Applying NFPA 70E Principles in the Field

Infrared thermography is one of the most powerful predictive maintenance tools available. It allows thermographers to evaluate energized electrical assets under load without physical contact. However, the fact that equipment must remain energized introduces inherent electrical hazards — shock, arc flash, arc blast, and thermal energy exposure.

Safety is not a recommendation during a thermographic inspection. It is a procedural requirement.

This article outlines critical safety practices aligned with NFPA 70E – Standard for Electrical Safety in the Workplace, including proper PPE selection, approach boundaries, barricading practices, and disciplined field execution.

1. Understanding the Hazard Before Opening the Panel

Before a single fastener is removed, the thermographer must:

• Perform a documented risk assessment
• Review available arc flash labeling
• Identify:
  • Nominal system voltage
  • Available incident energy (cal/cm²)
  • Arc flash boundary
  • Shock protection boundaries
• Confirm equipment is in normal operating condition per NFPA 70E 110.4

If labeling is missing, outdated, or unreadable, the inspection should not proceed without further engineering evaluation.

2. Proper PPE for Thermographic Inspections

NFPA 70E requires PPE selection based on calculated incident energy or PPE category method. Thermographers must never rely on assumptions.

Required PPE May Include:

• Arc-rated clothing (rated equal to or above incident energy)
• Arc-rated face shield or hood
• Class-rated voltage gloves with leather protectors
• Hard hat (arc-rated where required)
• Safety glasses
• Hearing protection
• Leather footwear
• Balaclava (if face shield used without hood)

3. Approach Boundaries & Working Distance

NFPA 70E defines:

Shock Protection Boundaries

• Limited Approach Boundary
• Restricted Approach Boundary

Arc Flash Boundary

Distance at which incident energy equals 1.2 cal/cm².

Thermographers must:

• Remain outside restricted boundaries unless qualified and protected
• Avoid reaching across exposed conductors
• Maintain body positioning that limits torso exposure
• Keep non-essential personnel outside boundaries

Distance Guidelines

• Stand to the side when opening panels (never directly in front)
• Use insulated tools
• Maintain a stable stance
• Avoid leaning into enclosures

4. Barricading & Safety Tape

An energized inspection area must be controlled.

Best practices include:

• Establishing barricades at the arc flash boundary
• Using red/yellow safety tape to mark perimeter
• Posting warning signage
• Assigning an attendant when required

This prevents unqualified personnel from entering hazardous zones during inspection.

5. Procedural Discipline During Inspection

Thermographers should follow structured workflow:

1. Verify load conditions
2. Inspect for visible damage before removal
3. Stand to side when opening door
4. Secure door to prevent movement
5. Capture thermal and visual image
6. Minimize dwell time inside boundary
7. Re-secure all covers properly

Never:

• Remove internal dead fronts unless required and authorized
• Touch energized conductors
• Rely solely on thermal camera for safety assessment

6. Environmental Considerations

Electrical rooms and industrial mechanical spaces introduce added hazards:

• Steam lines
• Chemical exposure
• Wet floors
• Limited egress

Thermographers must evaluate:

• Slip/trip hazards
• Adequate lighting
• Ventilation
• Emergency access

7. The Professional Standard

Infrared thermography is non-contact — but it is not zero-risk.

Professional thermographers operate under:

• NFPA 70E compliance
• OSHA electrical safety requirements
• Documented procedures
• Continuous safety training

Safety is part of the deliverable.

A thermographic inspection that identifies overheating connections but ignores exposure risk is incomplete. The goal is twofold:

1. Identify failure points
2. Protect personnel

Both are non-negotiable.