
Ear to
ear
Hand
to foot
Hand
to hand
Along arm
No vital organs
125 Ω
Along leg
No vital organs
150 Ω
Hand to hand
Crosses heart
400 Ω
Hand to foot
Crosses heart
600 Ω
Ear to ear
Crosses brain
100 Ω
Which pathways would be
the MOST lethal?

8. EHS DEPARTMENT
Effects of Increasing Amperages on the Body
Alternating
Current
(mA)
Direct
Current
(mA)
Effect/feeling Incident severity
150 lb Male 150 lb Male
0.4 1 Slight sensation None
1.1 5.2 Perception threshold None
1.8 9 Shock not painful None
3 – 10 62 Shock painful Spasm, indirect injury
16 76 Muscle clamps source Possibly fatal
20 – 30 170 Respiratory arrest Frequently fatal
75 375 >5-s vent. fibril. Possibly fatal
100 500 >3-s vent. fibril. Possibly fatal
1000 1300 >0.03-s vent. fibril. Possibly fatal
4000 -- Cardiac arrest Possibly fatal
5000 -- Organs burn
Fatal if it is a vital
organ
- This and the next two slides summarizes the effects of Alternating Current
(AC) and Direct Current (DC) in milliamps (mA) through intact dry skin on a
150-pound male - effects may be more or less severe depending on the
weight, size, and body composition of the person
- The current values are represented as they pass through the body
- The National Electrical Code (NEC) considers 6 mA to be the safe upper
limit for shock protection

9. EHS DEPARTMENT
Effects of Increasing Amperages on the Body
Alternating
Current
(mA)
Direct
Current
(mA)
Effect/feeling Incident severity
150 lb Male 150 lb Male
0.4 1 Slight sensation None
1.1 5.2 Perception threshold None
1.8 9 Shock not painful None
3 – 10 62 Shock painful Spasm, indirect injury
16 76 Muscle clamps source Possibly fatal
20 – 30 170 Respiratory arrest Frequently fatal
75 375 >5-s vent. fibril. Possibly fatal
100 500 >3-s vent. fibril. Possibly fatal
1000 1300 >0.03-s vent. fibril. Possibly fatal
4000 -- Cardiac arrest Possibly fatal
5000 -- Organs burn
Fatal if it is a vital
organ
- At the 3 to 10 mA AC (62 mA DC) the electrical shock may cause an indirect
injury such as a fall and at this level the shock is painful
- At 16 mA AC (76 mA DC) a person may not be able to let go of the electrical
source and at this point the shock may be fatal

10. EHS DEPARTMENT
Effects of Increasing Amperages on the Body
Alternating
Current
(mA)
Direct
Current
(mA)
Effect/feeling Incident severity
150 lb Male 150 lb Male
0.4 1 Slight sensation None
1.1 5.2 Perception threshold None
1.8 9 Shock not painful None
3 – 10 62 Shock painful Spasm, indirect injury
16 76 Muscle clamps source Possibly fatal
20 – 30 170 Respiratory arrest Frequently fatal
75 375 >5-s vent. fibril. Possibly fatal
100 500 >3-s vent. fibril. Possibly fatal
1000 1300 >0.03-s vent. fibril. Possibly fatal
4000 -- Cardiac arrest Possibly fatal
5000 -- Organs burn
Fatal if it is a vital
organ
- Shocks of 5 or more second duration at 75 mA AC (375 mA DC) can result in
ventricular fibrillation (heart stops beating) and are possibly fatal
- Note: These current values are in MILLIAmps - there are 15 amps
(15,000 mA) available from a typical wall socket – these levels are
thousands of times less than that!

