Electrical safety is critical in any facility that deals with high-voltage systems. One of the most effective ways to protect workers from arc flash hazards is through the proper selection of Personal Protective Equipment (PPE). The NFPA 70E standard defines various levels of PPE based on incident energy exposure, measured in calories per square centimeter (cal/cm²). Understanding PPE suit ratings and calorie levels ensures compliance, reduces the risk of injuries, and enhances overall workplace safety.
This guide will walk you through arc flash suit ratings, PPE categories, and how to choose the right level of protection for your electrical work environment.
What Are Calories in Electrical PPE?
In electrical safety, a “calorie” refers to a unit of thermal energy. Specifically, it’s a measure of the incident energy a worker may be exposed to during an arc flash, and how much heat a garment can withstand without causing a second-degree burn.
The higher the cal/cm² rating of your PPE, the more protection it offers. For example:
- 4 cal/cm²: enough to cause a second-degree burn
- 8 cal/cm² and above: higher energy, greater risk
- 40+ cal/cm²: considered extremely dangerous—beyond the capabilities of most PPE
NFPA 70E 130.5(G) requires employers to determine incident energy exposure and provide suitable PPE.
NFPA 70E PPE Categories & Arc Ratings
NFPA 70E breaks PPE down into four categories, each based on the minimum arc rating required:
Category 1 (Minimum Arc Rating: 4 cal/cm²)
Required PPE:
- Arc-rated long-sleeve shirt and pants (or coverall) rated at least 4 cal/cm².
- Arc-rated face shield or arc flash suit hood.
- Safety glasses, hearing protection, and insulated gloves.
Category 2 (Minimum Arc Rating: 8 cal/cm²)
Required PPE:
- Arc-rated long-sleeve shirt and pants with a rating of 8 cal/cm² or higher.
- Arc-rated face shield with a balaclava (or arc flash suit hood).
- Rubber-insulating gloves and leather protectors.
Category 3 (Minimum Arc Rating: 25 cal/cm²)
Required PPE:
- Arc-rated flash suit jacket and pants rated at least 25 cal/cm².
- Arc-rated flash suit hood.
- Arc-rated gloves, safety glasses, and hearing protection.
Category 4 (Minimum Arc Rating: 40 cal/cm²)
Required PPE:
- Full arc flash suit including a jacket, pants, and hood with a rating of 40 cal/cm² or higher.
- Heavy-duty rubber-insulating gloves and leather protectors.
- Arc-rated face protection, hearing protection, and safety footwear.
These categories guide you in choosing the right combination of protective gear for each job.
Common Arc Flash Protective Equipment
When selecting PPE for arc flash protection, it’s important to understand the full range of gear required depending on the job’s hazard level. Below is a list of commonly used arc flash protective equipment, categorized by protection level:
Basic PPE (Category 1-2)
Arc-Rated Shirt and Pants – Flame-resistant fabric rated for 4 to 8 cal/cm²
Arc-Rated Face Shield – Includes chin cup and wrap-around visor for face protection
Rubber-Insulated Gloves – With leather protectors
Hard Hat with FR Cover – Protects head from impact and arc heat
Intermediate PPE (Category 3)
Arc-Rated Flash Suit Jacket and Bib Overalls – Rated 25 cal/cm² or higher
Arc Flash Hood – Covers entire head and face; often includes a built-in fan for ventilation
Dielectric Footwear – Provides insulation and protection against electrical hazards
Advanced PPE (Category 4)
40 cal/cm² Full Arc Flash Suit – Includes hood, gloves, coveralls, and boots
Arc Suppression Blanket – For additional protection in high-risk areas
Voltage-Rated Tools – Non-conductive tools designed for energized work
Arc Flash Suits
Head Protection
Face Protection
Hand Protection
Foot Protection
When Do You Need a Danger Label Instead of a Warning?
According to NFPA 70E Annex D and Table H.3(b), if the incident energy level exceeds 40 cal/cm², there is no available PPE proven to protect workers from the potential effects of an arc flash at that level. In these cases:
- Labels should use a “Danger” header instead of “Warning”
- Work must be justified and approved under an energized work permit
- Engineering controls or remote operation tools may be required
Avoiding Common Mistakes with PPE Calories
Here are some common pitfalls to avoid:
- Wearing a high-calorie suit when not required, leading to heat stress
- Assuming all arc-rated clothing provides equal protection
- Ignoring layering compatibility between garments
- Not updating PPE after system changes or reassessments
Maintaining PPE for Maximum Protection
Refer to NFPA 70E Annex H.4 for care and maintenance:
- Inspect PPE for damage or contamination before every use
- Follow proper laundering instructions—no bleach or harsh detergents
- Store in a clean, dry space away from UV light or chemicals
Well-maintained PPE lasts longer, performs better, and helps you stay in compliance.
At C&H Electric, we help businesses stay compliant and protected with expert guidance on arc flash safety, PPE selection, and NFPA 70E compliance. Whether you need assistance in conducting an Arc Flash Hazard Analysis or choosing the right PPE for your facility, we are here to help!
