V O E L C B and C O E L C B

[westie101]

Were they not also prone, or at least known, to trip due to nearby lightning strikes, particularly with overhead TT supplies

It is not unknown for modern RCDs to do that

 

[JohnW2]

Were they not also prone, or at least known, to trip due to nearby lightning strikes, particularly with overhead TT supplies

It is not unknown for modern RCDs to do that

You just beat me to it! Our RCDs used to do that a lot - alhough it's become far less common in recent times, quite possibly becuase most of the supply in my village (although not mine) has been moved from overhead to underground - might be a co-incidence, but seems to be a credible story. A few years ago, one could almost guarantee that one of the (many) RCDs in my place would trip whenever there was lighting about!

Kind Regards, John.

 

[bernardgreen]

From a practical viewpoint, the only cases of significant voltages being present on CPCs is following the loss of neutral/earth on a single phase service

We had a very bad situation with the DNO supplied "earth" bouncing all over the place following a fault in the cable supplying this area.

A fault under the High St shorted out two phases which tripped the substation breaker. As a rapid "restore" until the road could be opened up the two phases involved were linked at the substation and fed from the same phase. The phase unbalance (66 % on phase A and 33% on phase B) made the neutral current far from zero and tens of volts were on the "earth", Phase to neutrals went as low as 180 at times. We are at the far end of the High St cable which becomes a pole route before it reachs us. We were lucky to be fed from the pole that is the isolation point between two areas and we were soon patched to the other side. People in the High St were asked to use as little power as possible until the cable was repaired.