Case Study — Multifamily
Multifamily Podium Electrical Estimate — Phoenix, AZ
Project Overview
Full electrical estimate for a 5-over-2 podium multifamily project with 312 residential units, ground-floor retail, swimming pool amenity deck, and 2 levels of parking. Scope included: new 3000A service from APS, (2) 2000A distribution switchboards, (32) meter stacks with individual unit metering, (18) 277/480V panelboards, (8) 208/120V transformers, emergency egress lighting system with battery backup, full fire alarm system, parking garage EV infrastructure (20 spaces rough-in ready), amenity deck electrical (pool lighting, pump, kitchen, audio), and residential unit trim packages.
CSI MasterFormat Divisions Covered
26 05 00, 26 05 13, 26 05 33, 26 08 00, 26 09 23, 26 22 00, 26 24 00, 26 24 16, 26 27 26, 26 32 00, 26 36 00, 26 51 00, 28 31 00, 33 71 00
Estimating Challenges
- APS required the primary service to be underground, but Phoenix caliche soil conditions added $38,000 in rock excavation costs that were not in the standard trenching allowance
- NEC 310.15(B)(3)(c) ambient temperature correction for rooftop conduit runs in Phoenix summer conditions required a 124% ampacity adjustment — the original design used standard derating, requiring upsizing (6) feeder conduits by one trade size
- The swimming pool equipment electrical (pumps, heater, lights, sanitary) required NEC 680 compliance with bonding grid, GFCI protection for all pool-associated loads, and bonding of the pool shell rebar — the design showed only pump connections
- Unit meter stacks had varying apartment mix configurations (studio, 1BR, 2BR, 3BR) across 32 stacks — each stack required individual takeoff with breaker configurations matching unit types
Change Order Prevention
During the takeoff review process, our team identified the following scope gaps that would have become change orders if not caught at the estimating stage:
- Identified that the EV charging infrastructure rough-ins (20 spaces) required separate metering per APS requirements — the design showed connection to the main service without utility-approved metering — ($24,000)
- Caught that the amenity deck outdoor kitchen electrical (refrigeration, exhaust, lighting) was shown on the landscape drawings but not included in the MEP scope — ($14,000)
- Flagged that the parking garage ventilation fans (6 units) had exhaust-only electrical shown but required supply fans with interlocked controls per IMC — ($11,000)
Labor Forecasting
Used NECA MLU multifamily factors. Phoenix IBEW LU 640 rates. Applied 8% productivity reduction for summer work (June-September outdoor work limitations in 110+ degree conditions). Podium construction sequencing required coordination with the structural concrete pour schedule for underground conduit installation. Budgeted $42,000 for temporary construction power across the 24-month schedule.
Material Escalation Strategy
The primary material risk was copper — the ambient temperature correction required larger feeder conductors, increasing copper quantity by approximately 15%. Locked copper pricing at 60-day firm quotes with quarterly review. The meter stacks were procured as a single package with a 10% volume discount ($28,000 savings). All switchboard and transformer orders were placed within 30 days of award with firm pricing.
Budget Comparison
| Line Item | Initial Estimate | Final Bid | Variance |
|---|---|---|---|
| Service & Switchboard | $560,000 | $582,000 | +3.9% |
| Meter Stacks & Panels | $680,000 | $695,000 | +2.2% |
| Feeder Conductors (derated) | $412,000 | $476,000 | +15.5% |
| Lighting & Amenities | $528,000 | $552,000 | +4.5% |
| Fire Alarm & Life Safety | $196,000 | $204,000 | +4.1% |
| Labor | $1,024,000 | $1,076,000 | +5.1% |
| Total | $3,200,000 | $3,385,000 | +5.8% |
Risk Mitigation
Recommended early APS coordination meeting to confirm service requirements and EV metering configuration — caught the separate metering requirement before the bid was submitted. Also recommended a geotechnical investigation specifically for the service trench route to quantify caliche soil conditions — the $4,200 soil test identified the rock excavation requirement before the estimate was finalized rather than as a change order during excavation.
Result
The project was awarded at $3.38M. The post-award analysis showed only $18,000 in electrical change orders (all owner-directed scope changes). The ambient temperature derating adjustment alone saved $64,000 in potential rework. The APS coordination meeting prevented a 6-week utility approval delay. The contractor used our estimate to successfully negotiate with the owner on the caliche soil add.