11. EHS DEPARTMENT
Electrical Fire Statistics:
– According to the National Fire Protection Association there
were 115,500 non-residential structural fires from 2005 to 2009
Typical Causes:
– Overloaded circuits
– Undersized wiring
– Loose connections
Electrical Fire Hazards

12. EHS DEPARTMENT
Sobering Statistics – In the US between 2003
& 2007 electrical contact resulted in:
1,200 fatalities 13,150 lost time injuries
An estimated 2,000 workers are treated for
burns due to electric arc flash each year

13. EHS DEPARTMENT
Electrical Safety Regulations
Design safety
standards Safety related work
practices
Safety related maintenance
requirements
Regulations cover:

14. EHS DEPARTMENT
Electrical Safety Standards
Consensus standard
– Updated every three years
Focus on worker safety standards to
protect against:
– Shock hazards
– Arc flash/blast hazards
Establishes:
– Safe work practices
– Personal Protective Equipment
(PPE)

15. EHS DEPARTMENT
Electrical Safety – Cal/OSHA
Regulations
Only qualified persons may perform work on electrical
equipment or systems
- Received instructions on work techniques and understands the
hazards of the work
Energized (Live) electrical work only allowed :
- On systems operating at less than 50 volts
- The regulations assume these are low current (low hazard) control
voltage systems
- When performing troubleshooting and testing
- Systems must be energized to be able to troubleshoot
- Will cover in more detail in later slides

16. EHS DEPARTMENT
Electrical Safety – Cal/OSHA
Regulations
Energized parts operating over 50 volts must be guarded
from contact:
- In cabinets or other approved enclosures
- Covered with non-conductive materials
- Properly insulated
Insulating a connector with electrical tape

17. EHS DEPARTMENT
Electrical Safety – Cal/OSHA
Regulations
When energized work is allowed:
Requires suitable personal protective
equipment & tools
- Safety glasses, rubber insulating gloves,
insulated tools
- Protection from electrical arcs
- Requires use of insulating barriers or
materials to prevent accidental contact
with energized parts
- Requires use of suitable barricades and
warning signs to prevent unauthorized
personnel from accessing
Note the use of a Plexiglas
barricade and warning sign in this
R&D set-up to prevent accidental
contact with energized
conductors operating over 50
volts

18. EHS DEPARTMENT
Electrical Safety – SCU Electrical
Safety Program
SCU’s Electrical Safety Policy
Electrical work on or around energized electrical parts, circuits or
equipment is performed only when necessary, and then only
after every alternative means to carry out de-energized work has
been considered and eliminated, and to establish safeguards that
will identify and control all hazards encountered in testing,
maintenance, service and all other work involving exposure to
live electrical parts at SCU.
Link to SCU Electrical Safety Program

19. EHS DEPARTMENT
Electrical Safety Program -
Energized (Live) Electrical Work
What is “Energized Electrical Work”?
– Work within 42 inches of energized and
exposed parts (Referred to as the Limited
Approach Boundary in NFPA 70E)
– Working on energized, exposed parts
that are capable of being touched or
approached where a shock could occur
Two categories of “Working On”
– Diagnostic - such as using a voltage
meter to test a circuit
– Repair – such as making or tightening a
connection

20. EHS DEPARTMENT
Energized electrical work IS NOT:
– Equipment that has been de-
energized and isolated, locked-out
and tested (Note: This may require
the use of PPE if there is a hazard
when de-energizing)
– Parts that are guarded to prevent
accidental contact
Electrical Safety Program -
Energized (Live) Electrical Work

21. EHS DEPARTMENT
Electrical Safety – SCU Electrical
Safety Program – Live Work
Establishes 3 Hazard Classes that Apply to School of Engineering
– Class A – Low hazard: Systems < 50 volts & < 1,000 watts
 Injury not likely
 Wear safety glasses
 Both “Diagnostic” and “Repair Work” permitted
– Class B – Medium hazard: Systems 50 to 300 volts and Systems
< 50 volts but over 1,000 watts
 Potential for severe injury/death, low arc flash hazard
 Wear safety glasses and insulating gloves
 May only perform “Diagnostic Work” - No “Repair Work”
Permitted
 Note that student projects may fall into this class of electrical
work

