Mysterious temporary earth fault in 3 phase motor starter enclosure

[sysrq]

During the time of phase absence measurement temporary earth fault was detected on the enclosure of 3 phase motor starter.
I assume earth fault loop impedance testing was performed in recent history but somehow it failed to protect from consequences.
Due to dodgy British standards and regulations these things happen. In every factory is a mess in terms of wire colour codes. Only in 2004 we decided to use IEC colour code.
Many SWA cables have no proper conductor with green-yellow insulation, we can't rely just on steel armour, some electricians are using yellow or black wire as an protective earth conductor which results in great confusion for others.
For a very long time we refused to implement RCD protectors, while the rest of the Europe was using them already for quite a long time.
Another thing is MEM isolator boxes and fuse boards without normal earth busbar.
So the question is, what could have caused mysterious temporary earth fault on a motor starter enclosure with step down transformer? Box assembled in 70's.

 

[Darkwood]

During the time of phase absence measurement temporary earth fault was detected on the enclosure of 3 phase motor starter.
I assume earth fault loop impedance testing was performed in recent history but somehow it failed to protect from consequences.
Due to dodgy British standards and regulations these things happen. In every factory is a mess in terms of wire colour codes. Only in 2004 we decided to use IEC colour code.

Can you expand on what you mean here - why just because our original regulations did not match that of the EU do you say our regulations are dodgy - many countries around the world have their own regulations and standards that do not match with the EU or BS standards but it doesn't mean they are dodgy.

Many SWA cables have no proper conductor with green-yellow insulation, we can't rely just on steel armour, some electricians are using yellow or black wire as an protective earth conductor which results in great confusion for others.

If the CSA of the steel wire is sufficient to be used as a protective conductor then their is no reason why it cannot be used as this is standard practice, using a spare core as a earth is also standard practice as long as it is marked up correctly, I do not understand where the confusion is in these common practices.

For a very long time we refused to implement RCD protectors, while the rest of the Europe was using them already for quite a long time.

We have used them for decades - but regulations on requirements for their use from the 16th edition onwards has seen their implementation increase to the point we have them now throughout domestic etc.. The standards of other EU countries is by no means a good comparative, I have seen some shocking installs in public buildings in many countries, the BS standards is by far tighter and more keen than most EU members thus safer.

Another thing is MEM isolator boxes and fuse boards without normal earth busbar.

Can you expand on this... What is a normal earth bar?.. MEM products are commonly used in Britain and I have never had any issue with their earthing arrangments.

So the question is, what could have caused mysterious temporary earth fault on a motor starter enclosure with step down transformer? Box assembled in 70's.

In answer to your question - we need a lot more information, the testing and results you have done, the nature of the fault you have found, what are the consequences of this fault ie - is it tripping the overload device etc.

A little more info please then we may be able to help you out.

 

[Pete999]

During the time of phase absence measurement temporary earth fault was detected on the enclosure of 3 phase motor starter.
I assume earth fault loop impedance testing was performed in recent history but somehow it failed to protect from consequences.
Due to dodgy British standards and regulations these things happen. In every factory is a mess in terms of wire colour codes. Only in 2004 we decided to use IEC colour code.

Can you expand on what you mean here - why just because our original regulations did not match that of the EU do you say our regulations are dodgy - many countries around the world have their own regulations and standards that do not match with the EU or BS standards but it doesn't mean they are dodgy.

Many SWA cables have no proper conductor with green-yellow insulation, we can't rely just on steel armour, some electricians are using yellow or black wire as an protective earth conductor which results in great confusion for others.

If the CSA of the steel wire is sufficient to be used as a protective conductor then their is no reason why it cannot be used as this is standard practice, using a spare core as a earth is also standard practice as long as it is marked up correctly, I do not understand where the confusion is in these common practices.

For a very long time we refused to implement RCD protectors, while the rest of the Europe was using them already for quite a long time.

We have used them for decades - but regulations on requirements for their use from the 16th edition onwards has seen their implementation increase to the point we have them now throughout domestic etc.. The standards of other EU countries is by no means a good comparative, I have seen some shocking installs in public buildings in many countries, the BS standards is by far tighter and more keen than most EU members thus safer.

Another thing is MEM isolator boxes and fuse boards without normal earth busbar.

Can you expand on this... What is a normal earth bar?.. MEM products are commonly used in Britain and I have never had any issue with their earthing arrangments.

So the question is, what could have caused mysterious temporary earth fault on a motor starter enclosure with step down transformer? Box assembled in 70's.

In answer to your question - we need a lot more information, the testing and results you have done, the nature of the fault you have found, what are the consequences of this fault ie - is it tripping the overload device etc.

A little more info please then we may be able to help you out.

What he said ^^^^^^^^^^^^^^^^^^^^^^^

 

[telectrix]

what he said ^^^^. and what he said ^^^.
and if OP is in greece, why bother. eu is a big place.