Hi Brian, I see most of the return postings have focused on the UK, which has a terminated neutral system. There are several installations especially in the US, where the power could be derived from a delta, or unterminated neutral system. I believe in this case, overcurrent protection is required on both lines. In addition, the 2 pole circuit breaker method provides a suitable 2 pole disconnect.
Good Luck, Ray Russell [email protected] -----Original Message----- From: brian_kunde [mailto:[email protected]] Sent: Friday, October 06, 2000 12:32 PM To: emc-pstc Subject: Overcurrent Protection: One or Both Sides? The issue of designing in Overcurrent Protection on one side or both sides of the AC mains keeps coming up. We deal in Laboratory Equipment so the EN 61010-1 is the standard we use. I'm not sure what EN60950 would say on the subject. The only area I have found that deals with this question is a NOTE in section 9.6 of EN61010-1 which says, "Overcurrent protection devices (e.g. fuses) should preferably be fitted in all supply conductors." This seems "GRAY" to me and I get beat up on it all the time. I feel that overcurrent protection should be on all current carrying conductors. With a 230V~ product you never know where in the world the product will be shipped, if the AC Main has a grounded neutral, or if the receptacle is polarized. So, I feel you never know for sure which line or if both lines will be "HOT" in reference to Earth ground. If my thinking is correct, shouldn't ALL 230V~ products have overcurrent protection on both sides of the line? I would think so, but I see products everyday that only have ONE side of the line fused. My superiors feel that if others can get away with it, why can't we. Why add the extra cost of double pole breakers or double fuse holders if it is not necessary? Am I being too cautious or do I have a point? Thank you for your support and advice. Brian Kunde LECO Corp. ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
