Why One GC Relationship Can Scare a Buyer Off Your Electrical Business

The owner had been running his electrical shop for twenty-three years — six trucks, a couple of master electricians, and the kind of clean book most contractors envy. About 55% of the revenue came from one general contractor he'd worked alongside since the early 2000s. Two phone calls a week, every job on time, paid in 28 days. When the broker called it a "blue-chip relationship," nobody at the kitchen table disagreed. Then the buyer's analyst showed up with a single spreadsheet column — revenue by customer — and the room got quiet. The next call from the buyer started with: "We're going to need to talk about the GC."

That gap — between a long-running relationship and customer concentration a buyer can underwrite — is the loudest single thing that re-prices electrical deals at the table. (The shop here is illustrative; the way a buyer reads it is not.)

A long relationship is not the same word as a diversified book

It's an easy mistake on an electrical book in particular. You won the GC's trust years ago, you know how their PMs run a job, your crews don't get bounced off a site for being slow on a punch list — so the work compounds. That's a real asset. It's also exactly what makes the concentration so painful: the same trust that earned the share is the trust that doesn't transfer when the truck has a new name on it.

• A long relationship — the GC keeps calling because you answer the phone, your foreman walked their last three jobs, and the change-order culture is something the two of you negotiated over a decade. Real, valuable, owner-shaped.
• A diversified book — revenue spread across enough customers that any one of them leaving doesn't break the model. The work that a buyer can underwrite without you on the truck.

A buyer prices the second one higher because every dollar of revenue concentrated in a single account carries an exit risk: the account leaves with the seller, slows down during the transition, gets bid out by the GC's new procurement team, or quietly normalizes back to industry share once the founder isn't in the room. The first one is your moat. The second one is theirs.

What an offers.ai electrical read actually counts

This is where it gets concrete — and where our engine looks first when it reads an electrical QuickBooks file. We don't take "they love us" or "we've worked with them since '02" on faith. We rebuild the revenue book from the invoice ledger and compute three measures of concentration directly:

• Largest customer % — what share of the trailing-twelve revenue came from the single biggest account.
• Top-10 customer % — share from the ten largest combined.
• Top-20 customer % — share from the twenty largest combined.

That's the picture a buyer's analyst is going to build from the same ledger you're going to hand them — so you may as well see it first. On an electrical book, the benchmark a buyer is looking for is a healthy top-customer ceiling around 30% of revenue. Above that line, the conversation turns from "what's this worth" to "how do we structure around the risk." It still sells. It just doesn't sell at the same multiple.

It's worth saying out loud: this is also where an SBA-backed buyer's lender starts pushing back. Internal concentration policies vary by lender, but single-customer revenue above roughly the 20–30% range typically triggers extra underwriting on an SBA 7(a) acquisition — additional documentation on the relationship, sometimes an earn-out or contingent escrow, sometimes a re-cut deal. The lender's worry and the buyer's worry are the same worry.

Illustrative: a $3M electrical contractor with $500K of EBITDA, whose biggest customer — one regional GC — drove 55% of revenue over the last three years. The owner read that as a strength: thirteen unbroken years of work. The buyer read the same line as a single-point-of-failure on a five-year hold. The deal still moved, but the lead bid came in 0.7× of EBITDA below where the broker had run the comp — and the structure shifted from cash-at-close to a healthy earn-out tied to the GC's revenue retention. Same shop, same EBITDA, a different price for whose book it is.

What it costs in the multiple

This isn't a soft point — it moves the number directly. Electrical service businesses trade in roughly a 2.5×–8.0× EBITDA band, with a typical deal near 5.0×, and where you land inside it is set largely by the things a buyer's diligence team can rebuild from your books — concentration, recurring share, license picture, and estimating discipline. The good news is the same engine that measures the risks measures the levers:

Multiple band and value-driver ranges computed by the offers.ai engine for electrical; dollar figures are illustrative for a representative $500K-EBITDA shop — your real number comes from your books.

At ~$500K of EBITDA, every 0.1× of multiple is about $50K of enterprise value. The arithmetic on the GC story is straightforward: if concentration alone costs you 0.5× on the multiple, that's roughly $250K of price the deal walks in carrying. Layer on a buyer who wants 25% of the price held back in a GC-retention earn-out and the proceeds at close land lower still — for revenue the seller could have started diversifying eighteen months earlier.

Recurring revenue is the other half of the same story. The electrical benchmark for recurring is ~15% of revenue — structurally lower than HVAC (~30%) or plumbing (~25%), because the trade skews project-led. That's the floor a buyer expects on an electrical book; clearing it materially is how project shops earn the higher end of the band. Service contracts, PM agreements, and monitoring revenue don't have to replace GC project work — they just have to dilute it.

