25 Questions to Ask a Power Plant EPC Contractor Before You Sign

The most important questions to ask an EPC contractor cover five areas: track record on plants like yours, scope and engineering ownership, procurement and long-lead equipment control, construction safety and commissioning, and how the contract allocates risk, security and handover. Ask every bidder the same questions before you sign.

Most checklists stop at the question. This one goes further. For each of the 25 questions you get why it matters, what a strong answer sounds like, and the red-flag answer that should move a bidder down your shortlist. 

We write from the other side of the table. Prismecs is an EPC and EPCM contractor for gas turbine, reciprocating engine, BESS and hybrid power plants, and we answer these questions in every bid we submit.  

What Is a Power Plant EPC Contract? 

A power plant EPC (engineering, procurement and construction) contract makes one company responsible for designing, buying equipment for, building and commissioning a plant, usually for a fixed price and a guaranteed completion date. The owner gets one point of accountability. The contractor takes most of the cost, schedule and performance risk and prices a premium for it. 

Common variants are lump-sum turnkey (LSTK), EPCC (commissioning named in scope), and contracts built on the FIDIC Silver Book, the international standard form for turnkey EPC work. Under EPCM, the contractor manages engineering, procurement and construction for the owner, but the owner holds the construction contracts and more of the risk. For a deeper overview, read our power plant EPC guide. 

EPC vs. EPCM: which questions change 

Not sure which model fits your plant? Our EPC vs. EPCM comparison walks through how to decide.

Why the Right Questions Pay Off Before Notice to Proceed 

Most expensive plant problems are locked in before anyone mobilizes to site. Construction Industry Institute (CII) benchmarking, summarized by NIST, puts mean field rework above 3% of construction-phase cost on heavy industrial projects. CII's original 1989 rework study found that design deviations (changes, errors and omissions) caused roughly 80% of the added cost, while construction deviations caused only about 20%. 

That is why the lowest bid is a weak predictor of the final price. A 2023 peer-reviewed study in Engineering, Construction and Architectural Management ranked 16 EPC contractor selection criteria by expert consensus. Past performance, project understanding, technical attributes and key personnel came first. Cost ranked twelfth. 

The 25 questions below are built around that ranking. They help you compare bids on what actually decides the outcome, then hold the winning bidder to its answers in the contract. 

The EPC Bid Comparison Scorecard 

Score each bidder 1 to 5 on every criterion, multiply by the weight, and compare totals. The weights below are a starting point for a gas turbine or BESS plant; adjust them to your project's risk profile before bids arrive, not after. 

Questions About Experience, Track Record and Security 

1. Have you delivered plants of this technology, size and configuration? 

Why it matters: A good solar EPC is not automatically a good gas turbine or BESS EPC. Fuel systems, HRSGs, battery augmentation and grid code compliance are different disciplines. 

Strong answer: A list of named plants with technology, MW/MWh, location, scope (full EPC or partial), contract model and completion date. The bidder can explain one problem on a comparable job and how it was fixed. 

Red flag: Capacity totals with no project names, or "similar" projects that turn out to be a different technology or a fraction of your size. 

2. Can we speak to recent owners, and how did those projects perform against plan? 

Why it matters: References and delivery data test the same thing: whether past promises were kept. Ask for both together. 

Strong answer: Two or three owner contacts from projects finished in the last three to five years, plus actual vs. planned completion dates and final vs. contract price, with each variance explained. 

Red flag: References only from equipment vendors or partners, or self-reported success rates with no definition of what was measured. 

3. What security package will you provide, and from whom? 

Why it matters: Your protection if the contractor fails is only as good as the paper behind it. International power projects rarely rely on US-style surety bonding alone. 

Strong answer: A clear package: a performance bond or bank guarantee (commonly around 10% of contract price), an advance payment guarantee matching any advance, retention or a retention bond, and a parent company guarantee (PCG) where the contracting entity is a subsidiary. Audited financial statements and the issuing bank or surety are named. Lenders' requirements, including letters of credit, are addressed. 

Red flag: Security offered only by a thinly capitalized project subsidiary, or reluctance to share audited financials. 

4. Have you delivered in this country, grid and regulatory environment? 

Why it matters: Permitting, local content rules, labor law, customs, climate and grid codes all hit the schedule. Remote and frontier sites add logistics risk that a first-world track record does not prove. 

