PPE Category Screen Calculator

The PPE Category Screen Calculator produces an entered rating margin by subtracting the entered incident energy record from the entered arc-rating record. It is used during electrical safety-document review to determine whether two recorded values are numerically comparable and to show the amount of arc-rating margin present in the selected energy unit.

\(\displaystyle \text{Entered Rating Margin} = \text{Entered Arc Rating} - \text{Entered Incident Energy}\)

The result supports review of arc-flash study records, equipment labels, PPE documentation, and source references. It does not calculate an arc-flash incident-energy value, establish an arc-flash boundary, select a PPE category, authorize energized work, or determine whether a specific garment is compliant.

Incident Energy and Arc Rating

Incident energy is the energy value entered from the reviewed record. Arc rating is the protective rating entered from the associated PPE or source record. For the comparison to have meaning, both values must use the same unit basis and originate from records that can reasonably be compared.

The calculator uses these fields:

Field	Electrical record purpose
Method and version	Identifies the study or evaluation method recorded with the values, such as study-method-v1.
Energy unit basis	Establishes the common basis for both records, such as cal/cm2.
Entered incident energy	Records the reviewed incident-energy value.
Entered arc rating	Records the reviewed arc-rating value.
Entered category record	Indicates whether a category value exists in the source material.
Source reference	Identifies the record being reviewed, such as record-ppe.

The worksheet requires method, unit, and source fields to be present before it performs the comparison. Those entries preserve traceability between the numerical result and the underlying electrical-safety record.

Rating Margin Calculation

The calculation is direct:

\(\displaystyle \text{Entered Rating Margin} = \text{Entered Arc Rating} - \text{Entered Incident Energy}\)

A positive margin means the entered arc-rating value is greater than the entered incident-energy value by the displayed amount. A zero margin means the two entered values are numerically equal. A negative margin means the entered arc-rating value is lower than the entered incident-energy value.

The calculation does not convert units. If incident energy is entered in cal/cm2, the arc rating must also be entered in cal/cm2. A comparison between different unit bases is not valid unless the source records have already been converted and documented outside this worksheet.

Calculation Example

Enter the following reviewed records:

Calculator field	Entered value
Method and version	study-method-v1
Energy unit basis	cal/cm2
Entered incident energy	4.2
Entered arc rating	8
Entered category record	Recorded
Source reference	record-ppe

The worksheet calculates:

\(\displaystyle 8 - 4.2 = 3.8\)

Entered rating margin: 3.8 entered unit

With cal/cm2 selected as the unit basis, the displayed result is a 3.8 cal/cm2 numerical difference between the entered arc-rating record and the entered incident-energy record.

The result screen should also show:

• Source note: Source recorded
• Record comparison: Entered values comparable
• Calculation basis: The worksheet subtracts entered incident energy from the entered arc-rating record after method, unit, and source fields are present.

Record Comparison Limits

The calculator is a record-comparison worksheet. It does not determine whether the entered incident-energy value is current for the equipment configuration, available fault current, protective-device settings, working distance, electrode configuration, or system operating condition.

It also does not verify the condition, labeling, layering, coverage, manufacturer instructions, garment arc rating, worker qualification, work permit requirements, or energized-work authorization. Those decisions require review of the applicable electrical-safety program, the original study documentation, equipment labeling, and the authority having jurisdiction where applicable.

A recorded PPE category is retained only as source-record information. The calculator does not output a PPE category or determine garment selection or compliance.