It would be useful Graham if you could produce a document showing a manufacturer who has these instructions? Manufacturers do not have to comply with BS7671, which covers fixed wiring installations only. An inverter will remove output on a short to Earth very quickly indeed, as an act of self-preservation, probably within a fraction of a milli-second. In what way does this not comply with BS7671? Verifying this kind of thing is very difficult for a typical Electrician, so you are saying that he may not install this equipment? This is the problem with regulations and standards of all kinds, "features" get added which have no place because "someone" thinks it is either necessary or would be nice, and everyone else nods in a SAGE way and lets it pass. It doesn't matter if the idea comes from Cenelec or elsewhere, if it doesn't make sense to practicality, it shouldn't be there. There are many other examples to be found, there is no shock risk at all from an Earthed motor with properly installed wiring, with whatever mechanical protection suits the environment. This is a case where no additional shock protection should even be mentioned. 419.2 is not necessary at all. It now seems to be thought that the Earth conductor is considered "dangerous" in itself and that all the Earthing and bonding is inadequate unless additional protection is added. This is ridiculous and has no reasonable danger scenario which is improved. Someone may like to make the case of why it is required, preferably generally, and not a motor in the middle of a lake used for swimming with convenient handrails attached. It is fundamentally impossible to fully comply with 419.2 if the inverter is not an appliance, which in my opinion it is, therefore not covered by BS7671 at all. Should it be covered, the list of applicable standards to BS7671 is woefully inadequate, particularly as all the reliability of electronics ones are required (and basically physically unverifiable), and the definition of an appliance needs considerable revision to cover anything which does not have a plug. BTW this would simply mean that all machinery would be fitted with a plug (we would need some bigger kinds to be designed) and this would actually reduce safety as the Earth conductor could become disconnected! A plug for a 10MW motor inverter could be quite interesting!
It would be useful Graham if you could produce a document showing a manufacturer who has these instructions? Manufacturers do not have to comply with BS7671, which covers fixed wiring installations only. An inverter will remove output on a short to Earth very quickly indeed, as an act of self-preservation, probably within a fraction of a milli-second. In what way does this not comply with BS7671? Verifying this kind of thing is very difficult for a typical Electrician, so you are saying that he may not install this equipment? This is the problem with regulations and standards of all kinds, "features" get added which have no place because "someone" thinks it is either necessary or would be nice, and everyone else nods in a SAGE way and lets it pass. It doesn't matter if the idea comes from Cenelec or elsewhere, if it doesn't make sense to practicality, it shouldn't be there. There are many other examples to be found, there is no shock risk at all from an Earthed motor with properly installed wiring, with whatever mechanical protection suits the environment. This is a case where no additional shock protection should even be mentioned. 419.2 is not necessary at all. It now seems to be thought that the Earth conductor is considered "dangerous" in itself and that all the Earthing and bonding is inadequate unless additional protection is added. This is ridiculous and has no reasonable danger scenario which is improved. Someone may like to make the case of why it is required, preferably generally, and not a motor in the middle of a lake used for swimming with convenient handrails attached. It is fundamentally impossible to fully comply with 419.2 if the inverter is not an appliance, which in my opinion it is, therefore not covered by BS7671 at all. Should it be covered, the list of applicable standards to BS7671 is woefully inadequate, particularly as all the reliability of electronics ones are required (and basically physically unverifiable), and the definition of an appliance needs considerable revision to cover anything which does not have a plug. BTW this would simply mean that all machinery would be fitted with a plug (we would need some bigger kinds to be designed) and this would actually reduce safety as the Earth conductor could become disconnected! A plug for a 10MW motor inverter could be quite interesting!