Strong answer: Named projects in the same region or with similar constraints, a permitting plan with responsibilities assigned, and a logistics plan for oversized loads. 

Red flag: "We'll partner with a local firm" with no named partner, or a schedule that assumes home-market permitting times. 

Questions About Scope, Engineering and Equipment 

5. What is in your scope, and what is excluded? 

Why it matters: Exclusions are where change orders are born. Two bids at the same price can describe very different plants. 

Strong answer: A line-by-line scope matrix covering engineering, equipment, civil works, interconnection, permits, commissioning, spares and training, with every owner responsibility written out. 

Red flag: A short scope narrative and a long exclusions list, or exclusions such as "subsurface conditions" and "utility upgrades" with no allowance. 

6. Who does the engineering, and how much is in-house? 

Why it matters: When design is outsourced, accountability blurs and owner comments take longer to close. 

Strong answer: Discipline-by-discipline split (mechanical, electrical, civil, I&C, protection) with named lead engineers, and who stamps the drawings. 

Red flag: "We use a network of partners" with no names, or a single lead engineer spread across several bids. 

7. Which codes and performance test standards will govern the plant? 

Why it matters: Performance guarantees are worthless if the test method is vague. The test code decides whether a shortfall triggers LDs. 

Strong answer: Named design codes (IEEE, NFPA, ASME, IEC, local grid code) and named test codes: ASME PTC 22 for gas turbines, ASME PTC 46 for overall plant performance, and agreed capacity and round-trip efficiency test procedures for BESS. Correction curves and test tolerances are attached to the contract. 

Red flag: "Industry standard testing" or test procedures "to be agreed after award." 

8. How will design reviews and owner approvals work? 

Why it matters: Late design changes ripple into procurement and site work, where they cost the most. 

Strong answer: Fixed review gates (for example 30%, 60%, 90% and issued-for-construction), review periods in days, and a log showing how each owner comment is closed. 

Red flag: No review gates, or a schedule that assumes owner approvals in a few days. 

9. Are you OEM-agnostic, or tied to specific equipment brands? 

Why it matters: A contractor locked to one turbine, inverter or battery supplier may price and schedule around that supplier, not your plant. 

Strong answer: A shortlist of qualified OEMs for each major package, the reason for the recommended choice, and disclosure of any commercial ties. 

Red flag: One brand offered with no alternatives and no disclosure of the relationship. 

10. If we supply the turbines or transformers, who wraps their performance? 

Why it matters: With long lead times, many owners now reserve turbine and transformer slots themselves before choosing an EPC. Owner-furnished equipment (OFE) creates an interface gap: if the plant misses its guarantees, the contractor blames the equipment, and the OEM blames the installation. 

Strong answer: A clear position on the "wrap": either the EPC takes over the OEM contract by assignment and guarantees plant performance, or the contract states exactly which guarantees the OEM keeps and how interface risk is shared. Delivery delays on OFE have a defined schedule remedy. 

Red flag: Full plant guarantees offered on paper, with an exclusion buried elsewhere for "any defect in owner-furnished equipment." 

11. Who carries interconnection and site-condition risk? 

Why it matters: Grid connection delays and unforeseen ground conditions are two of the most common causes of late commercial operation. 

Strong answer: A split of interconnection work (plant side vs. utility side), who manages the utility relationship, geotechnical data the price relies on, and how unforeseen conditions are priced. 

Red flag: A fixed completion date with no stated assumptions on interconnection approval or soil conditions. 

Questions About Procurement and Supply Chain 

12. Which items are on the critical path, and how will you secure them? 

Why it matters: large power transformers, heavy-duty gas turbines, switchgear and battery systems now carry lead times often quoted at well over a year, and two years or more for some transformers and turbines. The plant cannot finish before its slowest delivery. 

Strong answer: A long-lead list with quoted lead times, which slots are already reserved, whether a limited notice to proceed (LNTP) is needed to lock them, and fallback options such as available inventory or refurbished units.

Red flag: A schedule that starts procurement at full notice to proceed with no LNTP, or lead times copied from pre-2023 catalogs. 

13. How do you qualify vendors and subcontractors, and inspect what they build? 

Why it matters: Most quality problems on site were made in a factory or by a subcontractor months earlier. 

