When Electrical Contracts Cost More to Deliver Than the Tender Allowed

When a commercial electrical contractor submits a tender in September, wins it in December, and mobilizes in March, there is a problem that does not appear on the tender document. The labour rate priced in September is no longer the rate that will be paid in the spring. The cable priced at September wholesale costs may have moved by the time purchase orders go out. And the fixed-price contract signed after award does not flex to accommodate either movement. For contractors competing on commercial fit-out and new-build electrical work, this time-shift between pricing and delivery is one of the more reliable ways to see a profitable-looking tender become a break-even job.

How Labour Costs Move After an Electrical Tender

The Joint Industry Board (JIB) sets nationally agreed rates for employed electricians in the UK and reviews them annually. From January 2026, the JIB applied a 3.95% increase to all graded operative rates - part of a three-year agreement that schedules further increases of 4.6% from January 2027 and 4.85% from January 2028.

For a contractor with a significant labour element in a multi-month contract, that annual uplift lands on day one of the new year regardless of when the contract was priced. A tender submitted in Q3 of the prior year, based on pre-January rates, does not automatically adjust. The contractor absorbs the difference.

The scale of the gap depends on the size of the labour element. On a contract with £200,000 of directly employed labour, a 3.95% JIB uplift represents around £7,900 in additional cost that was not in the original price. On a larger commercial installation with £400,000 of labour, the figure climbs toward £16,000. Neither amount is trivial when electrical subcontractors are working to the margins typical of fixed-price commercial work.

Labour cost pressure is not limited to the JIB agreement. The BCIS Labour Cost Index rose by 7.1% year on year in Q2 2025, with costs forecast to continue rising. Skills shortages in MEP and specialist electrical trades mean rates for self-employed electricians and specialist subcontractors can move faster than the published JIB schedule suggests. A contractor employing a mix of directly employed and self-employed operatives is exposed to both sets of pressures simultaneously.

The Material Side: Cable, Switchgear, and Timing

Labour costs follow a published schedule. Material pricing does not - it responds to commodity markets, supply chain availability, and import costs, none of which follow a predictable annual pattern.

For commercial electrical contractors, the key material categories are cable (copper-dependent), switchgear, distribution boards, and containment systems. Copper is the underlying commodity driver for cable pricing, and copper prices respond to global demand signals - particularly demand from electric vehicle manufacturing and grid infrastructure investment, both of which have been growing consistently.

The BCIS General Building Cost Index - covering labour, plant, and materials - rose by 3.8% in the 12 months to March 2026. Material prices across all construction work rose by 2.6% over the same period, but that headline figure masks sharper category-level movements. Fabricated structural steel rose by 8.2% over the same period. The pattern across construction is that aggregate figures conceal substantial variation depending on which materials a specific trade uses.

For electrical contractors on supply-and-fix contracts, the timing problem is specific: material costs must be quoted at tender stage, but purchase orders for cable, containment, and switchgear are typically raised weeks or months after contract award. A three-month gap between tender and bulk material ordering is common on commercial fit-out projects. A six-month gap on larger new-build installations is not unusual.

What Fixed-Price Contracts Actually Lock In

Most commercial electrical subcontracts are awarded on fixed-price terms. That is standard practice, and clients and main contractors expect it. The difficulty is that fixed-price means the contractor has agreed to deliver at the agreed sum - it does not mean costs inside the contract are fixed.

Industry analysis from May 2026 illustrates the scale. A contractor on a £1.5m fixed-price contract experiencing a 7% labour cost increase on a £450,000 labour element loses around £31,500 in margin. A 3% material cost rise on a £600,000 materials element adds another £18,000. That is approximately £50,000 of margin erosion on a contract originally expected to generate £150,000 net profit - roughly a third of the anticipated return, lost not through poor execution but through cost movements that occurred after the price was agreed.

Where retention is set at the standard 5% and payment flows through monthly valuations and applications, the contractor's cash position deteriorates further. Working capital is tied up for the project duration at a point when the cost of borrowing remains elevated.

Roughly a third of the expected net profit on a typical fixed-price commercial electrical contract can be absorbed by labour and material cost movements that happen after tender - before anyone has picked up a tool.

The contractors who manage this most effectively are not necessarily winning more work or charging materially higher prices. They are structuring their tenders and contracts differently, before the work starts.

Building Cost Reality Into Tender Submissions

Three practical adjustments are changing the margin position for electrical contractors who regularly price multi-month commercial work.

The first is shortening fixed-price validity windows. A tender validity period of 30 to 60 days is appropriate for most commercial electrical subcontracts. Holding a price open for six to twelve months while costs are rising quarterly is a risk that does not need to be offered as a standard commercial term.

The second is making labour rate assumptions explicit in the tender document. Stating that pricing is based on the current JIB schedule and that any agreed JIB uplift applying after the tender date will be treated as a variation is not unusual on larger commercial projects. It converts a hidden assumption into a visible contract position. A client or main contractor who objects to that clause is communicating something useful about how they intend to manage the contract.

The third is tracking cost performance on live contracts monthly. Comparing quoted labour hours and material costs against actuals - job by job, not at final account - is the only way to know whether margin is holding or eroding while there is still time to take corrective action. A cost review at practical completion rarely changes anything that could have been addressed mid-project.

Electrical contractors who lose margin on commercial work often know the problem exists. They feel it in the gap between a full order book and a disappointing set of year-end accounts. The gap between tender and delivery is where that difference is made - and it is controllable. The labour cost movements are on a published schedule. The material risks are identifiable at pricing stage. Building both into tender submissions as explicit assumptions rather than silent risks is the adjustment that changes the pattern.

Sources

• Construction Cost Inflation: How Contractors Can Protect Margins When Materials And Payroll Costs RiseSCC-CA · accessed 2026-07-18
• UK Construction Cost Inflation 2026 GuideJulian Hobbs & Co · accessed 2026-07-18

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