The 1882-6028448-ND sensor may have labels on both sides that appear to conflict at first glance. One side of the part might show a voltage range of 12-24VDC, the other 24VDC, while the datasheet lists 10-30VDC. So, which one is correct? The short answer: Technically, all of them.
So what’s going on here?
Each rating reflects a different context: nominal voltage, regulatory labeling, and an operational range. Let’s break down what each rating actually means.
Nominal Voltage vs. UL Recognition vs. Datasheet
Nominal Rating
It isn’t uncommon for manufacturers to list a nominal voltage rating on their parts. 24VDC may have been the “initial voltage” that they considered “ideal” for testing purposes. However, many companies may not mention that in the datasheet and just print it on the part without context.
UL Rating
The other kind of label you may see on this kind of sensor is tied to the UL Standard that the manufacturer tested it for. The part in question is currently registered with UL. The full file number is NRKH.E191603 found on page 3 of the datasheet. If you look this up in the UL Product IQ, you can find out more information about the control number (or category code) by clicking on the resources link on the left-hand side that says “Guide Info (NRKH).” You may need to create an account to access this, however, this particular info guide should be free to all users.
The following information is publicly available from UL and can be shared.
UL’s Guide Info (NRKH) note under the Product Markings section says:
“The devices are marked with electrical ratings. At least one rating is marked on the product and additional ratings may be marked on an instruction sheet shipped with the device.”
This means manufacturers have flexibility in how they present ratings, and some may only appear in documentation rather than on the device itself. It is even possible to have different ratings printed because UL Standards, like UL-508A for machine panels, often require more conservative ratings. For example, 508A specifies the use of UL Recognized control relays based on motor current and voltage. These standards are typically designed around “worst-case scenario” testing to ensure a high level of safety and reliability.
Datasheet Rating
The datasheet rating often shows the full operational voltage rating that the manufacturer tested across. This value tends to be wider than the UL Recognized rating.
A common question is whether it’s acceptable to use a part based on its datasheet rating alone. This often stems from confusion about UL’s role. UL is a third-party testing organization, not a governmental agency. However, the U.S. National Electric Code (NEC) does require components used in certain applications to be certified by a Nationally Recognized Testing Laboratory (NRTL), such as UL.
For commercial or industrial manufacturing, NEC compliance may not always apply, but it’s still important to understand the implications.
Another misconception is that using a part outside its UL-tested range is inherently unsafe. In reality, manufacturers often test components well beyond UL requirements. Exceeding the UL rating doesn’t mean the part will fail, it simply means it’s no longer operating within the certified safety envelope. If you’re concerned, consider adding redundant safety measures to protect against overvoltage or other risks. This forum post may help clarify UL a little further.
Conclusion
Apparent contradictions in voltage ratings often stem from different labeling standards: nominal, regulatory, and operational. When in doubt, start with the datasheet, then consider the context of other markings. Conflicting labels don’t necessarily mean a defective part; they just reflect different priorities in testing and certification.