Strong answer: An approved vendor list with qualification criteria, named subcontractors for major scopes, inspection and test plans, factory acceptance tests (FAT) with owner witness points for turbines, transformers and controls, and an expediting process. 

Red flag: Subcontractors "to be selected after award" for civil or electrical packages, or no owner witness rights at FAT. 

14. How are escalation, currency and tariff risk handled? 

Why it matters: Over a multi-year build, steel, copper, battery cells and imported equipment can move sharply in price, and tariff changes can land mid-project. 

Strong answer: A clear statement of what is fixed, what is indexed (and to which index), who carries currency exposure on imported equipment, and how tariff changes after bid date are treated. 

Red flag: A "fixed" price with a broad escalation or change-in-law clause that quietly shifts the risk back to you. 

15. How are logistics, customs and site storage managed? 

Why it matters: Oversized loads need route surveys and permits; equipment stored badly on site can lose its warranty before it runs. 

Strong answer: Route and port studies for heavy lifts, a named party for customs clearance and import duties, and a preservation plan for stored equipment. 

Red flag: Logistics listed as an owner responsibility or left out of the price. 

Questions About Construction, Safety and Commissioning 

16. What are your safety metrics, and how do you manage subcontractor safety? 

Why it matters: Safety performance is a proxy for how well a contractor plans and controls work. Construction and extraction workers recorded 1,032 fatal injuries in the US in 2024, according to the Bureau of Labor Statistics. 

Strong answer: Three to five years of TRIR (total recordable incident rate), LTIR (lost-time incident rate) and, for US work, EMR (experience modification rate), with hours worked so the rates can be compared. A site safety plan, and proof that subcontractors work to the same system. 

Red flag: "Zero harm" slogans with no rates, rates without hours worked, or subcontractor incidents excluded from the figures. 

17. Who will lead our project, and how will you report progress? 

Why it matters: The team and the reporting decide how early you hear about problems. 

Strong answer: Named project manager, construction manager and commissioning lead, with CVs and a contractual commitment for the project's duration. Weekly or monthly reports with critical-path updates, earned value and look-ahead schedules. 

Red flag: Key staff "to be confirmed," or the same names offered on several concurrent bids. 

18. What is your quality assurance and quality control plan? 

Why it matters: Rework starts with undocumented quality. A written system is your first defense. 

Strong answer: A QA/QC plan with inspection and test plans (ITPs), welding, cable and protection testing procedures, and a non-conformance log you can see. 

Red flag: Quality described as a site supervisor's responsibility, with no documented procedures. 

19. How do you define completion, and how will performance be tested? 

Why it matters: Money, LDs and risk all transfer at completion milestones. Vague definitions are where disputes start. 

Strong answer: Written definitions of each milestone. Mechanical completion: the plant is built and ready for commissioning. Substantial completion (or taking over): performance tests and a reliability run, commonly 72 hours or longer, are passed and the plant can operate commercially. Final completion: punch list closed and documentation handed over. Each has its test procedure, witness rights and the remedy if the plant falls short. 

Red flag: Substantial completion that can be declared before performance tests, or no reliability run at all. 

Questions About Contract Terms, Risk and Handover 

20. What contract form and pricing model are you proposing? 

Why it matters: Lump-sum turnkey, target price, cost-reimbursable and EPCM each move risk differently, and the base form (FIDIC Silver Book, Yellow Book or a bespoke contract) sets the starting point for every clause. 

Strong answer: The proposed form named, a marked-up list of departures from it, and a clear reason the pricing model fits your project and lenders. 

Red flag: The contractor's own standard terms with no reference form, offered as "non-negotiable." 

21. What performance guarantees and liquidated damages will you accept? 

Why it matters: Liquidated damages (LDs) are often the owner's only remedy for delay and underperformance, so their size and caps matter more than the guarantee headline. 

Strong answer: Guarantees for completion date, net output, heat rate or efficiency, availability and emissions (plus capacity, round-trip efficiency and degradation for BESS). Delay LDs sized against your real daily revenue loss, performance LDs with a buy-down rate, and caps stated separately for delay, performance and in total. 

Red flag: Low LD rates that cost the contractor less than finishing late, or a combined cap so low the guarantees are symbolic. 

