A smooth labour histogram can be produced from an unbuildable programme. If the underlying quantities are incomplete, the rates use inconsistent definitions or several crews are assigned to the same restricted workfront, the chart gives precision without a credible delivery plan.
An electrical labour forecast should explain three things: how much work remains, what effort that work requires and whether the site can accommodate the proposed deployment. The histogram is the final picture of that reasoning.
Break the work into measurable installation packages
Start with quantities tied to a defined area, system and activity. Cable containment, cable installation, terminations, equipment installation and testing need appropriate units and separate assumptions. Avoid averaging unlike work into a single rate simply because it belongs to the electrical package.
State the drawing revision and scope exclusions. Identify who owns changes to the quantity take-off. If shared infrastructure serves several halls, allocate its effort once and show which delivery phases depend on it; duplicating it across areas overstates resource demand.
Keep the rate and the working week on the same basis
Illustrative calculation, not a benchmark: assume a defined installation package contains 2,400 units of work at an estimated 0.75 productive labour-hours per unit. That is 1,800 productive hours. A person working a 40-hour week at an assumed 75% productive utilisation provides 30 productive hours per week. Delivering the package over four weeks therefore requires an average of 15 people: 1,800 ÷ (4 × 30).
This arithmetic is only as useful as its assumptions. If the original 0.75-hour rate already includes normal allowances for supervision, breaks or access, applying a second utilisation factor can double-count them. Define whether each rate represents productive time or paid time, and record what it includes.
| Input | Check before use |
|---|---|
| Quantity | Current scope, location, unit and revision. |
| Labour rate | Comparable method and explicit allowance basis. |
| Calendar | Working days, shift pattern and restrictions. |
| Resource capacity | Available skill mix, supervision and access equipment. |
| Remaining work | Measured progress plus approved scope changes. |
Check the workfront before adding people
The calculated average does not establish that fifteen people can work effectively in the available area. Walk the sequence with the delivery team. Confirm access, storage, platform positions, concurrent trades and the order in which containment, cable routes and equipment become available.
Also distinguish installers from specialists needed at particular stages. A general installation crew cannot automatically replace authorised testing personnel or a manufacturer’s representative. Show these scarce resources separately where they govern the sequence.
Shape the histogram around the method
Distribute the effort according to the intended installation sequence rather than evenly across every activity by default. Mobilisation, repetitive production, terminations and close-out can produce different demand profiles. Review peak weeks across areas: the total may be plausible while the assumed transfer of the same crew between locations is not.
Use the chart to test a small number of options. Could a second workfront genuinely be released earlier? Would a revised area sequence reduce a peak? Would a different shift need extra supervision or access restrictions? Document the assumptions behind the selected option.
Update remaining demand using evidence
Compare installed quantities and actual hours over a consistent period. Investigate the cause of divergence before projecting a rate forward: design change, access loss, unfamiliar work and recording errors require different responses. Reforecast the remaining scope, rather than assuming the original rate must recover by itself.
The useful weekly conversation is not “why is the histogram red?” It is which workfront, quantity or method has changed, and what that means for next month’s achievable output.
Put the next decision on a sound footing.
Our programme consultancy supports tender, construction and commissioning planning. For an existing programme, explore a schedule health check.