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.
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