Private docks
What section of the National Electrical Code would one use to make the electrical installations for a private dock or pier?
Article 555 covers the installation of wiring and equipment in the areas comprising fixed or floating piers, wharves, docks, and other areas in marinas, boatyards, boat basins, boathouses, yacht clubs, boat condominiums, docking facilities associated with residential condominiums, any multiple docking facility, or similar occupancies, and facilities that are used, or intended for use, for the purpose of repair, berthing, launching, storage, or fueling of small craft and the moorage of floating buildings.
What Article 555 does not cover are private, noncommercial docking facilities constructed or occupied for the use of the owner or residents of the associated single-family dwelling
Then what section of the NEC would one use?
ARTICLE 682 Natural and Artificially Made Bodies of Water
In this article we are told that the electrical installations must follow;
682.3 Other Articles. Wiring and equipment in or adjacent to natural or artificially made bodies of water shall comply with the applicable provisions of other articles of this Code, except as modified by this article. If the water is subject to boat traffic, the wiring shall comply with 555.13(B).
If this dock is subject to boats then there are some pretty stringent rules that must be followed. For the branch circuit wiring to lights and receptacles on this dock we are sent back to 555.13(B)
(B) Installation.
(2) Outside Branch Circuits and Feeders. Outside branch circuits and feeders shall comply with Article 225 except that clearances for overhead wiring in portions of the yard other than those described in 555.13(B)(1) shall not be less than 5.49 m (18 ft) above grade.
(5) Where cables pass through structural members, they shall be protected against chafing by a permanently installed oversized sleeve of nonmetallic material.
(5) Protection. Rigid metal or nonmetallic conduit suitable for the location shall be installed to protect wiring above decks of piers and landing stages and below the enclosure that it serves. The conduit shall be connected to the enclosure by full standard threads. The use of special fittings of nonmetallic material to provide a threaded connection into enclosures on rigid nonmetallic conduit, employing joint design as recommended by the conduit manufacturer, for attachment of the fitting to the conduit shall be acceptable, provided the equipment and method of attachment are approved and the assembly meets the requirements of installation in damp or wet locations as applicable.
Article 225 addresses outside feeder and branch circuits with Part II addressing a separate building or structure.
225.31 Disconnecting Means. Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure.
225.36 Suitable for Service Equipment. The disconnecting means specified in 225.31 shall be suitable for use as service equipment.
Exception: For garages and outbuildings on residential property, a snap switch or a set of 3-way or 4-way snap switches shall be permitted as the disconnecting means.
What about a grounding electrode system? This requirement will be found in Part II of 250
250.32 Buildings or Structures Supplied by a Feeder(s)
or Branch Circuit(s).
(A) Grounding Electrode. Building(s) or structure(s) supplied by feeder(s) or branch circuit(s) shall have a grounding electrode or grounding electrode system installed in accordance with Part III of Article 250. The grounding electrode conductor(s) shall be connected in accordance with 250.32(B) or (C). Where there is no existing grounding electrode, the grounding electrode(s) required in 250.50 shall be installed.
Exception: A grounding electrode shall not be required where only a single branch circuit, including a multiwire branch circuit, supplies the building or structure and the branch circuit includes an equipment grounding conductor for grounding the normally non–current-carrying metal parts of equipment.
It is through this exception that I made the comment that for a single branch circuit I would not install a rod at a pier.
(B) Grounded Systems. For a grounded system at the separate building or structure, an equipment grounding conductor as described in 250.118 shall be run with the supply conductors and be connected to the building or structure disconnecting means and to the grounding electrode(s). The equipment grounding conductor shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded. The equipment grounding conductor shall be sized in accordance with 250.122. Any installed grounded conductor shall not be connected to the equipment grounding conductor or to the grounding electrode(s).
The requirement not to connect the equipment grounding conductor to the grounded (neutral) conductor that the term “isolated from†comes into play. It does not mean to cut the equipment ground conductor and reconnect it to the ground rods.
The requirements for the equipment grounding conductor supplied with the branch circuit for a body or water found in Article 682 that modifies the requirement for equipment grounding found in Part II of 250
682.31 Equipment Grounding Conductors.
(A) Type. Equipment grounding conductors shall be insulated copper conductors sized in accordance with 250.122 but not smaller than 12 AWG.
The equipment grounding conductor installed with the branch circuit must be insulated and no smaller than #12. UF cable does not have an insulated equipment grounding conductor so the use of UF is disallowed.
682.32 Bonding of Non–Current-Carrying Metal Parts.
All metal parts in contact with the water, all metal piping, tanks, and all non–current-carrying metal parts that may become energized shall be bonded to the grounding bus in the panelboard.
The metal dock must be bonded to the equipment grounding conductor in the panel at the pier or dock and as outlined below this bonding must be done with a solid copper #8 conductor
The disconnect installed at the pier or dock must also have an equipotential plane shall be installed.
682.33 Equipotential Planes and Bonding of Equipotential 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.
(C) Bonding. Equipotential planes shall be bonded to the electrical grounding system. The bonding conductor shall be solid copper, insulated, covered or bare, and not smaller than 8 AWG. Connections shall be made by exothermic welding or by listed pressure connectors or clamps that are labeled as being suitable for the purpose and are of stainless steel, brass, copper, or copper alloy.
Here is the proper way to install electrical circuits to a dock as outlined in this thread. To do anything less will result in an unsafe and dangerous installation.
Everything posted here is straight from the 2008 code cycle. It is not myth or fantasy nor would anything I think make it safer but the requirements straight from the rules governing the safety of persons and equipment.