Type A rcd . EICR coding ? etc

Hi Graham


Figure A53.1 shows waveforms which may cause some RCDs difficulties. We discussed those at length above. However, that was not the question I asked which was (written more clearly perhaps) "How can any credible fault produce those waveforms, and if it can, will it operate various types of RCD?" which is very different. I can always say "We need to provide additional protection of the highest level for safety" but that is not the correct answer at all, although it smacks of the usual British Gold plating of any possible regulation or even idea. I am interested in Credible faults that could occur, and once one is established, how often could it happen, in other words, the normal risk assessment criterion. It is unacceptable to expect to make everything completely zero risk, although some like to try and do so, particularly when it costs them nothing or worse when it makes them a profit!


In this boiler case, it is very difficult to imagine a fault which could require additional protection of the boiler or how a credible fault would need a type A RCD. Two unanswered questions, both of which need answers before I can decide on the additional protection measures needed. The instructions give no help at all. If I fit additional protection to protect the wiring, a type AC RCD is exactly what is needed, so why fit a type A, which seems to be mandated by these instructions? If we lose type ACs at some point (which seems likely), what should an EICR say, code C2 perhaps, just in case there could be some fault which causes a type AC to fail?


I am sure that many of you have given instructions to others at work. It is usually found that some explanation is a good idea, as otherwise the intention of the instruction is lost, and the result may well be a disaster. The Army certainly has!


Kind regards

David

Hi Graham


Figure A53.1 shows waveforms which may cause some RCDs difficulties. We discussed those at length above. However, that was not the question I asked which was (written more clearly perhaps) "How can any credible fault produce those waveforms, and if it can, will it operate various types of RCD?" which is very different. I can always say "We need to provide additional protection of the highest level for safety" but that is not the correct answer at all, although it smacks of the usual British Gold plating of any possible regulation or even idea. I am interested in Credible faults that could occur, and once one is established, how often could it happen, in other words, the normal risk assessment criterion. It is unacceptable to expect to make everything completely zero risk, although some like to try and do so, particularly when it costs them nothing or worse when it makes them a profit!


In this boiler case, it is very difficult to imagine a fault which could require additional protection of the boiler or how a credible fault would need a type A RCD. Two unanswered questions, both of which need answers before I can decide on the additional protection measures needed. The instructions give no help at all. If I fit additional protection to protect the wiring, a type AC RCD is exactly what is needed, so why fit a type A, which seems to be mandated by these instructions? If we lose type ACs at some point (which seems likely), what should an EICR say, code C2 perhaps, just in case there could be some fault which causes a type AC to fail?


I am sure that many of you have given instructions to others at work. It is usually found that some explanation is a good idea, as otherwise the intention of the instruction is lost, and the result may well be a disaster. The Army certainly has!


Kind regards

David