A clean tie-in at the State Pier is a quiet boat at the dock.

§ 01 · What we install

A shore-power tie-in is four parts: the inlet on the boat, the cordage between the boat and the dock, the galvanic isolator (or transformer), and the dockside pedestal that the cord plugs into. We work all four. The pedestal is the marina's, but if it has been pulled out of the ground or damaged we coordinate with the harbormaster — on the State Pier and Pier 3, that's the New Bedford Harbor Development Commission.

The inlet is the only part on the boat that lives full-time in the splash zone. The two products we trust on commercial vessels are SmartPlug (locks positively, weather-sealed, won't burn the way a Marinco connection can) and Hubbell HBL (industrial standby, the choice for 100 A steel-hull installations). Marinco was the standard before 2010 and is still common; we will work with it but we will tell the captain when it should be replaced.

§ 02 · The piers we work

We are alongside on every pier in the harbor every week. We know which pedestals work, which trip on a 30-mA fault before the boat is plugged in (a sign the dock-side wiring is the problem, not yours), and which ones short to ground when the wind is in the wrong direction.

• State Pier — managed by MassDevelopment. Mostly 50 A and 100 A pedestals, replaced 2019.
• Pier 3 — HDC. Mostly 50 A. Two pedestals at the south end have been intermittent since 2024 — we keep an eye on them.
• Leonard Wharf — HDC. 30 A and 50 A. Older infrastructure but in good repair.
• South Terminal — South Terminal Operations. 100 A and 100 A 3-phase, the only 3-phase landside tie-in available to the fishing fleet in the harbor.
• Pope's Island Marina — HDC marina. 30 A and 50 A. Mostly recreational but we work commercial vessels here too.

§ 03 · Galvanic isolation

If your boat lives on shore power for any sustained period and you are losing zinc anodes faster than the season explains, the cause is almost always low-voltage DC galvanic current entering the boat through the shore safety ground. The fix is a galvanic isolator (ABYC A-28-rated) installed in the safety-ground line between the inlet and the boat's ground bus.

The isolators we install are Victron Energy VDI-32 (32 A pass-through) and the Blue Sea Systems 7600 series. For boats with persistent stray-current problems, we install an isolation transformer instead — more expensive, but a complete galvanic break.

Diagnosis is with a silver/silver-chloride reference cell, not guesswork. We dunk the cell off the bow and read the boat-to-water potential while plugged and unplugged.

§ 04 · Leakage current and the new GFP rules

The 2023 NEC raised the visibility on leakage-current trips. NEC 555.35 caps marina-side ground-fault protection at 30 mA, and ABYC E-11 caps vessel-side equipment-protection devices (EPDs) at 5 mA at the cord set, with type-A or type-F protection.^[1] If your boat has been tripping the dock pedestal on plug-in, the most common single cause is a moisture path inside the cordage, and the second most common is a chronic leakage in the boat's water heater.

We measure leakage with a Megger MIT400 and a Fluke 1587. We document the reading at every tie-in. For boats over the 5 mA limit, we hunt the source — usually three afternoons of patient circuit isolation, almost never a single dramatic find.

§ 05 · Cost & lead time

Routine 50-A inlet replacement (SmartPlug, including labor): $720–$1,180. Same with new cordage: $1,180–$1,940. Galvanic isolator install (Victron VDI-32): $640–$880. Isolation transformer install (Charles 100 A): $4,200–$6,800 plus the transformer. Most of these are one-day jobs we can slot inside a week. The rates breakdown is on the rates page.

Cross-references: P-04 (switchboards) when the inlet is being replaced as part of a board upgrade, P-07 (survey prep) when the surveyor has flagged the cord set, and the December 2025 bulletin for the long-form on cordage failure modes.