Everything you need to know about arc-flash hazard analyses

They can reach 35,000oF, which is four times as hot as the sun’s surface, and can be extremely hazardous to workers by generating:

• Explosions
• Fireballs
• Shockwaves
• Fragments of equipment
• Gas and temperatures of up to 225oC
• Molten metal projected at up to 1000 km/h
• Unbearable pressure and noise
• Intense light

Consequences to personnel can be disastrous, even fatal. Approximately 200 arc-flash incidents occur yearly in Canada. Employers in all provinces are required by law to take the necessary measures to protect the health, safety and physical integrity of their workers. An electrical hazard analysis helps employers meet health and safety requirements for personnel working on electrical installations. In fact, this analysis helps:

• identify potential risks
• assess incident energy levels at access points
• control hazards using the right personal protective equipment (PPE)
• inform personnel of and train them on the risks of exposure
• implement mitigation measures to minimize incident energy levels

Here we answer some of the questions most frequently asked about arc-flash hazard analyses.

1. Am I required to carry out an electrical hazard analysis under standard CSA Z462 knowing this standard is not legally binding?

You’re right, the CSA Z462 standard is not legally binding; however, it is considered the reference (generally accepted practice) for electrical safety in the workplace.

Since employers are legally required to ensure the safety of their employees, they must comply with this standard or demonstrate that they are providing a level of safety at least equal to that of the standard.

The CSA Z462 standard is therefore indirectly legally binding.

2. What equipment must I perform an electrical hazard analysis on?

An electrical hazard analysis (electric shocks and arc flashes) must be performed on all electrical conductors or other circuit parts operating at 50 V or more in work situations where electrical hazards might exist (zero energy).

(CSA Z462-15, sections 4.3.3, 4.3.4 and 4.3.5).

3. How long are arc-flash hazard analyses valid?

The analysis must be updated when a major modification or renovation takes place. It shall be reviewed periodically, at intervals not to exceed five years, to account for changes in the electrical distribution system that could affect the result of the analysis.

(CSA Z462-15, section 4.3.5 1.b)

4. What equipment must I identify?

All electrical equipment, such as switchboards, panelboards, industrial control panels, meter socket enclosures and motor control centres, that are installed in other than dwelling units and are likely to require examination, adjustment, servicing, or maintenance while energized, must be field marked to warn persons of potential electric shock and arc-flash hazards.

(CSA C22.1-15, section 2-306; CSA Z462-15, section 4.3.5.5)

5. Are there differences between the American NFPA 70E-15 standard and the Canadian CSA Z462-15 standard?

No. The CSA Z462-15 standard is based on the NFPA 70E-15 standard and is harmonized with the Canadian Electrical Code.

6. Do my DC installations require an electrical hazard analysis?

Yes, if the voltage rate is 50 V or more. The 2015 edition of the CSA Z462 standard provides for DC systems:

• Table 1B: approach boundaries for shock protection (section 4.3.4)
• A maximum power method for incident energy calculations (Appendix D.5.1).

7. Is low-voltage (600 V or fewer) work less hazardous than high-voltage work?

NO.

Rule of thumb: Incident energy (≈ x iarc, ≈ x 1/d²; ≈ x tarc)

• The arc current intensity is higher at low-voltage (double or more)
• Working distances are shorter for low-voltage: 0.46 m versus 3 m or more for high-voltage
• The exposure time is the same based on distribution levels

Additionally:

• Low-voltage work is more frequent
• There is less fear of low-voltage work, so workers are more reckless

Incident energy levels are frequently 40 cal/cm2 or more on low-voltage installations.