Bonding industrial buildings

I really don't see why this was coded C2. The water pipe can't possibly sustain several thousand amps without instant melting, and a 50mm cable that long will drop a good deal of the voltage anyway. The Gas pipe, although 5" is almost certainly connected to plastic distribution pipes within a moderate distance, and again there cannot be a significant external voltage difference without a very large current flow. I presume you have a local transformer, meaning your your supply is TNS, so the possibilities for significant Earth current to incoming pipework is very remote. I would be quite happy with these main bonding cables. Was a reason given for the C2, or a regulation reference?  Be aware that this kind of inspection of a large factory needs a very experienced inspector, otherwise this kind of report tends to be made!

I really don't see why this was coded C2. The water pipe can't possibly sustain several thousand amps without instant melting, and a 50mm cable that long will drop a good deal of the voltage anyway. The Gas pipe, although 5" is almost certainly connected to plastic distribution pipes within a moderate distance, and again there cannot be a significant external voltage difference without a very large current flow. I presume you have a local transformer, meaning your your supply is TNS, so the possibilities for significant Earth current to incoming pipework is very remote. I would be quite happy with these main bonding cables. Was a reason given for the C2, or a regulation reference?  Be aware that this kind of inspection of a large factory needs a very experienced inspector, otherwise this kind of report tends to be made!

100% David! I just wonder how much these erroneous codes, or at the very least, subjective codes, cost British industry. As you say, if the inspector was required to clearly set out their reasoning, it might just highlight deficiencies in understanding. Of course, that would also bring with it associated issues of spelling and grammar! 

Thank you for your reply . This is exactly what I thought and was a bit confused where the issue is. Yes we have our own transformer with a tncs supply . No no reference was given just main bond undersized? But a 50mm what size were the 2018 test persons expecting .