ARC FLASH HAZARD OVERVIEWPresented August 13, 2015WWOA – Lake Michigan Districtby Mead & Hunt, Inc.

ARC FLASH EXPERIENCE

Christopher J. DeWaal, MS, MEM, PE, LEED AP, HACCP How did I get involved? A client had an electrical incident

that resulted in injury in 1998 and I was asked to help make their work environment safer.

Engineers’ Thought Process: Will it work? Can we afford it? Safety . . . ? This is the law! Wisconsin Administrative Code

Chapter A-E 8.

COST OF UNSAFE SYSTEM

Liability Costs 1999 Case Study by EPRI for CapSchell put the cost per

incident (death) at $15.75 million 1998 National Electrical Contractors Association study put

the cost per incident (injury) at $6 million Lost time, medical bills, lawyer’s fees

SO WHAT?

How common are electrical accidents?According to : NFPA 70E-2004, of the 350 Deaths in 2003

because of electricity, 50% were by arc flash CapSchell, there are 5-10 arc flash events

every day in the US, resulting in 1-2 deaths per day

NFPA 70E-2012, more than 2000 people are admitted to burn centers per year because of arc flash

WORKPLACE FATALITY STATISTICS

ELECTRICAL CURRENT EFFECTS ON THE BODY

Estimated Effects of 60 Hz AC Currents – Shock

WHAT IS ARC FLASH?

It is not electrocution or shock. Arc Flash is the energy produced

in an electrical circuit or electrical piece of equipment when an arc is produced.

WHAT CAUSES ARC FLASH?

Worker’s tools in contact with live parts Squirrel between transformer bushings Other conductive material in area

ARC FLASH EFFECTS

According to Bussmann research, a fault producing 41 MVA will result in a temperature of 35,000 degrees F and up to 2,000 lbs./sq.ft. of pressure Surface of the Sun: 5k – 9k degrees F 3rd Degree Burn: 155-175 degrees F for 1

second Eardrum Rupture: 720 lbs./sq.ft.

ELECTRICAL SAFETY RULES

NFPA 70E – Standard for Electrical Safety Requirements for Employee Workplaces - 2015 Installation Methods Safe Usage of Electrical Equipment Lock-Out, Tag-Out Arc Flash Limits of Approach

WORKER SAFETY RESPONSIBILITY

NFPA 70E 105.3 RESPONSIBILITY “The employer shall provide the safety-related work practices

and shall train the employee, who shall then implement them.” Your safety is your responsibility!

ELECTRICAL SAFETY PROGRAM

NFPA 70E 110.1 ELECTRICAL SAFETY PROGRAM Created and maintained by the employer Must “consider condition of maintenance of electrical equipment

and systems” – 110.1(B) Must “provide an awareness of the potential electrical hazards” –

110.1(C) Annex E gives examples

ELECTRICAL SAFETY PROGRAM

NFPA 70E 110.1(G) RISK ASSESSMENT PROCEDURE1. Identify hazards2. Assess risks3. Implement risk control according to hierarchy of safety controls:

1) Elimination2) Substitution3) Engineering Controls4) Awareness5) Administrative Controls6) PPE

ELECTRICAL SAFETY PROGRAM

NFPA 70E 110.1(H) JOB BRIEFING “Before starting each job, the employee in charge shall conduct a

job briefing with the employees involved.” NFPA 70E 110.1(I) ELECTRICAL SAFETY AUDITING Program audited every 3 years Field work (LOTO, Arc Flash) audited every year Audits shall be documented

TRAINING REQUIREMENTS

NFPA 70E 110.2(A) & (B) The training requirements contained in this section shall apply to

employees exposed to an electrical hazard when the risk associated with that hazard is not reduced to a safe level by the applicable electrical installation requirements.

Training can be classroom, on-the-job or a combination. NFPA 70E 110.2(C) – EMERGENCY RESPONSE TRAINING Employees responsible for responding shall be trained in CPR,

AED and first aid. Training shall be verified annually and documented

QUALIFIED & OUTSIDE PERSONNEL

Qualified Person (NFPA 70E, 110.2(D)(1)) NFPA 70E 110.3(A), (B) & (C) Host Employer: Must inform contract employers of known hazards covered

by NFPA 70E, give information about the installation that the contractor needs to made the assessments covered by NFPA 70E and report observed violations of this standard by contract employees to the contract employer

Contract Employer: Must inform contract employees of known hazards covered by NFPA 70E as directed by host, insure that contract employees follow the work practices required by NFPA 70E and the host employer, and report unique hazards or hazards not mentioned by the host employer to the host employer.

All meetings must be documented.

NFPA 70E ARTICLE 120

Verification of an Electrically Safe Work Condition – 120.11. Determine all possible sources of electrical supply, check

applicable, up-to-date drawings2. Open the disconnecting device(s)3. Visually verify operation of disconnecting device(s)4. Apply lockout/tagout devices (LOTO: 120.2 – 15 pages)5. Test each phase conductor or circuit part phase-to-phase and

phase-to-ground6. Ground phase conductors if induced or backfed electrical

energy could exist (120.3)

NFPA 70E ARTICLE 130

Work Involving Electrical Hazards 130.2: “Energized electrical conductors and circuit parts shall

be put into an electrically safe work condition” unless:1. De-energizing introduces additional hazards or increased risk

(life support systems, emergency alarm systems, hazardous location ventilation), or

2. Is infeasible in a de-energized state due to equipment design or operational limitations (diagnostics, testing, start-up, troubleshooting and work on circuits that form part of a continuous process).

