Switchgear and service entrance
Service, Switchgear & Distribution Equipment
Service entrances, switchboards and distribution gear in APS and SRP territory, coordinated with the serving utility from the first load sheet.
On a commercial job the service entrance is rarely the hardest thing to install. It is the hardest thing to schedule. The switchboard is a long-lead item, the serving utility has to approve the enclosure before it is built, and nobody can energize it except the utility. Get that order wrong and the gear shows up correct, on time, and unusable.
The submittal comes before the purchase order
Two facts drive most of what follows. First, at APS every commercial meter enclosure must be submitted through an APS representative for review and approval before the equipment is manufactured — ESRM 302.9. Not before installation. Before the factory builds it. Second, at both APS and SRP a commercial service above 200 amps is CT-metered, which changes the enclosure, the cabinet, the wiring and the price.
That rule quietly kills schedules. The GC releases the switchboard off an approved drawing set, the factory quotes a long lead, and nobody sends the one-line to the utility until the gear is in the yard. By then the meter section either matches the utility's standard or it does not, and field labor does not fix the second case.
APS 302.9 is specific about what the submittal has to carry:
- Engineering and manufacturer one-lines showing the neutral-to-ground bond link and the neutral disconnecting means
- Switchboard manufacturer, and the applicable EUSERC page references
- Ampacity, physical dimensions, voltage and phase
- Bus bracing — the AIC rating
- Number of service disconnects, all with padlockable provisions
- The accurate street address, on the drawings themselves
Any provision for a generator or an inverter is a second application. ESRM 302.9 requires a separate APS review where the equipment includes connections or provisions for any existing or proposed inverters or generators. Solar, storage and standby have to be settled before the switchboard is released, not after.
APS also publishes pre-approved lists — a Commercial Pre-Approved Equipment List for self-contained panels to 200 A, and a CT-Rated Pre-Approved Panelboard List. Buying off those lists is the short road.
APS: the ESRM, EUSERC and the 200-amp line
APS's governing document is the Electric Service Requirements Manual, current edition May 2026, published at aps.com/esrm in fourteen sections numbered 100 to 1400. It cancels and supersedes all previous APS specifications, conforms to EUSERC guidance, and warns that it is revised frequently and the online version governs. The page-level dates prove it: one page in Section 300 carries a 09/02/2026 revision while others in the same section still read 01/27/2022.
ESRM 302.9 sets the metering threshold. Commercial sites need EUSERC-approved test blocks and bypass provisions on self-contained services 200 amps and below, and EUSERC-approved CT-rated enclosures above 200 amps. EUSERC is the Electric Utility Service Equipment Requirements Committee, a western-utility standardization body both utilities work from — which is why the same EUSERC drawing numbers appear on submittals to either one.
| Item | ESRM | What it means on your job |
|---|---|---|
| Self-contained metering, 200 A and below | 302.9 | EUSERC-approved test block and bypass provisions in the meter enclosure. |
| Commercial, above 200 A | 302.9 | EUSERC-approved CT-rated meter enclosure. There is no self-contained option. |
| Every commercial meter enclosure | 302.9 | Submitted through an APS rep and approved before the equipment is manufactured. |
| Working space at the meter | 301.6, 301.7 | Three feet clear and continuously unobstructed from the face of the meter panel, wide enough for ready access, and three feet to any property line, sidewalk, alley or driveway. |
| Meter location | 301.6 | Thirteen location types are excluded outright, including inside a building without an acceptable meter room, restrooms, basements and depressed areas, hazardous locations, elevated areas, and surfaces subject to excessive vibration. |
| Single-phase 120/240 V, non-residential | 201.1 | Capped at an 800 A service entrance. Above that, with three-phase not readily available, two or more 800 A sections within ten feet of each other; APS provides the totalized metering at no cost while you provide the metering conduits and instrument cabinets. |
| Service entrance inspection | Front section | An APS inspection on top of the AHJ inspection. Call once as soon as the gear is on site and again the moment the inspector's corrections are complete. |
| Energization | 200.2-1 | Only authorized APS employees energize a service, and only on receipt of the city or county clearance. |
Applications run through the APS Construction Project Portal at build.aps.com. ESRM 200.1 lists the eight items an application must carry; ESRM 200.2-1 sets out a twenty-two step sequence that makes the division of labor explicit. APS engineers the system to your meter panel, reviews the service entrance drawings, stakes the trench and equipment locations, inspects trench, conduit and pads, schedules its crews and sets the meter. You obtain permits and easements, dig to the APS design, and furnish conduit and pads.
