This is in response to the product marketability question. It is true that a PC buyer for a private application is most likely not concerned with safety approvals status for a card assembly for his/her PC. But if the PC card assembly company intents to pursue large volume sales to OEM and/or other companies, it is not unusual for that large volume buyer to impose safety certification requirements as a condition for the sale.
George Seminsky Manager, Hardware System & Compliance Nuera Communications Ph 619 625 9220 ext 1248 Fax 619 625 2422 From: Rich Nute <[email protected]>, on 5/30/97 8:07 AM: Hi Chris: In answer to your questions about a PWB board for user-installation in a personal computer (PC): > 1) Is it a given that all PCs meet UL1950 or IEC 950 directly or > indirectly? PCs marked with any of the safety certification house certification marks comply with an IEC 950 clone. PCs marked with the CE mark comply with EN 60950. PCs not marked with either mark should not be assumed to comply with IEC 950. I understand that a PC could be assembled from readily available parts, in which case it would not bear a suitable certification mark, and should not be assumed to comply with IEC 950. > 2) Would my card need to meet UL1950 for the USA market? Yes and no. If you were to supply the complete PC with your card installed, then your card, as a part of the PC would need to meet UL requirements for the PC to bear the UL mark. However, if you supply the card after the PC is sold, and for installation by the user, then there is no "enforcement" as to whether or not the card meets UL requirements. UL has a certification program for such cards. Not many card manufacturers use this program. > If no - is there any perceived market value by meeting 1950 for > this card? Is there any percieved market value for ANY safety certification mark? PC buyers do not select the PC on the basis of whether or not a safety certification mark is on the product, let alone which one! > 3) Would my card need to meet EN60950 (IEC 950) to satisfy the CE > mark LVD? There are two issues: 1) Are components permitted to use the CE mark? The rule is no. However, some manufacturers have chosen to mark components with the CE mark. (Keep in mind that use of the CE mark indicates compliance with ALL of the applicable directives, including the EMC directive.) 2) Is the card subject to the LVD? No. The LVD does not apply to products where the voltage does not exceed 50 V dc or rms. > 4) Is there a market expectation to see EN60950 on a PC card in > Europe? Having said all this, I want to offer some comments on the true safety of the card. First, to protect against fire, I advise you to use a fuse in the 12 V supply line. While the 12-volt supply in a PC is usually a wimpy supply, you can't count on it always being a wimpy supply. Consequently, the only way you can provide positive protection against your card overheating and causing a fire is to provide overcurrent protection as a part of your card. Consider that your card COULD be connected to a supply equivalent to your car battery! Second, the isolation transformer and spacings on the board should be capable of withstanding a power cross occuring on the twisted pair signal wires (external to the card and PC). You should seriously consider complying with the requirements of IEC 950, Clause 6. While these requirements apply to telephone connections, any set of wires within a building are capable of a power cross. >From your description of the product, I doubt that you would need to do anything but comply with the dielectric strength requirements. Best regards from San Diego, Rich
