Hi Rick. You wrote: <1. Can US fuses be used to meet the regularly requirement of Europe? 2. Are 5mm fuses REQUIRED to meet world wide applications? If so must they also be used in secondary circuits? 3. It has been suggested that both fuses could be put in series. Is this a solution?>
1. Yes, as long as they are suitable for the supply to which they are connected. i.e. they must be rated to break 230V a.c. and they must be rated for the maximum prospective fault current. So if it's powered from a (say) 64A MCB, the maximum fault current may be 8kA. The fuse must break this without bursting etc. These are called HRC over here (high rupture current) and are normally ceramic bodies with silica sand infill. Not many 20mm x 5mm fuses are rated for 230V, particularly at high fault currents. If the supply is from a low current MCB or fuse, e.g. in a panel distribution system, then you must have good discrimination wrt the fuse/mcb above. If this is so then 20 x 5 fuses will probably be OK, but as a rule any fuse cionnected to a non current-limited supply (such as a transformer secondary) should be a HRC type. 2. 20mm x 5mm fuses are invariably ok for use in secondary circuits, voltages being checked of course. 5mm fuses don't usually meet Fault Current/ voltage requirements. 3. Yes, but a bit daft. Can you go to 1.25" fuses and be done with it? Fuses that size meet the requirements of both sides of the wet divide. That's a tuppence worth, maybe... Chris Dupres Surrey, UK.