NORMAL OPERATION

130.2 (A)(4): “Normal operation of electric equipment shall be permitted where all of the following conditions are satisfied:1. The equipment is properly installed.2. The equipment is properly maintained.3. The equipment doors are closed and secured.4. All equipment covers are in place and secured.5. There is no evidence of impending failure.”

NFPA 70E ARTICLE 130

130.2(B): Energized Electrical Work Permits are required when working within restricted approach boundary of exposed live parts that are not put into an electrically safe work condition or when the employee interacts with the equipment when it is not exposed, but a increased likelihood of injury from exposure to arc flash exists. 130.2(B)(3): Exception for testing, troubleshooting, voltage

measuring, thermography, visual inspection, access to or egress from the area or general housekeeping by QUALIFIED PERSONS

NFPA 70E ARTICLE 130

130.4: Approach Boundaries to Live Parts for Shock Protection Shock Protection Boundaries – Limited and Restricted Approach

Boundaries– Limited Boundary - The closest an unqualified person can get to an

exposed, energized circuit– Restricted Boundary - Only qualified persons are allowed inside this

boundary with proper PPE

APPROACH BOUNDARIES AC SYSTEMS

ARC FLASH RISK ASSESSMENT

130.5 ARC FLASH RISK ASSESSMENT Shall be performed and shall:1. Determine if an arc flash hazard exists. If one does, the

assessment shall determine appropriate safety-related work practices, arc flash boundary and appropriate PPE. (Table 130.7(C)(15)(A)(a))

2. Be updated when a major modification or renovation takes place. It shall be reviewed at least every 5 years.

3. Take into consideration the design of the OCPD, OCPD opening time and the condition of maintenance.

The results of the assessment shall be documented.

ARC FLASH RISK ASSESSMENT

130.5(B) - ARC FLASH BOUNDARY Distance from energized circuit where a worker could receive an

incurable burn (1.2 cal/sq. cm.) 130.5(C) – ARC FLASH PPE One of the following methods (but not both) shall be used for the

selection of PPE:1. Incident Energy Analysis Method (Arc Flash Study)2. Arc Flash PPE Categories Method (NFPA 70E Tables)

INCIDENT ENERGY ANALYSIS METHOD

1. Determine Energy Levels Short Circuit (SC) Study – Power Protective Device Coordination (PDC) Study – Time Arc Flash Hazard Analysis – Power X Time = Energy

2. Recommendations Made to Reduce Energy Levels

3. Determine Appropriate Protective Equipment

4. Other Benefits: One-lines, system health assessment, etc.

ARC FLASH PPE CATEGORIES METHOD

Table 130.7(C)(15)(A)(b) for AC systems Gives PPE categories for different equipment pieces Need to know available short circuit current, device clearing

times and working distances (How do you do this?) Table 130.7(C)(15)(B) for DC systems – similar to AC

systems Table 130.7(C)(16) for PPE Categories

ARC FLASH LABELS

Equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures and motor control centers shall be labeled with the following:1. Nominal system voltage2. Arc flash boundary3. At least one of the following:

a. Available incident energy / working distance or PPE category from NFPA 70E tables, but not both

b. Minimum arc rating of clothingc. Site-specific level of PPE

ARC FLASH LABELS - EXISTING

PPE – HARDHAT & FACESHIELD

Hardhats w/ faceshield 8 -12 Cal/cm2 Ultraviolet (UV) Infrared (IR) PROTECTION

ARC RATED CLOTHING

Coveralls (shown) Hooded Parkas Bib Overalls Lab Coats

ARC FLASH CLOTHING

INSULATED HAND TOOL REQUIREMENTS

All tools must be marked with the international safety symbol for 1000 Volts

All tools must state the rating of 1000V All tools must have the name of manufacturer All tool must have the year of manufacture All tools must have the part number or code number All of this information must be marked on every tool These must be used inside the limited approach boundary

GLOVES FOR ELECTRICAL WORK

FACE SHIELD, ARC SUIT, COOLING VEST

ARC FLASH ENERGY MITIGATION

Evaluate requirements Review circuit breaker settings to reduce incident energy Review fuse size and type to reduce incident energy Look at adding protective devices where necessary to reduce

incident energy

ARC FLASH ENERGY MITIGATION

Power Electronics VFD’s do not allow current to flow back into fault, thus reducing energy in

arc flash Cost savings in reduced energy and increased control

Add impedance: Add or change transformers

– Dual Purpose: harmonics mitigation– Dual Purpose: changing downstream load voltage– Cost-effective during design and in retrofit

Size cables closer to load– Often oversized for future loads– Dual Purpose: smaller wire = less cost– Only cost-effective during design