Engineering & design
Electrical Engineering and Design
In-house design for commercial projects across Maricopa County, with a licensed Arizona professional engineer sealing the drawings that have to be sealed.
Most of the electrical engineering on a commercial job is not the part that needs a seal. Load calculations, the one-line, feeder sizing, panel schedules, photometrics and the utility application package are production work, and we do that in-house. What needs a seal gets one, from a licensed Arizona PE we coordinate. This page says where the line falls.
What we draw, and what the PE seals
Arizona registers professional engineers through the Board of Technical Registration, and contractor licensing is no substitute for it. We do not hold a PE seal in-house. Where a set has to be signed and sealed we coordinate a registered Arizona PE, hand over the calculations and the model, and let them review, revise and take professional responsibility for it.
| Deliverable | Produced by | Sealed? |
|---|---|---|
| Connected and demand load study | Our design team | No — an input to the set |
| One-line, equipment schedule, feeder and conduit sizing | Our design team | Yes, where the AHJ or spec requires it |
| Available fault current and interrupting rating | Our design team, from utility data | Yes, where issued as a study |
| Panel schedules, circuiting, voltage drop | Our design team | Rides on the sealed set |
| Photometric model and point-by-point grid | Our design team, from IES files | Rarely; reviewed through zoning |
| Utility application and service entrance drawings | Our design team | No — a utility review |
| Signed and sealed permit drawings | Licensed Arizona PE we coordinate | Yes |
Our licenses are listed with their numbers on the credentials page; design and construction under one contract is design-build.
The load study and the one-line decide your gear order
The expensive decision gets made in the first fortnight, on the one-line. Service size, voltage, bus ampacity and interrupting rating all fall out of the load study and the available fault current, and all four lock the day the switchgear is released for manufacture. Change one afterwards and you are not revising a drawing, you are re-entering a lead time.
- Connected and demand load by panel and by feeder, with mechanical taken off the real equipment schedule rather than watts per square foot.
- Available fault current at the service and at each downstream board. Interrupting rating is a price and a lead time, not a checkbox.
- Voltage drop on the long runs, and service size against the utility's own limits.
Phoenix expects this in writing: plans submitted under the city's Annual Facilities Program must carry a one-line diagram, load calculations and fault current calculations per the Phoenix Building Construction Code. The utility limits sit outside the NEC — APS caps a non-residential single-phase 120/240 V service entrance at 800 amps (ESRM 201.1).
The one-line is a procurement document. Every APS commercial meter enclosure must be submitted to APS for approval before the equipment is manufactured, showing bus bracing (AIC rating), ampacity, dimensions, voltage, phase, service disconnect count and EUSERC page references. Get it wrong and the gear is rejected at submittal or rebuilt after it lands.
Panel schedules built for a 110-degree ambient
A schedule that passes in San Diego can fail here on ampacity alone. ASHRAE's cooling design condition for Phoenix is roughly 110°F dry bulb, and the informational note under NEC 310.15(B) points at the ASHRAE Handbook as the source for site ambient — so 110°F is defensible rather than folklore. Table 310.16 assumes 30°C (86°F): at 41–45°C a 90°C conductor keeps 87 percent of its table ampacity, and at 46–50°C it keeps 82. The wire ampacity calculator shows what that does to a feeder.
Rooftop is worse, and the rule gets misquoted constantly. It was not deleted in 2017. NEC 310.15(B)(2) in the 2020 and 2023 editions still adds 33°C (60°F) where a raceway or cable sits in direct sunlight less than 7/8 inch above the roof — with an exception worth real money, since Type XHHW-2 is not subject to it. NEC 310.10(D) separately requires conductors in direct sun to be sunlight resistant.
- A wire-type equipment grounding conductor is required in Phoenix, unincorporated Maricopa County and Glendale, all three amending NEC 250.118(4) so EMT alone does not qualify. This is the fastest way an out-of-state design earns a correction notice.
- NM cable is amended out of commercial buildings in Phoenix and Glendale, which strike the Type III, IV and V language from NEC 334.10.
