Electrical Safety

What percentage of electrical deaths in the workplace is caused by arc flash?

Approximately 50%.

What is the purpose of an Arc Flash Hazard Analysis?

To determine the risk of personal injury from arc flash which is possible in any sort of electrical system.

What is the Arc Flash Protection Boundary?

The distance for a specific level of incident energy used to determine the needed PPE.

What must a worker wear within the Flash Protection Boundary?

Proper PPE to avoid second-degree burns.

At what incident energy level must greater emphasis be placed on de-energizing equipment?

When incident energy exceeds 40 cal/cm2 (category 4)

What are the three approach boundaries for working near live electrical equipment?

• 3 approach boundaries:

  • Limited Approach:

    • only qualified persons, if unqualified - must be escorted.

  • Restricted Approach:

    • only qualified persons, requires use of shock protection techniques.

    • Documented work plan needed and PPE.

  • Prohibited Approach:

    • only qualified persons, requires use of shock protection techniques.

    • Specially written, approved, work plan needed and PPE.

What constitutes PPE in the context of arc flash safety?

PPE is a barrier between the wearer and the work environment and serves as the last line of defense. Arc flash PPE minimizes burn injury and provides extra seconds of protection.

What are the hazard/risk categories based on incident energy levels?

• Hazard/categories are rated from 0-4.

  • 0 = 4.5 oz/yd2

  • 1 = 4 cal/cm2

  • 2= 8 cal/cm2

  • 3= 25 cal/cm2

  • 4= 40 cal/cm2

  • Higher number is more dangerous

  • minimum arc blast is 4 cal/cm2 which is category 1 = FR apparel states cal/cm2 rating on it.

  • CSA Z462 outlines this PPE.

  • Realistically there are only 4 categories that specify ARC rated FR clothing.

What is required for an electrical safety program according to CSA Z462?

A five-step process that includes program procedures, engineering studies, safety training, PPE supplies, and maintenance.

• Step 1 - employer develops program procedures - living document

• Step 2 - electrical system engineering study by professionals - live equipment to be marked by a label containing:

  • available incident energy

  • min PPE arc rating

  • required PPE level

  • highest hazard/risk category

• Step 3 - conduct regularly scheduled safety training and audits

• Step 4 - ensure adequate PPE supplies

• Step 5 - maintenance of all electrical distribution system components

What should you not do with someone else's lockout lock?

You should not put your lock through another person’s lock. You should also not attempt to open it or cut it off.

What current level can lead to ventricular fibrillation of the heart?

100-200mA.

What should you maintain if the line voltage of a powerline is unknown?

A safe distance of 7 meters.

What is the first step in responding to an electrical accident?

Remove the victim from danger.

What does OSHA require regarding machinery before servicing?

• OSHA 39 general safety regulations require that machinery is locked out and tagged.

Amperage vs Effect chart

• 1mA = no sensation

• 1-8mA = shock sensation not painful

• 8-15mA = painful shock

• 15-20mA = painful shock with muscular contraction

• 20-75mA = painful shock with severe muscular contraction, hard to breathe

• 100-200mA = painful shock, ventricular fibrillation of heart. Often fatal.

• 200mA + = severe burns, stops heart, artificial respiration needed immediately.

• Current is what kills, voltage determines how much current will flow based on your body’s resistance.

• to facilitate multiple locks on a single switch or valve, _____ are used

• to facilitate multiple locks on a single switch or valve, “lockouts” are used (the common clasp where multiple people can place their lock)

Can you shut down a motor via the breaker?

• Do not open a breaker first before shutting down a motor (live load can create arc flash hazard).

What does each lock need when locking out?

• Each lock needs a tag including a warning to not operate, person’s name, signature, date lock was installed.