In this guide
When a part is hard to find, the word describing its condition matters as much as the price. These terms are used across the trade, but they are not standardised, so treat them as a starting point and get the details in writing.
The terms
| Term | What it should mean | What to ask |
|---|---|---|
| New | Unused, from the manufacturer or its authorised channel, in original packaging | Where it was bought, and whether the packaging is sealed |
| New old stock | Unused, from original production, sometimes years old | Date code, version and how it was stored |
| Surplus | Unused excess from a plant or a distributor | Where it came from and why it is surplus |
| Refurbished | Used, then cleaned, tested and repaired where needed | What was tested, what was replaced and what warranty applies |
| Used | Taken out of service, and possibly untested | Whether it was tested at all, and the return terms |
Why condition matters
- Ageing: unused parts still age. Electrolytic capacitors can dry out and backup batteries go flat, even in storage
- Version: a part of the right order number can carry a hardware or firmware version that does not suit your system
- Wear: used parts have run hours that you cannot see from the outside
- Origin: the less clear where a part came from, the higher the risk that it is not what the label says
What belongs on every quote
- The condition, using one of the terms above
- The source, in plain words
- The hardware and firmware version where it can be read
- The warranty and returns terms
- The lead time
Safety-related parts
For safety relays, safety controllers and safety-rated sensors, buy only from a source you can trust fully and keep the paperwork. A part that works on the bench is not the same as a part certified for its safety function.
When it arrives
- Compare the label, finish and markings against a known good unit
- Check the version against what your system needs
- Test it where practical before it goes into the machine
- Keep the packaging and documents
If you are comparing quotes, ask each supplier for the same five details. A quote that cannot state its condition and source is not ready to compare.