Mains powered plug-in enclosure

Hello, I'm working on a mains powered design and am having difficulties finding a wall plugin 'shell' to use for my design. I would like to place a custom PCB inside the wall plugin (picture a cell phone charger, and cut the cord) and have my circuit mains powered. My circuit will require around 300mA at 3.3VDC. Any suggestions? Would something like this have to go through UL certs if I find the ACtoDC converter in an enclosure that is already UL certified?

Thank you in advance!

Reply to
teaks
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U/L certification is the main reason why you have so many wall warts behind your PC. Designing and getting a mains powered device NRTL tested will gobble up a huge part of your potential profits. It is easier for a designer to start with low voltage DC from an already listed supply.

Reply to
gfretwell

If you use a UL listed low voltage power supply, and your device is in a separate enclosure so it only sees low voltage, then you will probably not need UL listing on your device. However, if you mount your circuit board inside the plug-in housing, you will need to get the finished product UL listed. Even if you use a listed converter, as soon as you open it and install your components you void the previous listing. Of course, not knowing what your product is, I should point out that there may still be other agency approvals necessary.

Ben Miller

Reply to
Ben Miller

When will you guys in the USA learn that you do not need a UL approval any more for the USA, what you need is a NRTL approval, where the product has been tested to UL standard, but not a UL approval. We moved away from this in Europe years ago, we now only look for an approval from a European Nationally recognised approval body. For example if you wanted TUV to approve a piece of IT equipment, they would look for components approvals from a European Approval Body, this could be BSI, DEMKO, NF, VDE etc. This makes life much easier when you are designing a new product and need to source components.

BillB

Reply to
billb

True, to be accurate it can have any NRTL mark, such as ETL, but that will still imply the same requirements for the product. Nothing changes with regard to the OP query, other than the name of the lab.

Ben Miller

Reply to
Ben Miller

I'm glad to hear you agree, but everyone seems to only think in terms of a UL approval. In the UK clients complain about the service they get from UL, but still keep going back for more. It's time more people realised that any of the NRTL can issue approval as long as they are accredited for the standard involved.

Some clients in the UK come to us for a CB test report and certificate and then apply for a UL approval using our CB certificate and report, they tell me it reduces the time to get an approval from UL. We could issue a NRTL approval in the USA for them, without the extra cost of a CB report and certificate and in less than half the time it will take them to get a UL approval. When we ask them why they keep using UL the answer is always their clients in the USA is asking for a UL approval.

BillB

Reply to
billb

Bill That may make sense given the origin of the name "Underwriters Laboratories." The original UL was a loft building in Chicago were an engineer hired by the insurance underwriters for the great Chicago Exposition set up his shop. The fires caused by the inadequate parts being used to install the brand new electric lights for the exposition had killed two of the first due fire companies horses by exhaustion. After the underwriters forced all of the installers to submit samples to their engineer the exposition came off with far fewer problems then the construction phase would have suggested.

There may still be insurance carriers that will only except the UL label. The counterpart in the mutual insurance companies was the factory mutual approval process. UL served the stock companies and FM served the mutual insurers.

The other problem we have here is that UL has become the Kleenex or Zerox of testing laboratories. Their customer may be saying UL when they only mean NRTL listed.

Reply to
Tom Horne, Electrician

Wow, you learn something new every day. I never knew that history. Back in the 70's I used to work a block away from the then UL Chicago headquarters, which was a small multi-story building on the near north side, not far from Navy Pier. The building had winding staircases with brass railings. Perhaps the same building? I called on them often working on our product approvals. They closed that building down years ago. I now work less than a mile from their Northbrook, IL main headquarters. It is just a bit bigger!

Ben Miller

Reply to
Ben Miller

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