UL listing for a product with UL-listed PSU? - Page 1
Forum section: electronics / projects

author: Bandit-Technical
author_rank: Contributor
timestamp: September 03, 2015, 01:40:46 pm
content: For example there is some product which has enclosure, and some PCBs inside. If someone plans to use the UL-listed PC PSU unit inside that product, does he still need to have the whole product UL listed or not?

author: AndyC_772
author_rank: Super Contributor
timestamp: September 03, 2015, 01:49:41 pm
content: Depends on whether or not UL listing is actually a requirement where the product is being sold.If it does need a UL mark, then the fact that the PSU is already listed doesn't exempt any other part of the system from being tested - but it does considerably reduce the cost and extent of the testing that'll be required on the complete system.

author: Bandit-Technical
author_rank: Contributor
timestamp: September 03, 2015, 01:57:03 pm
content: Quote from: AndyC_772 on September 03, 2015, 01:49:41 pmWell, not really a requirement, lets say the product is basically some measurement tool to be used in lab or home. (i.e. its not some fire or security or alarm equipment or something required by insurance companies).How would it be in that case?

author: metri
author_rank: Contributor
timestamp: September 03, 2015, 03:32:00 pm
content: As previously mentioned it would reduce cost of certification and time. Is the power supply internal to the product? If the power supply is internal, you would definitely need to certify the entire product. You would be unable to affix a UL label to the outside of the product as it belongs to the power supply only, that is inside the product and if it plugs in, it needs a label. If you were to use an external class 2 low voltage power supply attached externally through a connector to your device, there is a chance it would not need seperate certification. You would have to see what specific UL code may apply to your product. I have experience certifying low voltage power supplies, and LED lighting products & systems, but not with test equipment specifically so I'm not sure which UL code applies for you. More information on your device is needed for a concrete answer.

author: Bandit-Technical
author_rank: Contributor
timestamp: September 03, 2015, 04:56:52 pm
content: external certified PSU connected to my "box" with cable looks like attractive solution of course. For that case, I assume it would not matter what my device is, correct? (of course, given the fact that the UL listing is not specifically required for my device).In other words, its all about delivering power to my device (or "box" or product or whatever), and that power has to come from wall socket, so if I use certified external PSU which connects to my device with cable, I effectively avoid UL?

author: dino
author_rank: Contributor
timestamp: September 03, 2015, 05:31:29 pm
content: You only reduce UL test duration and complexity.In any case, in order to put a UL stamp on the device, you need to go to a UL lab, which will test the device (electrical, mechanical, documentation, etc).The UL stamp indicates that a certification body checked your device and found that it is safe to use.

author: AndyC_772
author_rank: Super Contributor
timestamp: September 03, 2015, 05:32:24 pm
content: Give me a UL listed power supply, and I'll find a way to start a fire with it.You can't claim your entire system of (PSU + box) is UL listed if only the power supply actually is.

author: Bandit-Technical
author_rank: Contributor
timestamp: September 03, 2015, 05:47:05 pm
content: i think there is miss communication, l will re-state my points:I do not make product which *needs* UL listing logo, I do not want to put UL Listing on my product.What I want is, for example, to sell a product which needs to be powered from wall. That's it. I do not intend to put UL logo on a product or get involved into all testing, so, in order to avoid all that, but at the same time being able to legally sell the product which is getting powered from wall socket (through PSU). Is it OK to just include an external UL Listed PSU when shipping my product? This way I do not have to engage in expensive UL testing procedure. Of course I am not going to put any UL Logo anywhere on my product itself. My product will be just in a package box with another UL Listed PSU which I buy and re-sell when selling my product.This way, the whole responsibility as well as testing and UL certification is on someone who made PSU.How does it sound now?

author: AndyC_772
author_rank: Super Contributor
timestamp: September 03, 2015, 06:20:16 pm
content: It sounds as though your question boils down to "what regulatory requirements apply to my product?". This depends on what the product is, and where in the world you plan to sell it.If, for example, you're planning to sell it in the EU, then it would require a CE mark. The fact that your PSU is UL listed is a small bonus, but from a legal point of view, irrelevant.

author: john_p_wi
author_rank: Regular Contributor
timestamp: September 04, 2015, 01:30:07 am
content: It doesn't matter if the power supply is external or internal if the device has the equivalent of 15 watts or greater in the enclosure...There will need to be flammability, impact, the "finger" opening, markings etc to be evaluated that will run tens of thousand dollars.

author: nctnico
author_rank: Super Contributor
timestamp: September 04, 2015, 01:38:33 am
content: I think he is asking whether a wall-wart of lump-in-chord power supply can be seen as a part of his product or not. If it can be disconnected the answer is: I don't think so. It is a common way of getting around expensive testing when a piece of equipment needs to be powered from mains. IOW: sell 2 seperate products in one box: a power supply (bought as a compliant unit) and your own product.

author: metri
author_rank: Contributor
timestamp: September 04, 2015, 03:05:03 am
content: I think there is a lot of conjecture going on.It's free to get a quote from ETL or UL on what they would suggest you certify the device for. That can at least remove some of the research into what you need to do. I've had pleasant'ish dealings with ETL, and UL is... a nice logo to have.If your power supply is class 2, note the stipulation, ie. low voltage protected from high voltage, and your power supply connects externally with a cord, you MAY not require further certification for your device.Quote from: john_p_wi on September 04, 2015, 01:30:07 amMight not be a completely correct statement. Low voltage devices don't have enclosure opening requirements as they are considered safe to be opened. Non class 2 powered devices do. There is a difference between an internally connected power supply and externally. There is also a difference if you product is certified for use with any class 2 power supply or is certified as a system. There are so many variables, without all the details of the project, it's all speculation as to what you can and can't do. I can say for certain, keeping the device low voltage will make the product easier to certify if that is needed and cheaper.You can get a free quote (it's the only thing they will ever give you for free) and as them all the questions you want. Then you will know definitively.Be very careful taking third party advice on regulations. They are country and sometimes even state specific. The consequences, in the way of liability, for not conforming can be scary.