APS publishes no committed lead time for commercial new service — only that timelines vary by complexity and current turnaround. We will not invent a week count APS has not published. What we can do is get the application and the enclosure submittal in at design stage, which is the part of that clock a project team controls.
SRP: the ESS, and the end of Customer-Owned Service
SRP's counterpart is the Electric Service Specifications, republished 30 April 2026, in eleven sections plus an appendix of pre-approved service entrance sections. It moves faster than the APS manual: the revision log shows six standard changes between 30 April and 11 August 2026. One matters more than the rest.
SRP no longer permits Customer-Owned Service after 07/06/2026 (ESS Section 3, SES–Underground, Note 6). Existing conductors may be retained for maintenance, modifications, like-for-like replacements and right-sized installations. Where they are, the point of delivery stays at the transformer secondary bushings, the customer owns and maintains the cable, SRP installs connectors only where it is 750 MCM aluminum or copper, and an SRP representative must be present. If your standard detail is a customer-owned secondary run, it no longer exists on new work.
SRP's threshold lands in the same place by a different route. ESS Section 9 accepts meter sockets rated 100 A, 200 A and 400 A (Class 320) — and the 400 A socket is residential only, 320 A maximum. So commercial above 200 amps is CT-rated here too. SRP also requires safety test blocks on all non-residential services rated 200 amps or less, with a short exception list.
Shop drawings go by email to shopdraw@srpnet.com. There is a real discrepancy inside SRP's own document: Section 1 calls for shop drawings on all panels greater than 225 amps that are not pre-approved, while the Section 9 switchboard notes ask for service entrance sections 400 amps or larger. We submit at the lower 225 A threshold and confirm with SRP Distribution Design.
SRP will not energize the load side until the AHJ has approved the installation: Maricopa County and most cities in SRP territory have ordinances restricting it. Where no jurisdictional authority exists, SRP takes a Certificate In-Lieu of Electrical Clearance carrying the contractor's license number.
Who trenches, who pours, who sets the transformer
This is the part that gets mis-bid. Both utilities push the civil work onto the customer and keep the energized work for themselves.
| Scope | APS | SRP |
|---|---|---|
| Trench and backfill | Customer, to the APS design. APS specifies and stakes the trench and equipment locations and inspects the trench (ESRM 200.2-1). Contact a qualified APS rep before trenching, and Arizona 811 at least three days before excavating. | Customer does all trenching, backfill, boring and conduit, or pays a contribution for SRP to do it (Rules 4.6.2 and 4.6.3(b)). Trench and conduit are inspected before backfill. |
| Service conduit | Customer installs conduit from the service entrance equipment to the transformer pad or junction box (ESRM Section 500). | Customer installs conduit from the approved point of delivery to the SES and maintains it until SRP pulls conductors (ESS Section 3, Note 2). |
| Transformer pad | Customer provides the equipment pads; APS inspects conduit and pads before construction proceeds. | Customer provides and installs the pad, secondary window cover plate, ground rod, conduit and backfill (ESS Section 7). |
| Transformer and primary cable | APS | SRP |
| Meter enclosure, CT cabinet, test block perches, landing lugs | Customer buys and installs, from an approved submittal. | Customer furnishes, installs and maintains (ESS Section 9). |
| Instrument transformers, test switches, billing meter, seals | APS owns the meter and furnishes the instrument transformers and test switches. | SRP owns, furnishes, installs and maintains them, plus the secondary wiring from the instrument transformer to the meter socket and all final connections. |
| Drilling a switchboard for the meter | Per the approved enclosure submittal. | Customer does all the drilling before SRP mounts its meters; SRP provides the template (Rules 5.6.7). |
| Energizing | Authorized APS employees only. | SRP only, after AHJ clearance or a Certificate In-Lieu. |
SRP's pad detail in ESS Section 7 is worth reading before you price a pad. Three-phase pads are pre-cast, sized on the SRP design. A 5/8 inch by 8 foot copper-clad ground rod goes in the high-voltage opening, top 2 inches above the pad. Conduits stub 2 inches above the final pad surface with temporary plugs — not duct tape. Over thirteen conduits and a pull box is required under the secondary window. Backfill is CLSM per MAG Section 728, subgrade is approved by the SRP inspector before the pad is placed, and top of pad sits at least 4 inches above grade.
