4-5 Hours. Urgent Revision Work
jhayes
nfpa_70e_class.pptxNFPA 70E What Does It Mean To You?
NFPA 70E
Standard for Electrical Safety in the Workplace
Electrical Incidents
Injuries & Fatalities
Department of Labor
9,600
Shock and Burn Injuries
Each Year
Approximately One Fatality Each Day
Electrical shocks do not always end in death!
Severe Burns
Scarring
Tissue Death
Lost Limbs
Blindness
Hearing Loss
And Other Serious Injuries
What Does OSHA Expect From You
As A Safety Professional?
A Great Deal!
29 CFR 1910.269(a)(2)(iii)
The employer shall determine, through regular supervision and through conducted on at least an annual basis, that each employee is complying with the safety-related work practices required by this section; and Note: OSHA would consider that tasks that are performed less often than once per year to necessitate retaining before the performance of the work practices involved.
29 CFR 1910.332
The training requirements contained in this section apply to employees who faced a risk of electric shock that is not reduced to a safe level by the electrical installation requirements of 1910.303 through 1910.308.
29 CFR 1910.301 Through .308
Basically paraphrases the National Electric Code (NEC).
29 CFR 1910.269 (a)(2)
Employees shall be trained in and familiar with the safety related work practices, safety procedures and other safety requirements in this section that pertain to their prospective job assignments. Employees also be trained in and familiar with any other safety procedures (such as whole and manhole rescue) that are not specifically addressed by this section, but that are related to their work and are necessary to their safety.
Installation Account for 80% of the Citations
And Account for 9% of the Accidents
Safe Work Practice Issues Were Cited 20% of the Time
Account for 91% of All Electrical Related Accidents
There are five primary factors that determine the severity of an injury from an electrical arc:
• Distance from the arc
• Absorption coefficient of the clothing worn
• Arc temperature
• Arc duration
• Arc length
Let’s take a closer look at each one of these items so you can better understand how to protect your workers or yourself.
Distance from the Arc
Incident Energy
Body Position
Inverse Square
The heat of an electrical arc is referred to as the “incident energy.” This is because the heat is made up of the radiated heat (infrared) and convection heat (heat flow through air). Incident energy decreases by the inverse square of the distance as a person moves away from an arc source. A simpler way to state this is that as a person moves away from an arc, the heat will decrease rapidly.
Body position is a primary factor to consider when performing energized work. A person should stand as far from the device as practical, while still being able to perform the work effectively.
If incident energy decreases by the inverse square of the distance moving away from an arc source, it will increase by the square of the distance as the distance decreases. It only takes a small change in the distance to make a large change in the incident energy. The standard working distance for work on systems operating at less than 600V is typically 18 in., while 2.4kV to 15kV power systems typically have a 36 in. working distance.
14
Absorption Coefficient of Clothing Worn
Type and Fabric Weight
Flammable or Non-Melting Underlayers
Cotton
Wool
silk
Or Arc-Rated Underlayers
Clothing under arc-rated clothing reduces the heat to the body by approximately 50%.
The type and fabric weight of clothing being worn affects the heat that is transferred to the body. NFPA 70E recommends wearing either flammable, non-melting clothing as underlayers (cotton, wool, or silk) or arc-rated underlayers for additional protection. The general rule of thumb is that each layer of clothing worn under arc-rated clothing reduces the heat to the body by approximately 50%. Flammable underlayers do not increase the arc rating of a clothing system, but will reduce the probability of a burn underneath arc-rated clothing.
16
Arc Temperature
Temperature of an Electrical Arc
Megawatts of Power
Megawatts (watts x 1,000,000)
A 3-phase, 480V fault with 50,000A of short circuit current will consume 23MW of power.
The temperature of an electrical arc is mostly determined by the megawatts of power being consumed by the arc. Megawatts (watts x 1,000,000) is a tremendous amount of energy. A 3-phase, 480V fault with 50,000A of short circuit current will consume 23MW of power. The heat from an electrical arc vaporized the copper in this circuit breaker.
