MEN vs TNS
Posted: Wed Mar 02, 2022 9:17 pm
Had a discussion with an electrician that’s proposing to install a different type of earthing system at his main switchboard than the standard MEN/TNCS. It’s a larger type install, supplied from a transformer.
His intention is to install it as TNS. It’s not really something I’m familiar with, but understand a separate protective earthing conductor would be required to run back to the supply transformer. He advised me there was an article regarding this in ‘Electrolink Issue 136’, unfortunately I don’t have a copy, so not quite sure of all the details.
I’m just trying to understand whether or not this could be a compliant install in NZ? Does clause 5.1.4 of 3000 make allowance for this? Would it become a Part 1 solution, therefore requiring a certified design? I imagine if this were possible, the Network company would need to have some input, as you would need to connect the main earthing conductor from the installation to the neutral within the transformer?
My own belief is it should be installed as MEN and comply with Part 2, as Part 1 is reserved for non-typical installations that (for whatever reason) can’t comply with Part 2. You couldn’t just chose to install as TNS if MEN were an option? Thanks.
His intention is to install it as TNS. It’s not really something I’m familiar with, but understand a separate protective earthing conductor would be required to run back to the supply transformer. He advised me there was an article regarding this in ‘Electrolink Issue 136’, unfortunately I don’t have a copy, so not quite sure of all the details.
I’m just trying to understand whether or not this could be a compliant install in NZ? Does clause 5.1.4 of 3000 make allowance for this? Would it become a Part 1 solution, therefore requiring a certified design? I imagine if this were possible, the Network company would need to have some input, as you would need to connect the main earthing conductor from the installation to the neutral within the transformer?
My own belief is it should be installed as MEN and comply with Part 2, as Part 1 is reserved for non-typical installations that (for whatever reason) can’t comply with Part 2. You couldn’t just chose to install as TNS if MEN were an option? Thanks.