Then there is the clearance nobody leaves room for on the site plan. SRP requires 12 feet of clear working space at the front of a pad-mounted transformer, 3 feet at the sides and 18 inches at the back. A landscape island or a parking stall inside that 12 feet becomes a redesign after the pad is poured.
What the utility charges, and whether you get it back
The biggest difference between an APS job and an SRP job is not technical. It is who wrote the money rules. APS is regulated by the Arizona Corporation Commission and its line extension terms are a published tariff. SRP is a political subdivision of the state, governed by its own elected board, and is not ACC rate-regulated. Refund language learned on one side of the line does not transfer to the other.
| APS | SRP | |
|---|---|---|
| Governing document | ACC Service Schedule 3, Revision 16, effective 8 March 2024 (A.C.C. No. 6217, Decision No. 79293) | SRP Rules and Regulations, last revised 3 November 2025 |
| Who sets the rules | The Arizona Corporation Commission | SRP's own elected District Governing Board |
| When you pay | Signed Line Extension Agreement plus advance payment of all project costs before APS starts construction (§9.1(A)) | Contribution in Aid of Construction under a written agreement |
| Refundable | Possibly. Economic feasibility runs over a five-year agreement and is reviewed at the end of year three and year five; anything unrefunded at five years becomes a non-refundable contribution (§9.4) | Generally not. CIAC is generally non-refundable, although SRP may refund unused design fees if a project is canceled before construction (§§4.7.3, 4.7.4) |
| Interest on your money | None — refundable advances are non-interest bearing (§2.5) | None (§4.7.3) |
| The threshold to watch | $25,000 of extension facilities cost changes which feasibility test applies (§9.4) | 1,000 feet. Any line or lateral extension beyond it is individually evaluated and must be agreed in writing (§§4.6.3, 5.3.3) |
For most commercial work at APS this means the full project cost is due at agreement signing, before a crew moves. That belongs in the budget at design stage, not in a footnote discovered at buyout.
Code, jurisdiction, and where we are not the right contractor
Arizona has no statewide building or electrical code. A.R.S. Title 9, Chapter 7, Article 3 lets cities and towns adopt codes by reference, and A.R.S. §11-861 lets the county adopt one for zoned unincorporated areas. Two jurisdictions sharing a street can therefore enforce different NEC cycles, and the Valley spans three at once: Phoenix moved to the 2023 NEC on 1 August 2025 under Ordinance G-7397, Mesa on 8 January 2026, Glendale on 9 January 2026, Chandler under Ordinance 5108; Scottsdale is on the 2020 NEC; unincorporated Maricopa County is still on the 2017 NEC.
For Gilbert, Peoria and Tempe we publish no edition. The codified ordinances point one way, but we could not confirm currency from a primary source, so we confirm by phone with that city's building department before design. Expect any contractor working those three to make that call.
One local amendment reaches service and feeder work directly. Phoenix, unincorporated Maricopa County and Glendale all amend NEC 250.118 item (4) so that electrical metallic tubing requires an additional wire-type equipment grounding conductor. EMT alone is not an acceptable EGC there. On a large feeder run that is real money, and it has to be in the bid.
Gear sitting outdoors here is an enclosure-selection problem as much as an electrical one. NEC 110.28 and Table 110.28 govern enclosure type by location, and Type 3R is rainproof with no windblown-dust requirement at all — Type 4 and 4X are the ones built against windblown dust. In haboob country, 3R is often the wrong default for a free-standing outdoor section.
Where we will tell you to call somebody else
- We do not energize anything. Only utility employees do, at both APS and SRP.
- We do not hold a professional engineer's seal in-house. Where a stamped design or a study is required we coordinate a licensed Arizona PE and say which parts are ours. See electrical engineering and power system studies.
- We will not take a service swap that skips the utility application or the AHJ clearance. Neither utility will energize it, so there is nothing to buy.
- Trouble calls are not our work. This is scheduled, permitted scope: new services, gear replacements, distribution, and the underground that feeds it.
- If the switchboard is already built with a non-conforming meter section, we will say so before mobilizing. That is a procurement problem, and field labor does not solve it.
