Plan Review of a Mixed-Use Addition: Which Code Edition Governs?
A designer submits plans for a two-story addition to an existing mercantile building. The jurisdiction adopted a new edition of the electrical code effective January 1, and the plans were signed and sealed by the engineer on December 20 of the prior year but submitted for permit on February 3. The plans cite the previous edition throughout, including conductor ampacity tables and GFCI requirements for the new kitchenette. The plan reviewer also notices the existing service is a 400 A, 208Y/120 V, 3-phase system, and the addition adds a 60 A feeder to a rooftop packaged unit plus a 40 A feeder to a new subpanel. The reviewer's checklist requires verification of the applicable code edition, load calculation adequacy, and whether the existing service can support the addition.
1. How should the reviewer determine which code edition applies, and what should the reviewer do about the edition mismatch on the plans?
Read the worked answer
The controlling question is the jurisdiction's adoption ordinance, not the seal date. Most jurisdictions apply the code in effect on the date the permit application is accepted (or a specific 'grandfathering' window defined in the ordinance). The reviewer should:
- Read the local adoption/administrative ordinance to find the trigger date (application date, issuance date, or a stated transition rule).
- If the new edition applies, return the plans for revision to the current edition rather than approving under the superseded edition.
- If the ordinance allows plans prepared before the effective date to be reviewed under the prior edition, document that determination in the review record with a citation to the ordinance section.
The engineer's seal date is evidence but not the legal trigger. The reviewer must not simply accept the designer's cited edition.
2. The reviewer must judge whether the existing 400 A service can carry the addition. What information is needed, and what is the reviewer's proper action if the submitted load calculation is incomplete?
Read the worked answer
The reviewer needs a complete load calculation for the existing building plus the new loads, using the applicable demand factors and the correct method (standard or optional) consistently. Key inputs:
- Existing connected loads and demonstrated demand (utility billing data or prior approved calculations).
- New loads: the 60 A rooftop unit (continuous vs. noncontinuous, motor vs. HVAC), the 40 A subpanel with its calculated load, and any lighting/receptacle additions in the kitchenette.
- Whether the 400 A service has spare capacity after the calculated demand, and whether the service equipment rating and busbar are adequate.
If the calculation is incomplete or uses inconsistent methods, the reviewer should not guess. Issue a review comment requiring a complete, method-consistent calculation with the demand factors identified, and withhold approval until it is provided. The reviewer's job is to verify the method and inputs, not to substitute an estimate.