PPE category — and when the table cannot help you.
Two methods exist. You pick one per task and you do not mix them. This tool works the table method and, just as importantly, tells you when the table method does not apply to what you are looking at.
§ Which method are you using?
| Incident energy analysis method | Arc flash PPE category method | |
|---|---|---|
| Input | An engineering study — cal/cm² at a working distance | Equipment type, voltage, available fault current, clearing time |
| Output | A number. Select PPE from Table 130.5(G) | A category, 1 through 4. Select PPE from Table 130.7(C)(15)(c) |
| Use it when | You have a study, and the label carries an incident energy value | You have no study and your equipment falls inside the table parameters |
| Do not | Use the study number to pick a category, then dress to the category | Use the table when your fault current or clearing time exceeds the stated parameters |
§ Table method walker
§ What the categories mean
| Category | Minimum arc rating | Practical meaning |
|---|---|---|
| 1 | 4 cal/cm² | AR shirt and pants, face shield, hard hat, safety glasses, hearing protection, leather gloves |
| 2 | 8 cal/cm² | Adds a balaclava or hood — the face and neck coverage is the difference |
| 3 | 25 cal/cm² | Arc flash suit and hood. This is a two-person job in practice, and now formally so under 130.2(A)(2) if a permit is required |
| 4 | 40 cal/cm² | Full suit and hood. Above 40 cal/cm², the standard's guidance is that no PPE is a substitute for de-energizing |
§ If you have a study — Table 130.5(G)
Where the label carries an incident energy value, you do not use categories at all. Table 130.5(G) has two bands:
| Incident energy at the working distance | Required PPE |
|---|---|
| 1.2 – 12 cal/cm² | AR clothing with an arc rating ≥ the estimated incident energy; AR long-sleeve shirt and pants, coverall or arc flash suit (SR); AR face shield + balaclava, or arc flash suit hood (SR); AR outerwear as needed; heavy-duty leather, AR or rubber insulating gloves with protectors (SR); hard hat; safety glasses or goggles (SR); hearing protection; leather footwear |
| Greater than 12 cal/cm² | AR clothing with an arc rating ≥ the estimated incident energy; AR shirt and pants, coverall or arc flash suit (SR); arc flash suit hood — no face-shield option; AR outerwear as needed; AR gloves or rubber insulating gloves with protectors (SR) — leather-only gloves are no longer permitted; hard hat; safety glasses or goggles (SR); hearing protection; leather footwear |
SR = selection of one in the group is required. AN = as needed. The practical difference between the bands is the hood and the gloves: above 12 cal/cm² a face shield and balaclava will not do, and plain leather gloves will not do.
§ When the table method fails
- Available fault current exceeds the table parameter. Common on gear close to a large utility transformer — exactly where data centers are.
- Clearing time exceeds the table parameter. The most-missed condition, because clearing time depends on maintenance. See Chapter 2.
- Working distance differs from the table assumption.
- Equipment class not in the table — busway tap boxes, some rack PDUs and non-standard assemblies.
Reading a cal/cm² value off a label and then dressing to the "matching" category is a method error. The two methods use different assumptions. Use the number with Table 130.5(G), or use the equipment class with the category tables. Not both.
Judgment on the hard cases
The 16-hour class covers incident energy methods, the table limits, and how to challenge a label you no longer trust.
See the 16-hour class Bring it onsite