Send the one-line, the load calculation and the site plan early and we will tell you what the serving utility is going to say about them. Bid requests: (602) 396-5216, or the contact form. Office hours are Monday to Thursday 6:00 AM to 3:00 PM, Friday 6:00 AM to 2:00 PM.
Frequently asked questions
At what amperage does a Phoenix commercial service become CT-metered?
Above 200 amps, at both utilities. APS ESRM 302.9 requires EUSERC-approved CT-rated meter enclosures for all commercial sites above 200 amps, and EUSERC-approved test blocks and bypass provisions for self-contained services 200 amps and below. SRP gets to the same place differently: its Electric Service Specifications accept meter sockets rated 100, 200 and 400 amps, and the 400 amp Class 320 socket is residential only. So a commercial service over 200 amps at SRP is CT-rated as well. Budget the CT cabinet, the instrument transformer wiring and the extra submittal time from the start rather than discovering the threshold at buyout.
Do I really have to get the switchboard approved before it is manufactured?
At APS, yes. ESRM 302.9 requires every commercial meter enclosure to be submitted through an APS representative for review and approval before the equipment is manufactured, along with one-lines showing the neutral-to-ground bond link, the EUSERC page references, the ampacity, dimensions, voltage, phase, bus bracing, the number of padlockable service disconnects and the accurate street address. A separate application is required on top of that if the gear includes any connection or provision for an inverter or a generator. At SRP, shop drawings go to the shop drawing email address, and the two thresholds in SRP's own document differ, so we submit at the lower one and confirm with SRP Distribution Design.
Who trenches, and who sets the transformer?
The customer trenches, installs the conduit and provides the transformer pad. The utility sets the transformer, owns the meter, and furnishes and installs the current transformers and test switches. That split holds at both APS and SRP. APS stakes the trench and equipment locations and inspects the trench and pads before you cover anything. SRP requires the same inspections and, under its Rules, the customer does all trenching, backfill, boring and conduit or pays a contribution in aid of construction for SRP to do it. Arizona 811 has to be contacted at least three days before excavation.
What changed with SRP Customer-Owned Service?
SRP no longer permits Customer-Owned Service after 6 July 2026, per Note 6 in Section 3 of the Electric Service Specifications. Existing customer-owned conductors can be retained for maintenance, modifications, like-for-like replacements and right-sized service installations, but new work does not get that option. Where existing conductors are retained, the point of delivery stays at the transformer secondary bushings, the customer owns and maintains the cable, SRP will install connectors only where the cable is 750 MCM aluminum or copper, and an SRP representative has to be present when those connectors are installed. If you have a standard detail built around customer-owned secondary, it needs revisiting for any SRP job.
How long does a new commercial service take?
Neither utility publishes a committed timeline and we will not invent one. APS says only that project timelines vary by job complexity and current turnaround times. What we can tell you is what controls the clock: the switchboard lead time, the enclosure submittal and approval, the utility's own design and crew scheduling, the trench and conduit inspection, the AHJ clearance, and finally the utility setting the meter. The submittal and the application are the parts a project team can actually pull forward, which is why we start them at design rather than at mobilization.
How do I find out whether APS or SRP serves my site?
Do not assume from the city name or the ZIP code. SRP's own city list says served all or in part, and Phoenix, Scottsdale, Glendale, Peoria and Avondale appear on it while APS also serves parts of each. The reliable methods are reading the utility name off an existing bill at the site, checking the APS Phoenix metro service territory map, requesting an SRP facility map, or calling APS at 602-371-7171 or SRP at 602-236-8888. Downtown Mesa is the trap worth knowing about: the City of Mesa runs its own municipal electric utility over roughly 5.5 square miles centered on downtown, serving more than 18,000 customers, while SRP serves the rest of the city.
Which NEC edition applies to my service upgrade?
It depends entirely on the jurisdiction, because Arizona has no statewide building or electrical code. Phoenix has enforced the 2023 NEC since 1 August 2025, Mesa since 8 January 2026 and Glendale since 9 January 2026, Chandler adopted the 2023 NEC by ordinance, Scottsdale is on the 2020 NEC, and unincorporated Maricopa County is still on the 2017 NEC. For Gilbert, Peoria and Tempe we confirm the current edition directly with that city's building department before design rather than relying on a published summary. Also remember that Phoenix, unincorporated Maricopa County and Glendale all amend NEC 250.118 so that EMT alone is not an acceptable equipment grounding conductor.
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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.