Marina grounding

[Andy35]

Why NEC 2017 does not ask for marina installations isolating transformer (Straying currents, HV-MV faults) and GFCI devices for all circuits in LV distribution panels?

Thanks,

Andrew

 

[Dennis Alwon]

I found this

555.4 Distribution System. Yard and pier distribution systems
shall not exceed 1000 volts phase to phase.

And this

555.5 Transformers. Transformers and enclosures shall be
specifically approved for the intended location. The bottom of
enclosures for transformers shall not be located below the electrical
datum plane.

 

[Andy35]

That is a big issue, connection between MV neutral and LV neutral allows that the ground fault current in a distribution station 34.5/12.47kV (in vicinity of Marina) on 34.5kV side fault located before the fuse) will flow mostly through boat and water (lower resistivity than soil) and it could produce voltages which could be dangerous to the people and currents which could melt ground wire (7.2kV makes similar issue) . That is a reason why I, for time being, suggest an improved Wisconsin dairy connection and in the future an improved Southern Californian solution. On the low voltage side we need GFCI for all circuits.

Thanks,

Andrew

 

[Andy35]

That could a big issue, I.e. connection between MV neutral and LV neutral allows that the ground fault current in a distribution station 34.5/12.47kV (in vicinity of Marina) on 34.5kV side fault (located before the fuse) will flow mostly through the boat and the water (lower resistivity than soil) and it could produce voltages which could be dangerous to the people and currents which could melt ground wire (7.2kV ground fault causes a similar issue, but probably lower LNPR)) . That is a reason why I, for time being, suggest an improved Wisconsin dairy connection and in the future an improved Southern Californian solution. On the low voltage side we need GFCI for all circuits.

As I know in many EU countries GFCIs have been used in all circuits even sometimes for the panel main CB.

Also MV ground is isolated from LV neutral and I have never heard that they had ESD.

Thanks,

Andrew

 

[topgone]

That could a big issue, I.e. connection between MV neutral and LV neutral allows that the ground fault current in a distribution station 34.5/12.47kV (in vicinity of Marina) on 34.5kV side fault (located before the fuse) will flow mostly through the boat and the water (lower resistivity than soil) and it could produce voltages which could be dangerous to the people and currents which could melt ground wire (7.2kV ground fault causes a similar issue, but probably lower LNPR)) . That is a reason why I, for time being, suggest an improved Wisconsin dairy connection and in the future an improved Southern Californian solution. On the low voltage side we need GFCI for all circuits.

As I know in many EU countries GFCIs have been used in all circuits even sometimes for the panel main CB.

Also MV ground is isolated from LV neutral and I have never heard that they had ESD.

Thanks,

Andrew

Please read the poster above your recent posts.