I've had some power supplies with no NRTL marks. Definitely lower quality. No solder mask on the PCB and no strain relief for the wiring (tugging on the wires pulls directly on the solder joint). Parts teepeed because of change to design without redesign of the PCB. But this isn't too suprising since any company too cheap to get their products listed or recognized probably cut other corners as well.
Hardwareguy, you made one statement that I find to be backwards. European product approval is MUCH easier than the United States and Canada. In fact, its a joke in comparison. Even Mexico is tougher.
To apply an NRTL mark in the US, you must submit samples for testing to a Nationaly Recognized Test Lab such as UL, Intertek/ETL, CSA, Curtis Straus, MET labs, etc. The NRTL must be authorized as an NRTL by OSHA and operated and audited under ISO 17025 (defining appropriate laboratory procedures). After product approval, the NRTL will make regular visits to your factory to make sure you are still building your product with the appropriate components - the ones that were identified as critical during the initial product evaluation. The safety standard in the US and Canada was adopted from the international IEC version, but adds requirements, sometimes rather significant. For example, Europe does not have a "power cross" test for telecom circuits to ensure safety from fire in the event a tip or ring pair comes into contact with outdoor power lines. Also, in the US a user-accessible exposed SELV (low voltage <60vdc) circuit must remain within SELV limits. In Europe, under fault conditions, it is allowed to jump to the maximum voltage allowed for a telecom circuit.
In Europe you only need to apply the CE mark to get your product to the store shelves. The CE mark means "this product complies with all applicable compliance criteria, and I can supply data to back up this claim". The CE mark is a "self declaration". There is no requirement for third party verification, and no requirement to audit manufacturing facilities. You can apply the CE mark based on design data if that suits you (good luck on that lawsuit).
To me, the no fuse issue would raise an eyebrow, but it does not mean the product "fails UL". Computer power supplies are currently Listed to ANSI/UL 60950-1 and/or CAN/CSA C22.2 No. 60950-1 (themselves a variation of IEC 60950-1). This harmonized safety standard specifies safety under normal operation and under single-fault conditions. As with many standards, there is no specific requirement for a fuse. If failure analysis indicates no fuse is needed, then you don't need one. That said, under single fault conditions, primary to secondary insulation damage is likely to occur if there is no electrical fuse and there is no thermal fuse. But, protection may be provided by other active circuits, or by Listed fuseable wire in the primary circuit...or something else.
OSHA requires use of Listed equipment in the workplace, and your insurance company may fight you on a claim if you have a fire as a result of using non-Listed equipment (that being the whole purpose for creating Underwriters Laboratories). A reputable company that only sells to US/Canadian customers should not be selling non-Listed or CE-only electrical equipment to the general public. You probably won't find this stuff at a North American Walmart or Sears.
Last edited by electech; 06/22/07 02:27 AM.
