Common Electrical Plan Check Issues

Electrical drawing sets carry a specific set of recurring compliance issues, many of them tied directly to National Electrical Code requirements around clearance, protection coordination, and documentation consistency. Here are the ones that show up most often in plan check comments.

Panel Schedule and One-Line Diagram Mismatches

A panel schedule that doesn't match the single line diagram, different breaker sizes, different circuit counts, different load totals, is one of the most common electrical plan check comments. This usually happens when one document gets revised late in the process without the other being updated to match. Structured AI's SLD-1 SLD vs Schedule Comparison check and MAC-2 SLD and Schedule Cross-Reference check are built specifically to catch this kind of drift between documents that are supposed to describe the same system.

Working Space and Clearance Violations

NEC 110.26 working space requirements around electrical equipment are frequently violated on drawings, sometimes because equipment gets relocated late in design without rechecking the required clearance envelope, sometimes because an architectural element, a wall, a column, a piece of casework, gets added without accounting for the electrical room's clearance needs. This is exactly what NEC-7 110.26 Working Space Check and MAC-1 NEC Working Space and Equipment Clearance are built to catch.

Panel Overloading and Missing Circuit Protection

Panel schedules showing spare capacity that's actually overloaded once all connected loads are totaled, or circuits missing required GFCI protection, are both common and both potentially dangerous if they make it through to construction. DEMO-1 Panel Schedule Spare Overloading and DEMO-2 Missing GFCI Protection are checks aimed directly at these two failure modes.

Voltage and Equipment Cross-Reference Errors

Equipment shown on one sheet powered at a different voltage than what's specified on the equipment schedule, or than what the actual nameplate rating requires, is a surprisingly common and easy to miss error, especially on larger sets with many pieces of equipment across multiple sheets. ELEC-1 Equipment Powered with Correct Voltage and ELEC-2 Equipment Voltage Cross-Reference check for exactly this kind of mismatch.

Conductor Sizing and Protection Coordination

Breaker-to-wire coordination errors, where a circuit breaker's rating doesn't properly protect the conductor it's feeding, are a life-safety issue as much as a code compliance one. NEC-5 240.4 Breaker-to-Wire Coordination and NEC-2 240 Conductor Protection Adequacy check for this directly, while NEC-3 215 Feeder and Transformer Secondary Conductor Sizing checks feeder and transformer-specific sizing requirements.

Motor Circuit and Arc Flash Considerations

Motor branch circuits have their own specific conductor sizing rules under NEC 430.22, checked by NEC-6, and larger electrical systems increasingly need arc energy reduction provisions under NEC 240.87, checked by NEC-1. Both of these are easy to miss on a quick review since they apply to specific equipment types rather than the electrical system broadly.

Why These Errors Are Easy to Miss Manually

Most of these issues require cross-referencing multiple sheets, a panel schedule against a one-line diagram, an equipment schedule against a floor plan, a breaker rating against a conductor size shown elsewhere. That cross-referencing is exactly the kind of systematic, multi-sheet checking that's tedious to do reliably by hand across a large set, and where automated checks tend to add the most value over manual review.

FAQ

Are these issues specific to commercial projects, or do they show up in residential work too? Panel schedule mismatches and circuit protection issues show up across project types, though the specific code sections and complexity, particularly around working space and SCCR verification, are more common on commercial and industrial projects with larger electrical systems.

Does catching these issues require a full electrical model, or can it be done from 2D drawings? These checks work against 2D drawing sets, panel schedules, one-line diagrams, and floor plans, without requiring a fully coordinated 3D electrical model.

What's SCCR and why does it matter? Short circuit current rating verification, checked by NEC-8 110.9 SCCR Verification, confirms electrical equipment is rated to safely interrupt the maximum available fault current at its location, a life-safety consideration that's easy to overlook without a systematic check.