Articles · Estimating
How to Price Electrical Work by Device Count (Assemblies)
Counting devices and pricing each one as a complete assembly is the fastest way to bid residential and light commercial work the same way every time.
6 min read · CircuitCount
What an assembly is
An assembly is everything it takes to install one item: the box, the device, the plate, an allowance of wire and the labor hours. Instead of pricing 47 separate parts, you count "12 receptacles, 6 switches, 8 downlights" and the price builds itself.
Example: a new-work duplex receptacle
| Part | Qty | Unit cost | Extended |
|---|---|---|---|
| 1-gang box | 1 | $0.75 | $0.75 |
| Tamper-resistant duplex receptacle | 1 | $2.00 | $2.00 |
| Wall plate | 1 | $1.00 | $1.00 |
| 12/2 NM cable | 20 ft | $0.73/ft | $14.60 |
| Material per receptacle | $18.35 | ||
Then add labor hours per receptacle, your labor rate, consumables, overhead and margin. Sample prices shown are typical public retail; use your own supplier's prices.
Start with 10 to 15 assemblies
Most service and remodel bids use the same short list: receptacles (new and old work), GFCI, exterior GFCI, single-pole and 3-way switches, dimmers, downlights, fixture and fan boxes, smoke alarms, dedicated 20A circuits, 240V circuits, and service work. Build those first.
Wire: use an average run, then adjust
Each assembly carries a typical wire length, like 20 feet per device or 50 feet for a home run. On a long run, add extra feet as its own line rather than changing the assembly. Your assemblies stay consistent and the odd job still gets priced right.
Labor: separate the unit from the conditions
Keep assembly hours for normal conditions. Then apply one job-wide factor for what makes this job harder: old work in finished walls, attics in summer, crawlspaces, occupied homes. A factor of 1.25 on a fished-wall job is easier and more honest than editing every line.
Track and tune
After a few jobs, compare estimated hours to actual hours. If 3-way switches keep running long, raise that assembly's hours. Small corrections compound into accurate bids.
Price per 100 and per 1,000
Supply houses often quote boxes and fittings per 100 (C) and wire per 1,000 feet (M). Store prices in the same units so you can update them straight from an invoice without converting.
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This article is general business math for electrical contractors. It is not legal, tax, accounting or code advice. Use your own numbers.