Loss of neutral

Nice idea Mike, and under the circumstances I can see your idea may have some merit, however being more worried about "incoming" myself, I should probably not bother. I am sure it is not compliant Graham because it probably is contrary to 531.3.1.202, but also increases the Earth current to a potentially higher level than necessary, therefore touch voltages are probably out of control. Under some circumstances it may make Mike safer, some others perhaps not.


The loss of neutral event is very damaging because the N-Phase voltage can get well beyond the safe operating voltage of electronics for a significant period, (several cycles with mechanical disconnection). The "fastest fuses known to man" can be rated to withstand this kind of event in large and expensive equipment, but in cheaper domestic stuff, which is very price sensitive in component choice, it doesn't happen. I would expect a 100kVA UPS to withstand this kind of event, but probably not the TV or LED lamps. It is very different from the average transient because of the time of fault and the very large energy available. 400V on the 230V supply for a second probably wouldn't affect heating appliances or resistive loads but your iPhone charger might well fail. I suggest that the dictum of PME should be applied, in that it "never happens", except in quite a lot of occasions not reported to the HSE!


Have you reported it Lyle?

Nice idea Mike, and under the circumstances I can see your idea may have some merit, however being more worried about "incoming" myself, I should probably not bother. I am sure it is not compliant Graham because it probably is contrary to 531.3.1.202, but also increases the Earth current to a potentially higher level than necessary, therefore touch voltages are probably out of control. Under some circumstances it may make Mike safer, some others perhaps not.


The loss of neutral event is very damaging because the N-Phase voltage can get well beyond the safe operating voltage of electronics for a significant period, (several cycles with mechanical disconnection). The "fastest fuses known to man" can be rated to withstand this kind of event in large and expensive equipment, but in cheaper domestic stuff, which is very price sensitive in component choice, it doesn't happen. I would expect a 100kVA UPS to withstand this kind of event, but probably not the TV or LED lamps. It is very different from the average transient because of the time of fault and the very large energy available. 400V on the 230V supply for a second probably wouldn't affect heating appliances or resistive loads but your iPhone charger might well fail. I suggest that the dictum of PME should be applied, in that it "never happens", except in quite a lot of occasions not reported to the HSE!


Have you reported it Lyle?