------Question for D3D-123 Please Put your question below------
Can this switch be used with 12VDC power? The specs only list AC ratings.
Link to switch. I plan on using this to turn on ~6in of LED light strip that has a power rating of 3w/ft (1.5w divided by 12v = 0.125A).
Hi kevin5,
Welcome to the TechForum.
Well, the answer is “maybe”, but it is not well defined. I found this FAQ on Omron’s website regarding applying DC to an AC-rated switch. It is not very definitive.
From the datasheet, they do mention a “minimum applicable load” and specify this as 1mA at 5Vdc. Below this, the contacts will tend to fowl over time due to a lack of cleaning as the current is removed, and fail prematurely. So they do, at least, mention testing with a DC load.
My gut feeling is that your load of 12Vdc at 125mA would probably be fine since it’s only 1/4 of the 250Vac rating, though it may not last the full 50,000 operations specified in the datasheet. However, if the inrush current were much more than 125mA, that may reduce life significantly.
If this is for a personal project, I wouldn’t worry much about it, as it’s likely to last quite a while, assuming it isn’t constantly being cycled. However, if this were for a commercially sold product, I would advise doing thorough testing with a real load, and/or contact Omron to discuss your application and the suitability of this switch.
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Thanks, David. Very informative. We are looking for a plunger switch like this to turn on lights when a cabinet door is opened. This is to be used in campervan cabinets, hence the 12VDC requirement. We will test out this switch, see how long it lasts, and decide if it’s okay for our application.
Do you know of any other ON-MOM switches that are DC rated? Preferably panel mount like this one? I had trouble finding such a switch under Limit Switches and Push Button Switches.
Thanks again!
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I’ve narrowed down some options that include 500mA DC to 5A DC (some say AC/DC, but that will work too). To add on to David’s response, Omron seems to have just intended to design that part for AC applications using UL/VDE AC specifications. Many companies sort of have particular use cases. It certainly doesn’t mean you can’t use DC, but like David says, it kind of sits at an “unknown.”
Here is the list of the parts I found: Panel Mount On-Mom Switches
I couldn’t find other ones that snap in though.
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Thank you very much, Kaleb! Huge help
Note that there may be other ways to accomplish this as well, though it may add a bit of complexity to the design.
For instance, one could use a reed switch or a reed switch-based sensor and a magnet to detect whether a door were closed. These typically can’t handle the current you need, but you could use a reed switch to activate the coil of a remotely-located relay.
Reed switch:
Reed switch-based magnetic sensor:
Yep, I got worried about the current rating on those magnetic/reed switches. We’ve seen other builders use those but I wanted something more robust. The irony is the switch I selected may not be that robust! I like this KDS switch as a back up. Slides into a sheet metal part nicely (it appears anyways).
Expanding the selection set to include double-throw devices would tend to offer a lot of additional options, as normally-closed momentary switches tend to be less commonplace. Installers would need to be capable of selecting the correct terminal to connect, but a selection with equivalents available from multiple sources is always preferable for supply chain reasons.
One might also consider a magnetic reed switch sort of device for an application of the sort. Looks like Dave beat me to that idea…
Regarding ratings, these commonly reflect the degree of blessing sought from a standards body, which isn’t quite the same as the capabilities of the device itself. DC is indeed a harsher use case than AC, but dialing back the operational current and voltage ~90% both from the AC ratings is likely to be quite conservative from a practical standpoint.
Regarding reed switches, those tend to be rated somewhat differently; most will have a VA rating, which refers to the maximum product of current and voltage that appears during the switching process. Devices with ratings of ~2VA or higher would be reasonable to consider for the application described.
If one’s interested in testing things for oneself, a panel mount counter sort of device might be useful…
As @rick_1976 stated, some of the higher VA rated reed switches could probably handle your load fairly well. For the lower power versions, one would need to take the output of the reed switch to energize the coil of a relay, which would then actually switch your main load. As I stated, this adds complexity, but it also adds flexibility in terms of form-factors and placement.
Note that the KDS switch is not adequate for directly handling your load, as it is only rated for 0.4VA (only about 33mA at 12V), and as @rick_1976 mentioned, you’ll want to be at least in the 2VA range. It would, however, be a viable option to consider to drive the coil of a remote relay, just like the reed switches mentioned above.
Ah, good catch David. I read that as 0.4A, not 0.4VA. I’ll look at the reed switches again if this Omron switch doesn’t work out. I really appreciate all the help!