9 Electrical Estimating Mistakes That Kill Margins
Nine places electrical bids lose money, from unmeasured feeders and flat labor units at height to copper quote dates, scope splits, temp power, utility fees and commissioning.
LEEDS Estimating Team
Senior estimators
Electrical bids rarely lose money on the items that are counted. They lose it on the items that are assumed, the labor units that were never adjusted, and the scope that was neither included nor excluded. The nine below come from leveling and auditing hundreds of Division 26 estimates. Individually they are small. Together they routinely exceed the fee.
1. Feeders measured from the floor plan instead of the one-line
Floor plans show where panels sit, not how far the feeder runs. Scaling panel to panel on plan misses the vertical rise to the ceiling, the drop at each end, the routing around structure and the makeup inside the gear. On a four-story building that error is 30 to 50 feet per feeder, and on a 500 MCM copper run that is real money. Feeders to rooftop units and kitchen equipment, shown only on mechanical schedules, are missed entirely.
The fix: build the feeder schedule from the one-line and the panel schedules, then route each feeder on plan with a measured vertical at each end plus 10 feet of makeup per termination. Reconcile the count to the one-line before pricing. If the one-line shows 38 feeders and the takeoff has 34, four are coming out of your margin.
2. Flat labor units regardless of height
Published labor units assume installation at a working height up to about 10 feet with normal access. A 28-foot warehouse deck or a 16-foot retail ceiling is not that condition. Lifts move, material is staged, and every connection takes longer. Applying base units across the whole building understates labor by 20% or more on high-bay work.
| Working height | Typical labor adjustment | Access |
|---|---|---|
| Up to 10 ft | Base units | Ladder |
| 10 to 15 ft | +10% to +15% | Ladder or rolling scaffold |
| 15 to 20 ft | +20% to +25% | Scissor lift |
| 20 to 30 ft | +30% to +40% | Scissor or boom lift, two-person work |
| Over 30 ft | +45% to +60% | Boom lift, fall protection, staging |
The fix: zone the building by ceiling height during takeoff and apply the adjustment per zone, then add lift rental and the labor to move it as separate lines. The ranges above are the ones we apply; calibrate them to your own crews.
3. Pricing copper from a database
Wire and bus pricing in an estimating database is weeks old on the day it is used, and copper has moved more than 20% inside a year. A 400-foot run of four 500 MCM conductors plus ground can swing a few thousand dollars between a stale price and a fresh quote. Multiply across a feeder schedule and the error is larger than most contractors' fee.
The fix: quote all conductor and bus on bid day, record the quote date and vendor in the workbook, group copper-indexed items on their own tab, and carry a pricing-date clause in the proposal. If the bid is held more than a week, re-quote before signing.
4. Undercounting boxes, fittings and supports
A takeoff that counts devices and measures conduit but derives fittings with a flat percentage is guessing on 15 to 25% of the material. EMT needs a coupling every 10 feet, a connector at each box, a strap within 3 feet of every box and every 10 feet along the run, plus pull boxes on long runs and junction boxes above every device cluster.
The fix: let the software derive fittings per raceway run and per box rather than per project, then spot-check one corridor by hand. If the derived count is within 5% of the hand count, trust it. If it is not, the assembly definitions are wrong and every run is understated.
5. No clear split on fire alarm and low voltage
Divisions 27 and 28 show up on the electrical sheets, but who provides what varies by project. Sometimes the electrical sub provides pathways, backboxes and pull strings and a specialty contractor provides devices and head-end; sometimes the electrical sub carries all of it; sometimes the owner's vendor does. Bids that do not state the split either carry scope they will not get paid for or omit scope they will have to install.
The fix: read Division 01 and the bid form for the required breakdown, then price fire alarm, structured cabling, security and AV as separate alternates or tabs with written inclusions and exclusions. State who furnishes devices, who terminates, who programs and who tests.
6. Temporary power treated as someone else's problem
Temporary service, distribution, lighting and the monthly labor to maintain and relocate it are real costs over an 18-month project. Division 01 often assigns temporary power to the general contractor, who then expects the electrical sub to install it and the utility to bill the GC. If your bid assumes the GC carries it and the GC assumes you do, you install it for free.
The fix: price temp power as its own line with a service, distribution panels, string lighting by area and a monthly maintenance allowance across the schedule. State clearly whether it is included or excluded and who pays the consumption.
7. Utility fees and service lead times
Utility charges for the service, transformer, metering and primary conduit vary from one utility to the next. Some bill the owner, some bill the contractor, and some require the contractor to install the primary duct bank and pad to utility standards before a transformer is set. Transformer lead times have also stretched well past a year in many markets.
The fix: call the utility during the bid, get the fee schedule and standards in writing, and carry the fees as an excluded item or a documented allowance. Flag the transformer lead time in the proposal so the schedule risk is on the record.
8. Lighting controls priced as a few sensors
Current energy codes require occupancy, daylight and scheduling controls in most commercial spaces, and the fixture schedule often lists a networked control system that needs a controller per zone, sensors, wall stations, a gateway, factory programming and manufacturer startup. Estimators who count only the sensors on plan miss the programming, startup and commissioning that can be a third of the controls cost.
The fix: price controls from the lighting control schedule and sequence of operations, and get a quote from the controls representative that includes startup and programming hours. Carry your own labor for wiring and device installation separately.
9. Commissioning and closeout left out of labor
Commercial specifications now routinely require commissioning support, infrared scanning, arc flash studies, testing and labeling of every circuit, as-built drawings, O&M manuals and owner training. None has a quantity on the drawings, so none appears in a takeoff-driven estimate.
The fix: read Division 01 and the 26 08 00 commissioning section and build a closeout line with hours for each requirement. On a mid-size commercial project this is typically 2 to 4% of electrical labor.
If the feeder is not on your takeoff, it is on your dime.
A pre-bid checklist that catches most of it
- Reconcile the feeder count and total footage to the one-line.
- Confirm labor adjustments and lift costs are applied per ceiling-height zone.
- Confirm copper and gear quotes are dated within the last week and recorded in the workbook.
- Spot-check derived fittings against a hand count in one area.
- Confirm the Division 27 and 28 split is written into the proposal.
- Confirm temp power, utility fees, lighting controls startup and commissioning each have a line, included or excluded.
