Units of measure for electrical
Each piece of electrical work has its own unit, and keeping them apart is what makes the estimate checkable. These are the units estimators use and how each is measured.
| Item | Unit | How it's measured |
|---|---|---|
| Devices | each | Receptacles, switches and data boxes counted by type from the power and lighting plans. |
| Light fixtures | each | Counted by fixture type from the fixture schedule. |
| Branch conduit | LF | Measured home run and circuit routing, by size and type; often estimated per device on fit-outs. |
| Wire | LF | Conduit length × conductors per run, plus tails at boxes and panels. |
| Feeders | LF | Measured from the single-line diagram and riser, by size. |
| Gear and equipment | each | Panels, transformers, disconnects and equipment connections. |
How estimators take off electrical
- Count devices and fixtures. Count by type on each plan, color-coding as you go. These counts drive most of the labor.
- Measure feeders from the single line. Take each feeder's route and length, with conductor size and count.
- Measure or allow branch circuiting. Measure conduit on detailed jobs; on repetitive fit-outs, estimators often use a length per device from past jobs.
- Add wire, fittings and supports. Wire is conduit length times conductors plus tails. Fittings, straps and supports are typically an allowance on the conduit.
- Apply labor units or crew production. Price labor per unit (hours per device, per 100 ft of conduit) and adjust for height, access and occupied work.
Waste factors and order quantities
Waste covers cut-offs, breakage, laps and spillage, and it's added to the net quantity before rounding up to what the supplier sells. These are typical planning figures; your own job history is the better number.
| Item | Factor | Notes |
|---|---|---|
| Wire | 5 to 10% | Typical planning figure for tails, pulls and cut-offs. |
| Conduit | 5 to 10% | Typical planning figure for offsets and cut-offs; fittings priced separately. |
Crew production rates
Labor is quantity divided by production. These rates are per 8-hour crew-day for commercial work, from the same library as the crew-day production estimator: typical mid-range planning values with a low-to-high range, not a promise of output. Crew skill, layout, access and weather move them, and your own crews' records beat any library.
| Activity | Crew | Low | Typical | High | Labor |
|---|---|---|---|---|---|
| EMT conduit 3/4 in, with supports | 2 electricians | 250 | 320 LF | 400 | 5.0 hrs per 100 LF |
| Pull #12 THHN wire | 2 electricians | 2,000 | 2,500 LF | 3,200 | 0.6 hrs per 100 LF |
| Install and trim devices | 2 electricians | 40 | 55 each | 70 | 0.29 hrs per each |
| 2x4 LED troffers in grid ceiling | 2 electricians | 20 | 28 each | 35 | 0.57 hrs per each |
- EMT conduit 3/4 in, with supports 250 to 400 LF, typical 320
- Pull #12 THHN wire 2,000 to 3,200 LF, typical 2,500
- Install and trim devices 40 to 70 each, typical 55
- 2x4 LED troffers in grid ceiling 20 to 35 each, typical 28
Worked example: 600 devices on a tenant fit-out
The activity is install and trim devices, with a crew of 2 electricians at the typical rate of 55 each per crew-day:
- Crew-days: 600 each ÷ 55 = 10.9 crew-days.
- Labor hours: 10.9 crew-days × 2 workers × 8 hours = 175 hours.
- Range: 8.6 crew-days at the high rate to 15 at the low rate, a spread of 6.4 crew-days on the same quantity.
Multiply the labor hours by your burdened hourly cost to price the labor. The spread between the low and high rate is why production is the assumption to check first on a electrical bid: the same takeoff can carry very different labor. Run your own quantities in the crew-day production estimator, and get the burdened rate from the labor burden calculator.
What drives the cost
- Labor productivity. Height, ceiling access, occupied spaces and phasing change labor far more than material.
- Wiring method. EMT, MC cable and rigid conduit have very different labor per foot.
- Gear lead times. Switchgear and transformer pricing and lead times can move a bid; quotes should state validity.
- Low voltage and controls. Fire alarm, data and controls are often separate scopes and need to be clearly in or out.
Common exclusions and clarifications
A electrical price is only as good as the scope it describes. These exclusions come from our scope library for electrical (CSI 26 00 00); list the ones that apply so the GC levels your number fairly.
- Utility company charges, transformer pads and primary service work.
- Low-voltage, data, security, audio-visual and fire alarm systems unless listed as included.
- Control wiring for mechanical equipment.
- Trenching, backfill and concrete encasement in rock or unsuitable soils.
- Temporary power beyond one service drop.
- Light fixtures not listed on the fixture schedule or furnished by the owner.
Clarifications that often go with them:
- Fixture quantities per the fixture schedule; substitutions priced on request.
- Temporary power limited to one service drop.
Pick, edit and export these in the scope inclusions and exclusions library, or load them straight into a proposal with the bid proposal builder.
Free tools for electrical estimating
- Crew-day production estimator: turn electrical quantities into crew-days, duration and labor hours with the rates on this page.
- Labor burden calculator: find the true cost of a crew hour, with taxes, insurance and benefits.
- Scope inclusions and exclusions library: pick proposal-ready electrical exclusions and clarifications.
- Bid proposal builder: send a branded electrical proposal with the scope language loaded.