Check the BOM against the PO before the wrong part is ordered

The purchase order is where a quote becomes real money. Until then, a wrong quantity or a superseded part number is a spreadsheet error. After release it is freight, restocking fees, idle labour or a missed ship date. For a custom panel shop, which buys dozens of different components for each job, the last check before ordering is one of the cheapest places in the business to catch mistakes. This guide sets out what to check, how to code lines by supply risk, and how to keep quotes honest when lead times and costs are moving.

Why the check matters: errors travel

OpenBOM, a BOM management vendor, groups common bill of materials errors into quantity mistakes, missing components, costing that is done too late, requirements that engineering, production and procurement do not share, and regulatory requirements lost between engineering and purchasing. It notes that late-discovered errors are expensive because the design is complete and parts are already ordered. A purchasing check is the point at which most of those errors can still be fixed for the price of an email. Research on engineer-to-order companies makes a related point: engineering changes spread into purchasing and production, but those teams are often brought in only after approval. Checking the BOM against the order at release is the habit that closes that gap.

The pre-release checklist

Lead times: what the published figures show, and what they do not

Lead times are the part of the check that has changed most. Industrial Monitor Direct, a vendor knowledge base, publishes field-reported ranges for control components, with the caveat that they are not manufacturer ship dates and should be confirmed with an authorised distributor at the time of the RFQ. Its table includes, for example, 30 to 52 weeks for some PowerFlex drives, 20 to 40 weeks for Siemens S7-1200 CPUs, 20 to 40 weeks for ABB ACS580 and ACS880 drives, 16 to 26 weeks for B-rated miniature circuit breakers, 12 to 20 weeks for 4PDT relay sockets and 8 to 16 weeks for Mitsubishi MELSEC. The article reflects conditions around 2021 to 2023, so read the figures as an illustration of how wide the spread can be between components in a single panel, not as current quotes.

The wider picture in 2026 is also unsettled. Frontier Electric Supply, an electrical distributor, reported in a 2026 industry briefing that top-category semiconductor lead times reached 40 weeks in March 2026, up from 20 to 25 weeks through most of 2025, and that tariffs and logistics had pushed landed costs on some products sharply higher, giving as examples an estimated 15 to 30 percent increase on motor starters, advanced protection relays and industrial UPS systems, depending on where the semiconductors and assemblies originate. These are a distributor's estimates and will vary by product and source, but they point in a consistent direction: prices and lead times can move between quote and order, so a quote needs a validity period and a repricing policy that reflect that.

Code every BOM line by supply risk

The Industrial Monitor Direct guide recommends tagging each BOM line A to D by number of sources and lead time, with D covering lines of 26 weeks or more or on allocation. The exact scheme matters less than having one. A simple version looks like this.

The same guide advises getting onto a manufacturer's allocation list with a forecast rather than relying on spot purchases, holding accounts with at least two authorised distributors per major brand, and keeping rolling safety stock on the most exposed lines. It also advises locking panel dimensions to a product-family envelope so that a substitute can drop in without redesign, and checking date codes, sealed packaging and traceability on allocated or grey-market parts. Safety components are a special case: it states that substituting them is not permitted under functional safety standards without re-validation.

Substitutes are engineering work

It is tempting to see a substitute controller as a purchasing decision: same function, different brand, shorter lead time. The reality is different. The same guide estimates that moving to a different PLC platform can need a full re-implementation of 40 to 80 engineering hours per controller, and it recommends pre-qualifying one substitute for every PLC, drive, HMI and safety component and documenting it before ordering the original. That turns a delay into a planned alternative with a known cost, and it should be written into the quote as an assumption. Where the panel carries a listing mark, a substitution also has to be reflected in the documentation, as covered in our UL 508A documentation checklist.

Set re-check triggers for open quotes

A quote is a snapshot, and open quotes go stale while customers decide. Rather than reviewing every open quote on a calendar, set triggers that tell you which ones need a second look: a price change on any line above a threshold you choose, a lead-time change on a long-lead line, or a quote approaching the end of its validity period. It helps to know what a price move is worth. As a worked illustration, suppose components are 40 percent of a job's cost and component prices rise 5 percent. Total cost rises 2 percent. On a job priced at a 25 percent gross margin, that cuts profit by about 6 percent, so a modest-looking price move has a bigger effect on profit than on cost. Calibrate your own thresholds from your typical margin and material share, and review them when conditions change.

Keep the quote honest

A purchasing check protects margin only if the quote reflects what it finds. When long-lead lines are identified at quoting, the quote should say so: a shorter validity period, a stated right to reprice if supplier prices move, named alternates and a delivery date conditional on component availability. Our control panel quoting checklist shows where those lines go in the quote, and our cost estimating guide shows how to price the risk.

When drawings change after a purchase order is out, the position depends on how quickly the change reaches purchasing. The process in our engineering change order guide is built to do exactly that.

Where automation fits

The BOM-to-order check is a comparison task: thousands of fields, mostly matching, a handful not. It is slow and dull for a person and quick for software, provided a person reviews the exceptions. Our purchasing checks workflow compares the BOM with the purchase order before parts are ordered and lists the mismatches for your buyer to resolve. The companion price and lead-time alerts flag open quotes whose cost or lead time has moved so that your estimator can decide whether to re-quote. Both are planned workflows within the Steady Rabbit AI practice, shaped with our first design partners.