Counterfeit industrial components are not a rumour. Contactors, circuit breakers, PLC modules, sensors and drive keypads are all copied, and the copies have improved enough that the obvious tells — misspelt logos, glue on the case, a plate printed at the wrong angle — now catch only the worst of them. A dated example: in January 2026 New Hampshire’s Department of Environmental Services warned water utilities about counterfeit Rockwell PLCs bought through unauthorised online resellers. In the case it describes, the fake surfaced only when a routine firmware update failed and the manufacturer’s serial-number check flagged the unit.
The defence that works is a routine applied to every incoming part from a source you have not bought from before, not a single clever test.
Before it ships
Most counterfeits are caught by paperwork, not by inspection.
- Ask where the unit came from. A good supplier can tell you: cleared stock from a named distributor, a decommissioned line, a repair inventory. “Our warehouse” is not an answer. Manufacturers give the same advice from their side: Rockwell’s gray-market and counterfeit page recommends buying from authorised distributors and lets owners register a new product to check it against Rockwell’s production records.
- Ask for photographs of the actual unit, not a catalogue image — the rating plate readable, the packaging, and the connector side. Compare the article number and functional version against what you ordered.
- Compare the price to the market. A part that is 70 % below every other offer is telling you something. It may be a genuine clearance; it is worth asking which.
- Prefer a supplier with a verified company record, and read what other buyers said. On this site, verification means an admin reviewed the company’s registration extract or VAT certificate — it is a statement about the company, not about a specific unit. The trust page sets out what verification covers.
Is it safe to buy a PLC on eBay?
It can be, but treat every “new” listing as unverified. Rockwell’s counterfeit page says that all “new” Rockwell products on eBay, Amazon or Alibaba are gray market and possibly counterfeit, and that its warranty and software licences apply only to products from an authorised source. A used unit from a seller who answers questions is a smaller, manageable risk.
The red flags, as an automation repairer’s eBay buyer’s guide, updated in March 2026, lists them:
- Location mismatch. The listing names one country and the parcel ships from another.
- A “new” price far below the market, often from a seller with apparently endless stock of the same module.
- Hidden serial plates. Blurred in the photos, scratched off or covered by a sticker, or stock images instead of the actual unit.
- Dates that cannot be right. A “new” box dated after the manufacturer discontinued the part, or misspelt labels.
- Slogans instead of facts. “Sealed goods”, “US stock” and long handling times that suggest drop-shipping.
Packaging
Genuine industrial packaging is boring and consistent. Look for:
- A label with the article number, a batch or serial number, and a date code that is plausible for the part’s production run.
- Consistent print quality: the same font, the same shade of ink, the same barcode symbology as other units of the same family you already own.
- Anti-static bags that are actually anti-static (pink or metallised, not clear polythene) for electronics.
- No mixed branding inside one box.
An original part in a plain box is normal on the surplus market — stock is repacked all the time. A copied label is not normal, and that is what you are looking for.
The rating plate and the case
Put the new unit next to a known-genuine one of the same type. Almost everything a counterfeiter gets wrong is visible in a side-by-side comparison:
- Plate text. Laser-etched or high-quality printed on genuine parts; often slightly blurred, thicker or subtly different in kerning on copies.
- Certification marks. CE, UL, CSA, TÜV, ATEX marks should be crisp and correctly proportioned. A UL mark without a file number, or a certification the family never held, is decisive.
- Serial and date codes. Present, plausible and consistent between the plate, the label and any internal marking.
- Moulding. Look at the seams, the ejector-pin marks and the screw bosses. Injection tooling is expensive to copy well; counterfeits often have softer detail and slightly different textures.
- Weight. Copies are frequently lighter. A contactor with less copper in the coil and less silver in the contacts weighs less, and a kitchen scale will tell you.
Opening it up
Where the part allows it without voiding a warranty, the inside is where the differences are largest.
- Contactors and breakers: look at the contact tips. Genuine silver-alloy tips are substantial and evenly formed. Check the coil’s wire gauge and insulation quality.
- PLC modules and drives: the PCB should be cleanly manufactured with proper solder joints, no hand-rework on a supposedly new unit, and branded components from the manufacturers the original used. A board with no silkscreen revision, or with obviously mixed component brands, is a warning.
- Connectors: plating quality and retention force are hard to fake cheaply.
Behaviour
Finally, test it where you can:
- Coil pick-up and drop-out voltage on a contactor, against the datasheet.
- Contact resistance, if you have a micro-ohmmeter.
- A drive under load rather than at no load — counterfeit and failed-refurbished power stages usually pass a no-load spin.
- For a PLC module, a full I/O channel test rather than a power-up LED check.
- For a PLC or drive, a firmware update and the manufacturer’s serial-number check where one exists. Copies often refuse a genuine firmware update.
What should I do if I suspect a counterfeit part?
Stop, photograph everything before you disassemble further, and contact the supplier with the specifics. A legitimate supplier who was themselves supplied a fake will want to know, and will usually take it back immediately. If they will not, report it — on this marketplace that is the report button on the offer and the supplier page, and a substantiated counterfeit report is grounds for removal.
Do not install it “just for now”. A counterfeit contactor that welds, or a copied breaker that does not clear a fault, is a safety failure, not a commercial one. For anything in a safety chain, the safety parts guide covers the documents to insist on, and the warranty guide covers what a supplier warranty does and does not include.
Sources
Links checked on 13 October 2026.
- Rockwell Automation: Gray Market and Counterfeit Products: what Rockwell counts as counterfeit, its authorised-distributor advice and product registration.
- New Hampshire Department of Environmental Services: Advisory Bulletin, Counterfeit PLCs, issued 29 January 2026: indicators of counterfeit PLCs and the firmware-update case quoted above.
- NJT Automation: How to spot fake Allen-Bradley parts on eBay, updated March 2026: the eBay red flags summarised above.