Electrical Design Coordination for Water Features By Chris Roy

Posted in Technical, News -

Electrical engineering is a very technical area of expertise best left to those that do it best – electrical engineers! This is especially important in water features, where life-safety depends on designing a system and specifying components and materials capable of keeping voltage out of the water, or ensuring that the system is immediately de-energized should a component fail.

While electrical design drawings for water features are done by electrical engineers, there are a few ways that this scope reaches out beyond the footprint of a fountain and can affect other areas of a project’s design and/or the scope of trades other than a project’s fountain builder.
Chris Roy, Director of Creative Design for OTL.

These “areas of overlap” are the focus of this article.

All of these overlaps are defined in Article 680 of the National Electric Code (NEC), Swimming Pools, Fountains, and Similar Installations (which, along with NEC Chapters 1 through 4, covers of electrical design for a project). While notes pertaining to these overlaps are usually indicated or alluded to on a water features electrical drawing(s), it’s important that items affecting other trades are clarified during the bidding process to avoid change orders and/or rework, and that designers understand certain limitations so they don’t waste time designing installations that aren’t allowable under the code.

Proximity

The most basic coordination issue is location; a water feature may not be located beneath an existing service drop/power line that isn’t at least 22.5’ above maximum water level, nor can a water feature be located beneath an existing communication cable that isn’t at least 10’ above maximum water level. Note that “maximum water level” is not the fountain’s designed static- or operating-water-level; it’s the level created by an edge, curb, or coping that would function as a weir allowing water to spill out if the overflow drain were clogged and the fountain was allowed to overflow. Also, note that the fountain can’t be located below existing power and communication cables at the stated minimum heights; electric and communication utilities are allowed to install new service above a fountain or pool with less clearance (not that any designer wants to see power lines hanging down over their new fountain!)

Next on the list after location is proximity, as in proximity to water features to other (non-fountain-related) electrical services. Generally speaking, underground wiring (except for wiring specifically related to the fountain) is not permitted to run beneath the fountain, nor within a perimeter around the fountain extending outward 5’ from the inside of the basin walls. There are exceptions to this, but due to the encasement, coverage, and corrosion-resistance requirements, they can be quite expensive and are best avoided.

Receptacles/outlets on the building or within adjacent landscape areas shall not be closer than 5’ to the inside wall of the fountain basin, and any outlets closer than 20’ to the fountain must be protected by a ground-fault circuit interrupter (GFCI).
For outdoor water features, any overhead lighting installed above the fountain, and outward to a perimeter extending 5’ beyond the edge of the water surface, must be installed at least 12’ above maximum water level. For indoor water features, this same 12’ clearance applies, though totally enclosed light fixtures and ceiling fans identified for use on porches or patios can be installed as low as 7.5’ above maximum water level provided the branch circuit supplying the equipment is protected by a GFCI. For a new fountain built at an existing location, the water feature can be built as close as 5’ to existing luminaires as long as the light fixtures are rigidly attached to the existing structure, and the branch circuit is protected by a GFCI.

UL Listed low voltage lighting, as typically used for landscape illumination, may be located within 5’ of the inside edge of the fountain basin wall provided the transformer is listed for swimming pool and spa use and meets the requirements set forth in 680.23(A)(2).

Bonding

Almost all metallic items larger in a water feature must be bonded, the exception being items with less than 4 square inches of surface area and penetrating the pool structure by less than 1”. Bonding connects the conductive elements of the fountain structure, metallic fountain components, nearby metallic objects (which may not be part of the water feature), and electrical equipment enclosures. This eliminates voltage gradients in the fountain area, by eliminating differences in voltage potential between individual conductive parts, reducing shock hazard. In non-electrician speak, the goal is to ensure that no human can become a conductor; tying all metal components together means that they all have the same potential (equipotential) or if one item were to be carrying voltage, they would all be carrying the same voltage, so if a person touches a metal item and any other conductor (such as the water), there is no electricity trying to flow between those two points, and thus no electrical shock.