21
Arc Duration
Overcurrent Protective Devices
Arc duration is the second most-critical injury factor in an arc flash event.
Overcurrent protective devices shall be maintained in accordance with the manufacturers' instructions or industry consensus standards.
Poorly maintained circuit breakers and other overcurrent protective devices (OCPDs) are unreliable.
NFPA 70B, Recommended Practice for Electrical Equipment Maintenance
ANSI/NETA MTS-2015, Standard for Maintenance Testing Specifications for Electrical Power Equipment and Systems
Keeping overcurrent protective devices calibrated reduces the duration of the arc. The arc duration is the second most-critical injury factor in an arc flash event. Incident energy is proportional to time. If a person is exposed to an arc flash for 0.08 sec, they would receive twice the incident energy as an arc of the same magnitude that lasted 0.04 sec. This is why the NFPA 70E Technical Committee added Sec. 205.4 to the standard, which states: “Overcurrent protective devices shall be maintained in accordance with the manufacturers' instructions or industry consensus standards.”
Poorly maintained circuit breakers and other overcurrent protective devices (OCPDs) are unreliable. If an OCPD malfunctions, it will increase the time it takes to clear and extinguish the fault. NFPA 70B, Recommended Practice for Electrical Equipment Maintenance, and ANSI/NETA MTS-2015, Standard for Maintenance Testing Specifications for Electrical Power Equipment and Systems, should also be consulted to develop an acceptable maintenance program.
22
Arc Length
Arc length becomes a factor at higher voltages (i.e., greater than 600V).
Low-voltage power systems less than 208 V cannot normally sustain an electrical arc, as arc resistance causes a voltage drop of approximately 75V per inch to 100V per inch.
The arc length becomes a factor at higher voltages (i.e., greater than 600V). It has been demonstrated that with all other factors being the same a longer arc creates more incident energy than a shorter arc. Low-voltage power systems less than 208 V cannot normally sustain an electrical arc, as arc resistance causes a voltage drop of approximately 75V per inch to 100V per inch. Even though high-voltage electrical systems present the greatest risk of an arc, low-voltage systems can also suffer catastrophic failures.
24
Assignment
Becker Manufacturing
Terminated the company Safety Supervisor
You have been hired
Your first tasked is to compose a proposal to fix the company’s problem by using NFPA 70E
Electrical issues over the past three years:
Employee just died from electrocution
The company has paid over $100,000 in OSHA fines
The company has also paid approximately $95,000 in workers comp
Hospital and doctors fees equal $183,000
The company has seen it’s name all over the national media
Becker Manufacturing annual net profit: $1,750,000
The proposal must be a letter addressed to Cris Burgin, Corporate Safety Director
Defend your proposal with:
Facts and Figures
Bar Graphs or Pie Charts – Does not count in the four page minimum
Use Headings and Sub-Headings to highlight your data and research
You must use appropriate Grammar
Do not use contractions (don’t, they’re, couldn’t, ect.)
In-Text citations for all references
Worth: 100 points
Four Page Minimum
Three References Minimum
APA Format (Strict)
You may work in a team of no more than two
Due April 11th, 2017
If your/team proposal is not completed and submitted by the due date, you will be fired and receive a ZERO for your grade!
The best proposal will receive a 25 point bonus!
Noel Studio paperwork will earn you a 5 point bonus.
FYI: Grading is going to be extremely strict!
Write a problem statement—the main question your report will answer.
The problem should be:
• worded very precisely, and
• realistic given the resources and availability of data.
Determine the factors
Factors are the subtopics your report will address. Turn each factor into a question the report will answer. These sub-questions should be mutually exclusive and fit under the “umbrella” of the statement of the problem
Recommendations should be SMART:
• Specific actions that are…
• Measurable
• Agreeable
• Realistic
• Time bound
Helpful Hints
Issues to Consider:
Cost of Training
Cost of New PPE
Cost of Appropriate Tools
Cost of Hiring New Electrician(s)
Helpful Hints
