Safety & Protection calculator
Electrical Compliance Calculator
This electrical compliance calculator is intentionally narrow. Instead of pretending to certify an entire facility, it screens three common U.S. questions: whether equipment working space clears a basic NEC-style minimum, whether a measured single rod is above or below the familiar 25-ohm supplemental-electrode trigger, and whether key documentation items are present before field work around energized equipment.
Updated July 10, 2026
A 480 V panel in Condition 2 needs 42 in of depth, at least 30 in or the equipment width, and 78 in of working-space height.
Single-rod screen: 32 ohms > 25 ohms means a supplemental electrode should be expected unless the accepted field path says otherwise.
Choose working clearance, single-rod ground, or documentation readiness below for a narrow U.S. compliance screen
Example Calculations
How to Use
What this electrical compliance calculator actually checks
Use this page when the immediate question is a specific field screen, not a complete facility compliance decision. The calculator covers only three tasks:
- Working Clearance for common 0-600 V equipment using depth, width, and height checks.
- Single-Rod Ground Screen for the familiar 25-ohm supplemental-electrode trigger on one rod, pipe, or plate electrode.
- Documentation Readiness for one-line diagrams, lockout/tagout procedures, qualified-person training, and field labeling in a U.S. electrical-safety workflow.
1. Working-clearance screen
The working-clearance mode is meant for the common jobsite question: does this panel, switchboard, or similar equipment have enough clear space in front of it? The screen uses the familiar NEC 110.26 style logic for:
- Depth based on nominal voltage to ground and the selected condition.
- Width as the greater of 30 in or the equipment width.
- Height at a minimum of 78 in.
For 0-150 V to ground, the usual working depth is 36 in regardless of the condition. For 151-600 V, the familiar depth screen is 36 in for Condition 1, 42 in for Condition 2, and 48 in for Condition 3.
This is a narrow screen only. Dedicated-space, egress, door-swing, and equipment-specific listing requirements still need their own review.
2. Single-rod ground screen
The grounding mode does not calculate a whole grounding system. It only interprets a measured value for one rod, pipe, or plate electrode against the familiar 25-ohm trigger used in the NEC single-rod supplemental-electrode rule.
If the measured value is above 25 ohms, you should expect a supplemental electrode unless accepted field testing and the adopted code path say otherwise. If the measured value is 25 ohms or less, keep the field test record with the project documentation.
The important boundary is this: 25 ohms is not a universal grounding maximum for every building, service, substation, utility interconnection, or sensitive electronic installation. It is only the single-electrode trigger screened here.
3. Documentation-readiness screen
The documentation mode is a practical readiness check before work around electrical equipment. It asks whether the following are present and current for the selected scenario:
- current one-line documentation
- written lockout/tagout procedure
- qualified-person training currency
- arc-flash labeling when equipment is likely to be examined while energized
- documentation updates after a major system change
This part of the page is informed by the usual U.S. safety framework: OSHA work-practice rules, OSHA safeguards for personnel protection, lockout/tagout procedure control, and NFPA 70E field-label and program expectations. The result is a readiness score, not a legal finding.
What this page does not do
- It does not certify full NEC, OSHA, or NFPA 70E compliance for a facility.
- It does not replace an AHJ review, a formal electrical-safety program, or a project-specific punch list.
- It does not replace field measurement, accepted test procedures, or equipment-manufacturer instructions.
When to use other calculators instead
- Use the Grounding Resistance Calculator when the job is estimating rod resistance from soil resistivity and spacing before installation.
- Use the Circuit Breaker Sizing Calculator or Motor Branch Protection Calculator for overcurrent-device screening.
- Use the Arc Flash Calculator for simplified incident-energy review from a known study case.
- Use the Protection Coordination Calculator when the question is time-current separation between devices.
Common Applications
More applications. Open to review 2 additional use cases.
Frequently Asked Questions
Does this calculator certify a whole building or facility as code compliant?
No. It only screens three narrow checkpoints. Final acceptance still depends on the adopted code edition, AHJ interpretation, OSHA duties, NFPA 70E program documents, manufacturer instructions, and the actual field condition.
Is 25 ohms the required maximum for every grounding system?
No. The 25-ohm value screened here belongs only to the familiar single-rod supplemental-electrode trigger. Many grounding designs use different project targets, and some installations need a much broader grounding review than this page provides.
If my equipment is 40 in wide, is 30 in of width still enough?
No. This screen uses the familiar rule that working-space width is the greater of 30 in or the equipment width. A 40 in-wide enclosure needs at least 40 in of clear width in this basic review.
Why does the documentation mode ask about energized examination and arc-flash labels?
Because field labeling is tied to equipment that may be examined, adjusted, serviced, or maintained while energized. The calculator uses that question to decide whether the arc-flash label belongs in the readiness score for the selected situation.
Does a high readiness score replace safe-work planning?
No. A high score only means the selected documents appear to be present. Safe-work planning still depends on the task, the equipment, the employer safety program, and the actual field condition on the day of the work.
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