22. EHS DEPARTMENT
Electrical Safety – SCU Electrical
Safety Program – Live Work
– Class C – Hazardous: Systems 300 to
600 volts
 Potential for severe injury/death, moderate
arc flash hazard
 All energized work to be performed by a
qualified electrician – No “Diagnostic” or
“Repair” Work Permitted
 All “Repair” work would need to be justified
and require an Energized Electrical Work
(EEW) permit and may only be
performed by a licensed electrical
contractor
Establishes 3 Hazard Classes that Apply to School of Engineering
Must be a qualified electrician to perform

23. EHS DEPARTMENT
Electrical Safety – SCU Electrical
Safety Program
Achieve & Verify a Zero Energy
State before starting work
– Disconnect the power source and
ensure all capacitors have reached
a zero energy state
– Test to verify a zero energy state
– Ensure power isolation is under
your control or is locked-out
Your Goal Should Always be:

24. EHS DEPARTMENT
Electrical Safety – SCU Electrical
Safety Program
Treat Electrical Systems as Energized Until Tested
– Wear appropriate PPE when performing testing
– Always use appropriately rated test equipment and verify the
equipment is working properly
Three step process:
1. Test on know source to ensure meter is working
2. Test circuit of interest
3. Test on know source to ensure meter is still working
– Operator must be familiar with the operation of test equipment

25. EHS DEPARTMENT
Electrical Safety - Recommended Best
Practices
Safety Rules Cover:
–Participant Requirements
–Design Requirements
–Work Practices
–Rules of Conduct and General Rules
Establishes a Rules and Safety
Officer (RSO)
–Responsible for Team Safety
Program is Project Focused
Many are Based Upon Formula Hybrid Electrical Safety
Rules

26. EHS DEPARTMENT
Electrical Safety - Recommended Best
Practices
– Understand voltages and
amperages involved
– Establish project resource needs
– Establish work practices
– Establish roles and responsibilities
– Determine training requirements
– EHS involvement as needed
Student Projects - Review in Early Development Stage:

27. EHS DEPARTMENT
Electrical Safety – Recommended
Best Practices
When Energized Medium Hazard (Class B Work) Conductors or
Parts are Exposed and Present
Note: 30 volts and above is considered “High Voltage” in the Formula
Hybrid project because systems over 30 volts are typically high current
and meet the Class B definition for systems operating over 1,000 watts
– Only qualified electrical contractors may perform energized repair work on
these systems
– Work is limited to trouble shooting and testing or other work within 42” of
exposed conductors
– Isolation (guarding) of energized conductors should be accomplished
whenever possible to minimize the risk of accidental contact

28. EHS DEPARTMENT
Electrical Safety – Recommended
Best Practices
When Energized Medium Hazard (Class B Work) Conductors or
Parts are Exposed and Present (con’t)
Use Engineering Controls to Eliminate Class B Work…for example:
– During 2013 Formula Hybrid project, the drive battery was designed in
subassemblies that were connected via remotely activated switches.
– This design allowed repair work to be performed on each subassembly
independently since each subassembly operated below the 30 volt
threshold.
– The remote switches would only be activated, and the full energy potential
of the drive battery achieved, once all connections were properly guarded
and isolated.

29. EHS DEPARTMENT
Electrical Safety – Recommended
Best Practices
When Energized Medium Hazard (Class B Work) Conductors or
Parts are Exposed and Present (con’t)
– Project Advisor and/or Sponsor and at least two team members must be
present during energized work
– No other work should be performed within 10 feet of energized work
– The area is to be posted with a “Danger High Voltage” sign
– Use insulated tools and electrical gloves (always wear eye protection)
– Maintain good communication between team members
– All Team Members understand the work tasks and their responsibilities
– Anticipate Unexpected Events

30. EHS DEPARTMENT
Electrical Safety – Recommended
Best Practices
For Projects with Class B Work – Assign Responsibilities for:
 Maintaining System Design Documentation
 Maintaining Electrical Component Documentation
– Have manufacturer’s documentation and information available on all
components of the electrical system
 Team Safety
– Enforces use of safety glasses and other safety equipment
– Control of shock hazards such as charging equipment and accessible
high energy (> 1,000 watt) sources
– Helps establish and enforce safe working practices (energy isolation,
clean work area, shop safety, etc)