Which NEC edition? Arizona has no statewide building or electrical code — cities and counties adopt independently under A.R.S. §9-801 and §11-861, so two jobs three miles apart can sit on different cycles. Phoenix has been on the 2023 NEC since 1 August 2025 under Ordinance G-7397, and Mesa, Chandler and Glendale are on it too. Scottsdale is on the 2020 NEC. Unincorporated Maricopa County is still on the 2017 NEC. For Gilbert, Peoria and Tempe we confirm the adoption with that city's building department before design starts.
Photometrics and outdoor lighting review
A photometric is a model, not a rendering. We build it from the manufacturer's IES files for the exact fixture and optic, at the mounting height and tilt the site will actually get, with a light loss factor that reflects dust and lumen depreciation. The deliverable is a point-by-point grid with average, minimum and average-to-minimum uniformity, plus the property-line values a reviewer checks first.
Outdoor lighting is a zoning matter here, not an electrical one, and the rules change at the city line. Maricopa County's outdoor light control provisions (Zoning Ordinance Chapter 11, Section 1112) work on shielding and lamp type, with no lumens-per-acre cap and no color-temperature ceiling. Phoenix uses Zoning Ordinance Section 704, and Scottsdale routes every exterior lighting design through Development Review Board approval. If your last site lighting job was in Tucson, unlearn it — Tucson and Pima County cap light output per acre and color temperature at 3,500 K, and no Maricopa County jurisdiction we work in does either.
Controls scope is a jurisdiction question too. Phoenix deleted three sections of the 2024 IECC outright — C405.12 automatic receptacle control, C405.13 energy monitoring, and C405.15, which would have required on-site renewable generation of at least 0.75 W per square foot — and made Section C408 commissioning optional. Maricopa County adopted its energy code as voluntary. Same fixture package, different scope, different price.
Service coordination with APS and SRP
Open the utility file first, not last. Neither utility publishes a committed lead time for commercial new service — APS says only that timelines vary with complexity and current turnaround — so the only schedule protection available is starting early.
- The utility engineers its system to your meter panel, reviews the service entrance drawings, stakes and inspects trench, conduit and pads, sets the transformer and energizes. APS ESRM 200.1 lists the eight items needed to open the file.
- We obtain the permits, cut the trench to the utility's design, install conduit, pour the transformer pad and set the service entrance section. On an SRP job the pad, ground rod, conduit and backfill are customer-furnished.
- Nobody else energizes anything. Only authorized APS employees may energize an APS service, and SRP will not energize the load side until the AHJ has approved the installation.
Two hundred amps is the number to remember on both systems. APS requires EUSERC-approved CT-rated meter enclosures on every commercial service above 200 A, with test block or bypass provisions at 200 A and below (ESRM 302.9). SRP's accepted meter socket ratings are 100 A, 200 A and 400 A Class 320, and the 400 A socket is residential only — so commercial above 200 A is CT-rated there too. Working clearances belong on the site plan early, not after the civil drawings are approved.
Both standards move. SRP republished its Electric Service Specifications on 30 April 2026 and logged six further changes by 11 August 2026, one of which eliminated Customer-Owned Service after 6 July 2026. Its own sections disagree on the shop-drawing threshold — 225 amps in Section 1, 400 amps in Section 9 — so we submit at the lower number.
Permit sets, plan review and what it costs
Phoenix commercial plan review and inspections run through SHAPE PHX, which took on commercial work on 27 April 2026. The city publishes actual turnaround rather than promises, and the July 2026 report is worth reading: major projects averaged 30 days for first review against a 45-day goal, medium 33 against 35, and minor — under 5,000 sq ft or under $350,000 — 33 days against a 25-day goal. Small commercial is currently the slowest tier in Phoenix.
Budget the review, not just the permit. The Phoenix commercial plan review fee is 80 percent of the permit fee where valuation exceeds $50,000, expedited initial review is three times that, and a deferred submittal carries a $390 intake fee, all under the schedule effective 20 January 2026.
Self-certification can produce a permit in one to five business days, but it is commonly misdescribed. The disciplines that may self-certify in Phoenix are architects, structural engineers, civil engineers and landscape architects; electrical engineers participate as peer reviewers and cannot self-certify your electrical drawings. Either way, A.R.S. §9-835 limits a municipality to one comprehensive written correction request.