22. What is your limitation of liability, insurance cover and dispute route? 

Why it matters: These clauses decide what happens in the worst case, after everything else has gone wrong. 

Strong answer: An overall liability cap (often linked to the contract price) with standard carve-outs such as fraud, willful misconduct and third-party injury. Construction or erection all-risks insurance (CAR/EAR) with named insureds and deductibles. A tiered dispute route: site-level negotiation, then a dispute avoidance and adjudication board (DAAB) under FIDIC, then arbitration at a named seat. 

Red flag: A cap far below the contract price, insurance "to be arranged by owner," or disputes sent straight to courts in the contractor's home country. 

23. How are change orders priced and approved? 

Why it matters: Scope will move. The change process decides whether it moves fairly. 

Strong answer: A written procedure with notice periods, a schedule of labor rates and equipment markups, and a time bar for claims. 

Red flag: No rate schedule, or no time limit for the contractor to submit claims. 

24. What warranties, spare parts and training are included? 

Why it matters: These shape the first years of operation, when early failures are most likely. 

Strong answer: Defects liability periods for equipment and workmanship (commonly 12 to 24 months), a priced recommended spares list, and a training plan for operators and maintenance staff. 

Red flag: Warranties that only pass through OEM terms, with no contractor workmanship warranty. 

25. What does handover include, and who supports the plant after COD? 

Why it matters: A plant handed over without clean records or a ready O&M team loses availability in its first year. 

Strong answer: As-built drawings, O&M manuals, test records, control-system backups and a populated computerized maintenance management system (CMMS), plus an option for O&M or long-term service from the same team that built the plant. See Prismecs O&M services. 

Red flag: Documentation delivered months after COD, or no plan for who operates the plant on day one. 

Red Flags That Should Move a Bidder Down Your Shortlist 

How Prismecs Answers These Questions 

We ask owners to hold every bidder to the standard above, so here is how we answer the questions that matter most. Every project below is published on our projects page; owner references are available on request. 

Frequently Asked Questions  

What is the difference between EPC and EPCM? 

Under EPC, the contractor delivers the finished plant and carries most cost and schedule risk. Under EPCM, the contractor manages engineering, procurement and construction for the owner, while the owner holds the trade contracts and more of the risk. 

How many EPC bids should an owner compare? 

In typical practice, owners shortlist three to five prequalified bidders. Fewer limits competition; more stretches evaluation without improving the outcome. 

What are liquidated damages in an EPC contract? 

Liquidated damages are pre-agreed sums the contractor pays if it misses the guaranteed completion date or performance levels. In many EPC contracts, they are the owner's sole remedy for delay, so the rate and cap must reflect real lost revenue. 

What is a typical cap on liquidated damages? 

Caps vary by project and lender, but delay and performance LDs are usually capped separately, each as a percentage of the contract price, with an overall liability cap above them. Test any cap against your actual revenue at risk. 

What is the FIDIC Silver Book? 

The FIDIC Silver Book is the international standard contract for EPC and turnkey projects. It puts most design and site risk on the contractor, which is why bids under it often carry a higher risk premium than under the Yellow Book. 

Who guarantees performance when the owner buys the turbines? 

That depends on the "wrap." Either the EPC contractor takes over the equipment contract and guarantees the whole plant, or the contract splits guarantees between the OEM and EPC. Settle this before signing (see question 10). 

Do I need an owner's engineer on an EPC project? 

For large or complex plants, an independent owner's engineer reviews designs, monitors progress, witnesses' tests and protects the owner's interests, especially where in-house technical staff are limited. 

Two Ways to Work with Prismecs 

The right EPC contractor is the one whose answers hold up under these 25 questions, not the one with the lowest number on the cover page. 

1. Invite Prismecs to bid. If you are preparing an RFP for a gas turbine, reciprocating engine, BESS or hybrid plant, we will answer all 25 questions in writing with our proposal. Request an EPC bid or explore EPCM delivery. 

2. Use Prismecs as your owner's engineer. Comparing bids from other contractors? On projects where we are not bidding, our owner's engineering team can review proposals, score them against this checklist and witness tests on your behalf. We will not do both on the same project, and we will tell you up front. 

Talk to a power expert today: 1 (888) 774 7632.