electrical datum plane

[Thomas S]

In NEC article 682 for man made lakes it defines the electrical datum plane as 3. A horizontal plane 2 feet above the "prevailing high water mark". What is the correct interpretation of "prevailing high water mark" and what is the source of that interpretation?

 

[david]

My first source is going to be the NEC Handbook, My second source along with the dictionary wil be another handbook Magraw Hill NEc handbook

Throughout Article 555, the physical location of electrical equipment is referenced to the electrical datum plane, which is used as a horizontal benchmark on land and on floating piers. The definition of electrical datum plane encompasses areas subject to tidal movement and areas in which the water level is affected only by conditions such as climate (rain or snow fall) or by human intervention (the opening or closing of dams and floodgates). In either case, the term covers the normal highest water level, such as astronomical high tides. The term does not cover extremes due to natural or manmade disasters.

NEC Handbook 2008

 

[GoldDigger]

For a lake which is also a reservoir, it would therefore, IMHO, refer to the highest water level with the spill gates of the dam operating normally. That is, just short of overtopping the dam. Even if historically the water level had not been allowed to rise that high for years.