How to read your own concentration before a buyer does

You don't need our software to start. Open QuickBooks and pull:

• Revenue by customer, trailing twelve months. Sort largest to smallest. The percentage at the top of that list is the single number a buyer's analyst will write down first. If it's north of 30% on an electrical book, you've found the conversation.
• Top-10 share. Add up the ten largest accounts. If those ten are 75% or more of the revenue, the book is dense — workable, but the buyer will want to see what's underneath the top end.
• Recurring vs project mix. Service contracts, maintenance agreements, monitoring revenue, anything billed on a schedule rather than per-project. Against the ~15% electrical benchmark, where do you sit?
• Margin against the benchmark. Gross margin around 28% and EBITDA margin around 10% on a healthy electrical book. Heavy single-customer concentration sometimes hides a margin compression — the big GC has more leverage on your bid and your change orders than ten medium customers would, and the books quietly absorb it.
• Project pipeline outside the top account. Even concentration up to the line gets repriced less harshly when the smaller customers are growing. A buyer is buying the slope, not just the snapshot.

Two outcomes are possible from that exercise. Either the top of your list is closer to that 30% line than the gut said — and you can defend the multiple. Or it isn't, and you've found the exact lever a buyer is going to use against you, with 12–24 months to move the number before you go to market.

Common mistakes and buyer red flags

When an electrical book gets repriced on a concentration attack, it usually traces back to one of these.

• "They've been with us thirteen years." A buyer's response: and how many of those years featured the founder personally walking the GC's biggest jobs? Tenure is a signal, not a substitute for diversification.
• "It's a great GC, they'd never leave." Maybe true. But a buyer underwrites the downside, and the downside of a 55% relationship is a model that doesn't survive its loss. A risk doesn't have to be likely to be priced.
• Master-license risk stacked on top. If the single qualifying license and the single largest customer are both held by the owner, the buyer is looking at two single-points-of-failure that travel together. Each of them costs less when the other is solved.
• Concentration buried in a parent. Sometimes the "top customer" on the report is actually five subsidiaries of the same parent — and the buyer's analyst is going to roll them up. Pre-roll-up them yourself, on your own report, before diligence does it for you.
• Project mix with no recurring layer underneath. Heavy project + high concentration is the worst pairing for an electrical book. Even a thin layer of recurring service or monitoring revenue under the project work materially shifts the conversation.
• A pipeline that depends on the GC's pipeline. If your forward backlog is mostly extensions of work for the concentrated customer, the buyer treats the backlog at a discount, too — it isn't independent of the risk it's supposed to mitigate.

The takeaway

A long GC relationship is a real asset — keep it. It's just not the asset a buyer is paying the premium on, because the things that make it valuable to you (your relationship, your read of their PMs, your read of their pay practices) are the things that don't transfer cleanly at close. If your largest customer is well above the ~30% electrical line, that's the gap a buyer will push on, and you've got 12–24 months to widen the book — bring on two or three medium accounts, layer in service contracts and monitoring revenue, get the recurring share moving toward and through that ~15% floor — before you go to market. Same shop, a different shape of revenue on the file.

This is exactly the kind of gap offers.ai surfaces from your real books — the largest-customer share, the top-10 picture, the recurring vs project mix, and the value drivers that move your multiple — before a buyer rebuilds it for you. See it on the electrical overview, or run the free diagnostic. (For the umbrella version of this lesson across trades, start with recurring revenue vs repeat revenue; for how the same shape plays out in HVAC, the valuation walkthrough covers it with a different vertical's numbers.)

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Sources

1. Electrical EBITDA multiple band (2.5×–8.0×, typical ~5.0×), recurring-revenue benchmark (~15% of revenue), gross-margin benchmark (~28%), EBITDA-margin benchmark (~10%), top-customer ceiling (~30%), YoY growth norm (~5.2%), and the recurring / license / estimating value-driver lifts at a representative $500K-EBITDA electrical contractor — computed by the offers.ai engine. Engine values verified 2026-06-22.
2. Customer concentration measures (largest-customer %, top-10 %, top-20 % of revenue) — computed by the offers.ai engine over the trailing window.
3. U.S. Small Business Administration — SOP 50 10 (7(a) lender guidance) — single-customer revenue concentration is treated as a credit-risk factor in 7(a) acquisition underwriting; individual lender policies on single-customer caps typically sit in the 20–30% range. https://www.sba.gov/document/sop-50-10-lender-development-company-loan-programs
4. BizBuySell Insight Report (quarterly) — main-street cash-flow sale multiples; customer-concentration risk is a consistent repricing factor in trade-business sales. https://www.bizbuysell.com/insight-report/
5. IBBA & M&A Source — Market Pulse Report — customer diversification is among the most-cited multiple drivers in lower-middle-market SMB transactions. https://www.ibba.org/resources/market-pulse/