31. EHS DEPARTMENT
Electrical Safety – Hybrid Formula
Best Practices
Electrical Design Elements
– Segregate high voltage (energy > 1,000 watts) systems from low voltage
power systems via physical separation
– Identification (labeling, wire color different between high & low voltage
circuits, connections, etc)
– Isolation (guarding) of energized conductors (no exposed connections)
– Use of proper fusing located as close as possible to energy source
– Use GFCI to protect any high voltage circuits (shall not re-set
automatically and shall provide a visual trip indication)
– Maintain proper grounding
– Provide strain relief and proper protection of wiring insulation

32. EHS DEPARTMENT
Insulated Gloves & Equipment
– Equipment rated based on voltage to be
encountered
– Electrical Gloves:
 Visual inspection before each use
 Resistance testing semi-annually by company
certified to conduct lab testing in accordance
with ANSI specifications.
 Records must be kept of testing
– Insulating Blankets – Tested every 12
months

33. EHS DEPARTMENT
Inspection of Electrical Gloves
Cracking
and cutting
Snags / Pinholes
Chemical attack
(oils, etc.)
Gloves are your primary defense against electrical shock, and
you need to take care of them so they can do their job.
When you do your glove inspections, you should look for:

34. EHS DEPARTMENT
Inspection of Electrical Gloves
Never fold or compress
your gloves
UV checking (sun damage)
Never leave gloves exposed to prolonged sunlight which can cause
UV checking
Never fold or compress your gloves when they are being stored,
the folded point creates a strain by stretching the rubber

35. EHS DEPARTMENT
Inspection of Electrical Gloves
Test for pinholes by manually inflating the glove by rolling the cuff
tightly to trap air inside, then apply pressure to areas of the glove
to listen/feel for escaping air
Leather protective gloves should be worn over insulating gloves
with the leather glove extending at least 1 inch beyond the wrist
The insulating glove shall extend at least 1 inch beyond the leather
glove
Pinhole test

36. EHS DEPARTMENT
Personal Protective Equipment (PPE)
Wear PPE when Required by:
– Shop Safety Rules (Closed toed shoes, long pants and safety glasses
are typically the minimum PPE required)
– Equipment Specific Safety Rules
– Established Program Rules
Minimum Expectations
– Clothing – No loose clothing or long hair when working with power tools
or exposed rotating equipment. Long pants, closed-toe shoes and no
exposed skin on legs required for all labs and shops on campus. Flip
flops and shorts are not allowed.
– Eye Protection – When using hand or power tools, electrical work, using
hazardous materials, when working in posted areas, etc.
– Hearing Protection – Whenever using high noise producing equipment or
working in high noise areas.

37. EHS DEPARTMENT
Extension Cords
– Must not be run through holes in ceilings, walls,
floors, windows, or doorways, or attached to
building surfaces
– Are only for temporary use such as for
maintenance and construction activities
– Must be equipped with a grounding conductor
– Appropriate conductor size for the load – use only
heavy duty extension cords
– Must be energized from an approved receptacle
(not plugged into a power strip or another
extension cord)
Electrical Safety – Use of Extension
Cords

38. EHS DEPARTMENT
Power Strips
– Light duty power strips are to be
used to power low current
equipment such as computers and
monitors
– Power strips must not be used to
power high current equipment such
as microwaves & refrigerators
– Must be plugged directly into an
approved receptacle (not plugged
into an extension cord or another
power strip – this practice is called
daisy chaining and can result in
overloaded circuits and fires)
Electrical Safety – Power Strips
Daisy chained power strips

39. EHS DEPARTMENT
SCU Campus Safety x4444 (408-554-4444) or 911
Student injuries and incidents must be reported – notify your
faculty advisor or Lab/Shop Manager immediately.
Emergency Procedures

40. EHS DEPARTMENT
Course Completion
 Now that you have read the course slides, you must
complete the quiz.
 Upon completing the quiz, click on the Submit Quiz
button. A score of 90% or better is required to
pass.