Start with the scope, not the total
Read the scope of works first and ignore the price. A scope that says "electrical installation as per plan" is not a scope, it is a reference to another document, and the other document may be a drawing with no device schedule. The test is simple: could a different contractor price this scope and arrive at the same installation? If the answer is no, the estimate cannot be compared with anything, including a revised version of itself.
Ask for the estimate to be read against the design: devices, circuits, cable routes, panel composition. If there is no design, the estimate is an allowance, and allowances move. Anything described as an allowance should carry a stated quantity and a stated unit, or it is a placeholder.
The twelve checks
1. Is there a device count? Sockets, switches, luminaires, data points, and their quantities. No count means the number is a guess.
2. Are circuits defined? The number of ways in the panel, and what each one feeds. A quote that names a 12-way board without a schedule has not decided anything.
3. Is the cable specified by size and type? "Cable included" is not a specification. You want mm², core count, insulation and whether it is armoured, LSZH, or standard.
4. Are protective devices itemised? Breakers, RCDs or RCBOs, surge protection, main switch. Type and rating, not a lump sum for "protection".
5. Is the panel itself priced as equipment or as labour? An enclosure, a DIN rail and a set of modules are three different purchases.
6. Does the estimate include containment? Trunking, conduit, tray, and the fixings. Containment is the single most common omission and the most common variation order.
7. Is chasing and making good included? If walls are to be chased, someone pays for the plaster and the paint. Check whether it is the electrician, the builder, or you.
8. Is testing and certification a separate line? Insulation resistance, continuity, loop impedance, RCD trip times, and the certificate. If it is "included", ask what document you receive at handover.
9. Is access equipment covered? A tower or a scissor lift for high ceilings can exceed the labour for the wiring itself.
10. Are working hours stated? Day rate assumes day work. Evening or weekend work in an occupied building is a different rate and often a different productivity.
11. Is there a variation mechanism? Unit rates for extra points, or a written process. Without one, every change is a negotiation under pressure.
12. Is the payment schedule tied to milestones? Deposit, first fix, second fix, commissioning, retention. A schedule that front-loads payment removes your leverage.
What good looks like
| Element | Weak estimate | Usable estimate |
|---|---|---|
| Scope | "As per plan" | Room-by-room list with quantities |
| Circuits | Board size only | Schedule: way, description, cable, breaker |
| Cable | "Included" | Size, type, route assumption |
| Containment | Missing | Linear metres by type |
| Testing | Mentioned | Named certificate and test list |
| Variations | Silent | Unit rates or written change process |
| Payment | 50% up front | Milestones with retention |
| Programme | Absent | Duration and dependencies |
The right-hand column is not a premium product. It is the minimum needed to compare two offers.
The red flags
A single red flag is a question. Three is a pattern.
- A round number with no breakdown. Especially one that matches your budget exactly.
- Refusal to itemise. "We don't do that, we're tradesmen." Itemising is normal practice, not a trade secret.
- No site visit and no survey. A price for a building nobody measured is a price for a different building.
- Pressure to sign before the design is finished. Sometimes genuine scheduling, sometimes a way to lock scope you have not read.
- Certification promised verbally only. Get the certificate type in writing.
- Exclusions buried at the back in small type. Read the exclusions before the totals; they change the comparison more than the totals do.
- A price far below every other quote. Usually a missing scope item, occasionally a business that needs cash this month. Both cost you later.
- No physical address or registration number. Easy to check, rarely checked.
Compare like with like
The only fair comparison is a normalised one. Put every quote into the same table: same rooms, same device counts, same cable specification, same testing scope, same exclusions listed explicitly. Where a quote omits a line, do not assume it is free — mark it "not stated" and ask. A quote that is 20% cheaper because it excludes containment is not cheaper.
Normalising also protects you from the opposite error: rejecting a careful quote because it looks expensive next to a thin one. Once the missing lines are added back, the ranking often reverses.
If your design exists as a data set rather than a PDF, this step is mechanical: the bill of materials from the design is the checklist, and each quote is measured against it. That is the practical reason to produce the specification and BOM before tendering, rather than after.
The 30-minute routine
- Minutes 0–5: read the exclusions page first.
- Minutes 5–10: count devices on the plan, compare with the quote.
- Minutes 10–15: check cable sizes and protective devices are named.
- Minutes 15–20: look for containment, chasing, access equipment, testing.
- Minutes 20–25: check payment terms and variation mechanism.
- Minutes 25–30: write three questions. If the answers are evasive, that is your answer.
Keep the questions factual. "Which cable size is assumed for the kitchen circuit, and which breaker protects it?" is answerable in one line by anyone who priced the job.
Questions that get useful answers
- What is excluded, specifically?
- Which revision of the drawing is this priced against?
- Who supplies and installs the containment?
- What certificate do I receive, and who signs it?
- What is the unit rate for an additional socket point?
- How many days on site, and what do you need from me to start?
The last question matters more than it looks. Contractors price risk, and access risk is the largest single unknown on a refurbishment.
Where the design side helps
Most estimate disputes trace back to an incomplete design, not a dishonest contractor. If the panel schedule and cable schedule exist before tendering, the quote has something to be checked against, and variations have a baseline. Producing that baseline is now a browser job rather than a CAD project: import the plan, place devices, generate the schedule, export the BOM. You can run the flow on a demo project and see what a complete tender package looks like before you send it out.
For the pricing side of the same conversation, see what electrical design costs and how panel costs break down. Plans are on the pricing page.
Sources
- NFPA 70, National Electrical Code — nfpa.org
- IEC 60364 series, low-voltage electrical installations — webstore.iec.ch
- U.S. Bureau of Labor Statistics, electricians (labour market reference) — bls.gov
- Electrical Safety Foundation International, home electrical safety — esfi.org
- UK Government, Approved Document P (electrical safety) — gov.uk
Informational only, not legal or engineering advice. Certification requirements, deposit norms and contract law vary by country; check the rules in force where the work is done.
Three is the practical minimum for comparable work, and all three must be priced against the same design revision. Two quotes on different drawings tell you nothing except that drawings differ.
Not usually wrong — usually incomplete. Add back the missing containment, testing and making good, and the gap often closes. If it does not close, ask why.
A deposit for materials is normal in many markets; a large payment before any work starts is not. Tie payments to first fix, second fix and commissioning, and keep a retention until the certificate is issued.
Treat it as a scope risk rather than a personality clash. You cannot manage a budget you cannot see, and you cannot compare an offer you cannot decompose.
Yes, at the level of completeness: counts, named components, exclusions, payment terms. You are checking that the document answers questions, not that the engineering is right. The engineering check needs either a designer or a rule-based review.
No. It produces the design, the schedule and the bill of materials you check prices against. It does not know local rates, and it does not negotiate for you.
Design it in the browser
Turn the plan into circuits, a panel schedule, a single-line diagram and a calculated bill of materials. Start free or open the demo.
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