Floating Buildings

Article 553 handles a structure that is a building in every functional way but has no soil to bond to. The grounding scheme relies on an insulated equipment grounding conductor run back to shore rather than a local electrode, and the feeder connection has to tolerate the constant motion of the float without fatiguing or losing continuity.

The service and feeder thinking is what carries this article. You are extending shore power across a flexing gangway to a moving load, so I plan the feeder route, the strain relief, and above all the grounding continuity so a fault always has a low-impedance path home, not a path through the water.

When it applies

Article 553 deals with buildings that actually float on water and get their power from shore. You are wiring a structure that moves, rides swells, and sits surrounded by a conductive medium, so the service, the feeder, and especially the grounding and bonding have to account for all of that. The connections have to tolerate motion without loosening or chafing.

Common mistakes

• Running rigid feeder connections that a moving structure will slowly work apart.
• Getting the grounding and bonding wrong, which around water is a direct path to a shock hazard.
• Ignoring the corrosive marine environment when picking materials.

In the field

On a floating structure the grounding is where I spend my attention, because you have got a moving building over water and no margin for a loose bond. Get the bonding right and flexible, and the rest of the install falls into line.