This requirement includes, for example, a bronze sculpture that might be mounted atop a pedestal above water level within a fountain. This also includes architectural and/or landscape fixtures, fixed metal parts such as piping, fences, awning, etc. that are located within 5’ horizontally from the inside edge of the basin walls and 12’ vertically above maximum water level. Metallic items within 5’ of the fountain water but separated with a physical barrier so that a person cannot touch the object and water at the same time do not need to be bonded. All bonding connections must be made with an 8 AWG or larger solid copper wire, typically bare metal.

Grounding is closely related to bonding; in fact, the equipotential bonding described above is part of the fountain’s electrical grounding system; the bonded components are connected to the system’s grounded (neutral) connector. This bonding system extends beyond the metallic components we typically see in a fountain such as nozzles and lights – it must form what is called as an equipotential bonding grid, which encompasses the entire water feature.

For fountain constructed with “conductive shells” (typical concrete basin construction,) the equipotential bonding grid is created by bonding 8 AWG solid copper wire to the reinforcing steel in the fountain shell before concrete is poured. Bare rebar must be joined by steel tie wires, so that the entire rebar structure will be conductive. In fountains where epoxy-coated rebar is used, each segment of rebar must be ground down to bare metal so that the bond wire can be clamped to bare metal with an approved lug, then the connection must be repainted with epoxy spray to ensure integrity of the coating. The copper bonding wire must create a bonding grid as described in 680.26(1). Water features constructed with plastic liners are considered non-conductive, and do not require a bonding grid (though metallic items within the fountain must still be bonded.)

One of the easiest requirements of 680.26 to overlook is 680.26(2), which states that the equipotential bonding grid must extend to perimeter surfaces extending 3’ beyond the inside walls of the water feature, including unpaved areas. This means that the entire water feature must be ringed with a continuous loop of 8 AWG bare copper wire 18” to 24” from the inside wall of the pool, secured 4” to 6” below subgrade. This perimeter bonding wire must be tied to the fountains bonded reinforcing steel at at least four points, uniformly spaced around the perimeter of the fountain. There are many instances when the water feature is built well before adjacent hardscape is scheduled for installation – this is where coordination to meet bonding requirements is paramount.
When the fountain structure is bonded, at least four copper bonding wire pigtails need to be installed running away from the fountain structure, which can be connected to at a later date before the hardscape is installed. This is very simple and inexpensive with proper sequencing but becomes quite difficult and potentially expensive once the fountain concrete is placed and the rebar is encapsulated.

It is also paramount to remember that the water feature’s equipotential bonding grid must be tied back to the fountain’s grounding system. In a typical fountain built on grade, it’s a simple matter of running the bond wire back to the equipment vault in the trench along with the rest of the conduits going out to the fountain. In a water feature built over structure, however, this means installing a dedicated conduit for the bonding wire, an easy item to overlook. It’s always best practice, when possible, to install a few extra conduits anyway.

When most people think of the NEC and pools and fountains, they think of Article 680; however, Article 682 Natural and Artificially Made Bodies of Water also comes into play in our industry. Art. 682 is closely related to 680, and many of the guidelines are similar. It also has the same potential to be overlooked – certain areas near the water feature will need to be designed and built with equipotential bonding grids, lighting and outlets must be kept specific minimum distances from the water and GFCI protection used, metallic equipment must be bonded, etc.

Closing

Ultimately, the driving factor behind all of these rules is safety and accident prevention. Just like accidents can be prevented by planning ahead, cost overruns, change orders, and rework can be avoided as well by coordinate among designers and tradespeople to make sure that allowance for a complete electrical system are accounted for before construction, within a water feature and beyond.


Chris Roy is the Director of Creative Design for Outside the Lines, Inc. In this role, he leads the company’s design efforts, working with developers, architects, and landscape architects, as well as engineers and vendors. Contact him at ChrisR@otl-inc.com.

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