In one of our recent project. There are multiple generators and individually feeding to each MDBs. Consultant instructed to loop all the Generator Neutral between each generators. Our proposal to provide individual neutral earthing for each generators.
Is it advisable to loop Generator Neutral Earthing (These generators are not synchronizing)
BS 7430: Code of Practice for Earthing
BS 7671: Requirements for Electrical Installations
NFPA 70: National Electrical Code.
NFPA 70 is not compatible with BS 7671 and BS 7430 (and indeed IEC 60364 series). Some of the fundamental requirements conflict. It's not often possible to comply with both simultaneously.
Usually, there is a "precedence of standards" clause in either the Contract, the General Specification, or the Particular Specification, which says:
"UAE national standards take precedence over ..." etc. ? What does that say for this project?
BS 7430: Code of Practice for Earthing
BS 7671: Requirements for Electrical Installations
That's good. BS 7430 has (or at least used to have) some nice diagrams for generator earthing for various permutations.
BS EN 50310 (Application of equipotential bonding and earthing in buildings with information technology equipment) might also be an interesting read for your situation.
- Andy.
Does this standard also tacle points like: Earthing downstream of a UPS, Connection of 'Clean' earth and Main earth, Connection to lightning protection downdrops?
Others here with access to the latest versions might be able to give you more detail, but generally you'd have to read several standards together to get a complete picture - e.g. BS 7430 for the general principles, BS 7671 for electrical safety (e.g. from electric shock), BS EN 62305 for LPS, BS 6701 for telecommunications, BS EN 50310 for IT equipment and so on (and they often cross-reference each other). For likes of UPSs it's often the case of making sure the basic principles are applies in each possible operating mode (mains failed running on battery, mains present supplying power through the UPS, and on direct mains (e.g. by-pass) - occasionally adopting differing approaches in different modes (e.g. some small UPS run as separated systems when disconnected from the mains rather than using ADS).
You might not find much about separate 'clean' earths though - most standards now go in the opposite direction and have a single common bonding network for everything, in order to keep the impedance (and therefore voltage difference) between any two points at a minimum.
- Andy.
Does this standard also tacle points like: Earthing downstream of a UPS, Connection of 'Clean' earth and Main earth, Connection to lightning protection downdrops?
'Clean earth' is not used in IEC standards, CENELEC Standards or British Standards.
But yes BS EN 50310 (IEC 30129) does cover functional earthing, combined protective and functional earthing, and combined protective and functional earthing, and BS EN 62305 covers the lightning and surge protection aspects. Both to be used in conjunction with BS 7671 (IEC 60364-4-44) and BS IEC 61000-5-2.
Earthing of circuits downstream of UPS should comply with BS 7671 (IEC 60364 series).
Just to contribute towards the ongoing debate, several years ago, I came across a similar project. Similar~ location. Anyway the 1MW generators were not linked as your consultant mentioned, due to nuisance ! tripping ( previously mentioned) the other factor these generators were some distance apart! with only Two that MAY! have had the potential to be powering devices within the same building. Each power source and location were clearly segregated as reasonably practical. We followed local regulations which gKenyon mentioned are not comparable with UK regulations. The initial issue / concern also, the units were NOT synchronized. Unable to provide more details due to contractual agreement.
We're about to take you to the IET registration website. Don't worry though, you'll be sent straight back to the community after completing the registration.
Continue to the IET registration site
