Electrical Safety

Question 1

What is arc flash?

Answer 1

An electrical current that passes through air between ungrounded conductors or between ungrounded and grounded conductors that produces high temperatures.

Question 2

What are arc flash hazards?

Answer 2

Are dangerous conditions associated with the possibility or release of energy caused by an electrical arc.

Question 3

What are arc faults?

Answer 3

Are high power discharges of electrical energy that change into heat.

Question 4

Name three workplace hazards.

Answer 4

Shock and electrocution and in recent years also arc flash

Question 5

What laws have been developed to address the serious workplace hazards electricians are facing on the job?

Answer 5

The Canadian Standards Association (CSA) Z462: Workplace Electrical Safety Standard

Question 6

What are the objectives of the Workplace Electrical Safety Standard?

Answer 6

It stipulates requirements for identifying hazardous equipment and for development of safe work procedures around this equipment. It also gives guidance on selection of personal protective equipment.

Question 7

What is arc flash hazard analysis

Answer 7

Determination of the risk of personal injury as a result of exposure to incident energy from electrical arc flash.

Question 8

What is arc flash protection boundary

Answer 8

The distance for a specific level incident energy. Usually provided by the manufacturer.

Question 9

What is the risk for a person entering the flash protection boundary (FPB)

Answer 9

A person could receive second degree burn if an electric arc flash were to occur.

Question 10

Must special flash-flame protection equipment be worn from persons entering the flash protection region.

Answer 10

Yes

Question 11

What is incident energy exposure?

Answer 11

The amount of thermal incident energy to which a worker’s face and chest could be exposed at working distance during an electrical arch event.

Question 12

What are the measuring units for incident energy exposure?

Answer 12

Calories per centimeter squared (cal/cm2)

Question 13

How does does arching fault current occur?

Answer 13

Arching fault current results from a short circuit or electrical contact between two conductors at different potentials in which the impedance or resistance between the conductors is essentially zero.

Question 14

What is arc duration?

Answer 14

Arc duration is the total time it takes for the system protective device to detect and interrupt a fault current.

Question 15

What is a qualified person?

Answer 15

Is one who has the skills and knowledge related to the construction and operation of the electrical equipment and installations and has received sufficient training to recognize and avoid the hazards involved.

Question 16

What is limited approach boundary?

Answer 16

Is a shock protection boundary to be crossed only by a qualified person.

Question 17

Can an unqualified person cross the limited approach boundary?

Answer 17

Yes, an unqualified person can cross the limited approach boundary, only if he is escorted by a qualified person.

Question 18

What is a restricted approach boundary?

Answer 18

Is a shock protection boundary that requires:

1. qualified person
2. use of shock protection techniques and equipment when crossed
3. qualified person crossing must have a work plan, approved by authorized management.
4. Use PPEs that are rated for the voltage and energy level involved.

Question 19

What is prohibited approach boundary?

Answer 19

Due to the proximity to the shock hazard crossing this boundary requires:

1. qualified person who has completed required training
2. must wear appropriate PPE
3. must have written approved plan
4. plan the work to keep all parts of the body out of the prohibited space.
5. the tools used in the prohibited space must be rated for direct contact at the voltage and energy level involved.

Question 20

How many hazard/risk categories levels of electrical task there are?

Answer 20

There are five levels of hazard/risk categories.

Question 21

How are the hazard/risk categories numbered?

Answer 21

From 0 to 4 based on the severity of the arc fault risk

Question 22

Hazard/Risk Categories correspond to what levels of PPE Arc Rating (cal/cm2)

Answer 22

HRC 0 - non melting, flammable materials
HRC 1 - 4   cal/cm2 rated FR clothing
HRC2 - 8   cal/cm2 rated FR clothing
HRC3 - 25 cal/cm2 rated FR clothing
HRC4 - 40 cal/cm2 rated FR clothing