equipotential plane

[jwelectric]

Has anyone heard of a proposal or the rumors of the code making panel cloning 682.33 to 680 part IV.?

 

[bphgravity]

Re: equipotential plane

I'm sure it will be proposed however I have not heard or read anything to confirm or deny it.

 

[shortcircuit2]

Re: equipotential plane

Under the 2005 NEC, hot tubs and spas outdoors are required to have a equipotential bonding grid installed under paved walking surfaces as described in 680.26(C)

shortcircuit2

 

[jwelectric]

Re: equipotential plane

I have heard that there is a proposal being brought before panel 17 to require a grid under the grass or wodden deck.

I am looking for information about this

 

[peter d]

Re: equipotential plane

I'm curious what sticking a piece of copper wire in dirt will accomplish, and what benefits this will have.

 

[jwelectric]

Re: equipotential plane

The same thing that it would here,

682.33 Equipotential Planes and Bonding of Equipment Planes.
An equipotential plane shall be installed where required in this section to mitigate step and touch voltages at electrical equipment.
(A) Areas Requiring Equipotential Planes. Equipotential planes shall be installed adjacent to all outdoor service equipment or disconnecting means that control equipment in or on water, that have a metallic enclosure and controls accessible to personnel, and that are likely to become energized. The equipotential plane shall encompass the area around the equipment and shall extend from the area directly below the equipment out not less than 900 mm (36 in.) in all directions from which a person would be able to stand and come in contact with the equipment.

The requirement already exist

[ October 21, 2005, 04:29 AM: Message edited by: jwelectric ]

 

[shortcircuit2]

Re: equipotential plane

Installation of a copper equipotential bonding grid in the ground is designed to mask stray voltage that may be present in the earth. This will bring the equipment, earth, and person or animal to the same potential to prevent shock hazards that may be present from stray voltage.

Here is a link describing stray voltage...

http://www.pge.com/docs/pdfs/biz/power_quality/stray_volt.pdf

I not sure why we are only concerned about masking stray voltage in agricultural buildings "concrete floors" and swimming pools "paved" walking surfaces only and not placing these equipotential planes within the any conductive walking surface in these areas

shortcircuit2

 

[peter d]

Re: equipotential plane

I guess the confusing part for me is the effectiveness of such a system. Dirt is a poor conductor, or put another way, an unpredictable conductor.

We know that we only need to connect a #6 to a driven ground rod, and that is larger than it needs to be.

I need to do some more research on this.

 

[charlie b]

Re: equipotential plane

Originally posted by peter d: Dirt is a poor conductor, or put another way, an unpredictable conductor.

A box of dirt is a poor conductor. But a planet's worth of dirt is an extraordinarily good conductor.

Consider the bottom points of two ground rods spaced 8 feet apart. Draw a straight line between the two points. Draw a second line that starts at one point, curves down 6 inches, heads toward the second rod, and curves back up to the second point. Draw a third line that curves down 18 inches and curves left 10 inches, before heading to the second point. Keep drawing lines. Draw the 100,123,456th line from one point to the other, via China.

You have a nearly infinite number of parallel paths for current to take, when traveling from one point to the other. Each path may have no better ability to conduct current than, say, a box of dirt. But a whole bunch of such parallel paths brings the total net resistance down to a small value.

 

[peter d]

Re: equipotential plane

Thanks Charlie. Once again, your excellent description saves the day.