Design is a deliverable you can buy on its own. We sell design to anyone who needs a set drawn, whether or not we ever touch the installation — electrical contractors self-performing the work, general contractors and construction managers, owners and developers taking it out to bid, architects and engineering teams subbing out the electrical scope. What we do not do is hold a PE seal in-house: we produce the set and a registered Arizona professional engineer reviews it, revises what needs revising and seals it. We tell you which parts are ours and which are theirs before the contract is signed, not after.
Frequently asked questions
Do you produce stamped drawings?
We produce the drawing set and a licensed Arizona professional engineer seals it. We do not hold a PE seal in-house and we do not claim one. Our design team develops the load study, the one-line, the panel schedules, the photometrics and the permit set, and where the jurisdiction or the specification requires signed and sealed drawings we coordinate a registered Arizona PE who reviews the work, revises what needs revising and takes professional responsibility for the seal. We tell you which parts are ours and which are theirs before the contract is signed, not after.
Which NEC edition will my project be designed to?
Whichever edition the jurisdiction has adopted, which in the Valley is not one answer. Arizona has no statewide building or electrical code; cities and counties adopt independently. Phoenix has been on the 2023 National Electrical Code since 1 August 2025. Mesa, Chandler and Glendale are also on the 2023 NEC. Scottsdale is on the 2020 NEC. Unincorporated Maricopa County is still on the 2017 NEC. For Gilbert, Peoria and Tempe we confirm the current adoption directly with that city's building department before design starts rather than assume an edition.
When should utility coordination with APS or SRP start?
The same week the design starts. Neither utility publishes a committed lead time for commercial new service, and APS states only that project timelines vary with job complexity and current turnaround. To open the file APS wants the official street address and legal description, the structure type and square footage, the estimated load, the voltage and phase you want, and site plans showing the desired meter location. The utility then engineers its system up to your meter panel from that information. Every week the application sits unopened is a week added to the end of the job.
How long does Phoenix commercial plan review actually take?
The city publishes real numbers rather than promises. In its July 2026 turnaround report, major commercial projects averaged 30 calendar days for first review against a 45-day goal, medium projects averaged 33 days against a 35-day goal, and minor projects averaged 33 days against a 25-day goal. The counterintuitive part is that minor projects, meaning under 5,000 square feet or under $350,000, are currently running about eight days past goal and slower than major projects. Plan a small tenant improvement on the same review assumption as a large one.
Can you do design-only work and let another contractor build it?
Yes. Design is a deliverable we sell on its own, to anyone who needs a set drawn — another electrical contractor, a general contractor, an owner or developer taking the install out to bid, an architect or engineering team subbing out the electrical scope, or a client who simply wants a permit-ready set in hand. We do not require that we build it. The set is produced exactly as it is on our design-build jobs: we develop the load study, the one-line, the panel schedules, the photometrics and the permit set, and a registered Arizona professional engineer reviews it, revises what needs revising and seals it. Whether the design fee credits against construction if we are later awarded the install is handled job by job, so ask at proposal time.
Do you handle arc flash and protective device coordination studies?
Short-circuit and available fault current work is part of every design we produce, because the interrupting rating of the gear depends on it and that rating is both a price and a lead time. Full protective device coordination and arc flash incident-energy studies are a separate deliverable, and where they are issued as an engineering study they are sealed by the PE we coordinate rather than published under a contractor's name. Tell us at bid time whether the specification calls for a study, a label set, or both, because they price differently.
What is in a photometric package?
A point-by-point illuminance grid built from the manufacturer's IES files for the specific fixture and optic, at the real mounting height and tilt, with a light loss factor that accounts for dust and lumen depreciation rather than a factory-fresh number. It reports average, minimum and average-to-minimum uniformity across the paved area, and the values at the property lines, which is what a zoning reviewer checks first. We also flag the local shielding rule the design has to satisfy, because outdoor lighting in Maricopa County is governed by zoning ordinances rather than the electrical code, and those ordinances differ city by city.
Get a price on this scope
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Send us the plans, the scope, or just the problem. We will tell you what it takes. Call (602) 396-5216 or request a bid online.