Okay, let's break down the electrical considerations for your dock project and address your questions. This is a significant distance and marine environment, so careful planning is essential.

Understanding the Challenges Distance

660ft is a long run. Voltage drop is your primary enemy. This means you need thicker wire or higher voltage to deliver adequate power without excessive loss.

Saltwater Environment

Corrosion is a huge issue. Marine-grade materials, proper grounding, sealing, and regular inspections are crucial.

Load Calculations

Your load calculation is essential to determine the minimum wire size. You've identified the major components, but remember to include all potential loads: lighting, outlets for tools, future expansion, etc.

Safety

Ground Fault Circuit Interrupters (GFCIs) are a must, and following the correct hierarchy of GFCIs is vital.

Let's tackle your specific questions



1. Aluminum vs. Copper Wire Copper



Pros

Higher conductivity than aluminum (smaller wire size for same amperage), more resistant to corrosion in marine environments, easier to work with (terminations, bending).

Cons

Significantly more expensive than aluminum, especially for larger wire sizes.

Aluminum



Pros

More cost-effective, especially for long runs and larger wire sizes.

Cons

Lower conductivity (requires larger wire size to carry the same amperage as copper), more susceptible to corrosion, requires special terminations and anti-oxidation compounds, more challenging to work with properly.

Recommendation

For a 660ft run in a marine environment, I would recommend using

copper conductors for the following reasons: Corrosion Resistance

Saltwater is extremely corrosive. Copper is naturally more resistant to corrosion than aluminum.

Long-Term Reliability

While aluminum can be used, the risk of corrosion and the need for specialized terminations introduce potential failure points over time. The cost savings of aluminum may not be worth the potential maintenance headaches and safety concerns.

2. Aluminum with Copper Ground vs. Copper Wire Mixed Metals

Using aluminum for the conductors and copper for the ground wire introduces potential galvanic corrosion. Where disimilar metals are joined in a marine environment, the more reactive metal (aluminum) will sacrifice itself for the more noble metal (copper) unless properly isolated.

Recommendation



Stick with all-copper conductors, including the ground wire. This will simplify the installation, reduce the risk of galvanic corrosion, and ensure a more reliable grounding system. Use proper corrosion-resistant lugs & connectors.3. 480V Transformers and Smaller Wire Theory

Stepping up to 480V (or a similar higher voltage) significantly reduces the current required to deliver the same amount of power. Lower current means smaller wire size and reduced voltage drop.

Considerations



Cost of Transformers

You'll need a step-up transformer at the shore and a step-down transformer at the dock. Transformers add significant cost.

Complexity

Transformer installations are more complex and require specialized knowledge.

Safety

Higher voltage introduces increased shock hazards. Careful design and installation are essential.

Efficiency

Transformers have losses. The total efficiency of the system needs to be considered.

Local Regulations

High voltage wiring may have additional permitting and inspection requirements.

Additional Equipment

You will have to convert back to 240v and 120v for the motors and battery charger.

Recommendation



480v Transformers are likely not cost effective. The cost of the transformers and associated equipment is unlikely to be offset by the savings in wire cost. The maintenance costs are also likely to be higher than a simple copper wire solution. I would only recommend transformers if the cost of copper wire is prohibitive.

Key Recommendations and Considerations



Load Calculation

Get a precise load calculation from a qualified electrician. Don't underestimate! Future-proof the installation for potential additions.

Voltage Drop Calculation

Based on the load and distance, a qualified electrician can calculate the minimum wire size required to keep voltage drop within acceptable limits (typically 3% or less). Voltage drop calculators are readily available online, but professional calculations are recommended.

Wire Type

Use marine-grade, tinned copper wire (e.g., UL 1426). The tinning provides extra corrosion resistance. THHN or XHHW insulation rated for wet locations is suitable.

Conduit

Use rigid PVC conduit, Schedule 80 for better protection. Glue all joints thoroughly and ensure the conduit is properly supported.

Expansion Joints

Absolutely crucial! Install expansion joints in the conduit runs to accommodate movement of the dock. Follow the manufacturer's recommendations for spacing.

Grounding

A solid, reliable grounding system is critical. Use a copper ground wire sized appropriately for the feeder. Bond all metal parts of the dock and equipment.

GFCI Protection



Shore Side

A GFCI breaker or GFCI outlet providing overall protection for the entire circuit. (GFPE)

Dock Subpanel

GFCI breakers for each individual circuit on the dock (outlets, lights, motors).

Subpanel Enclosure

Use a NEMA 4X enclosure for the subpanel at the dock. NEMA 4X enclosures are designed to be watertight and corrosion-resistant.

Terminations

Use marine-grade, tinned copper lugs and connectors. Apply an anti-oxidation compound (e.g., Noalox) to the connections to prevent corrosion.

Overcurrent Protection

Use appropriately sized breakers or fuses to protect the circuits.

Professional Installation

This is not a DIY project unless you are a qualified electrician with experience in marine environments. The risks of improper installation are too high.

General Advice



Consult with a Licensed Electrician

This is the most important step. A qualified electrician can perform the necessary calculations, select the appropriate materials, and ensure the installation meets all applicable codes and safety standards. They can also help you obtain the necessary permits and inspections.

Permits and Inspections

Contact your local permitting authority to determine the required permits and inspections for this type of project.

Documentation

Keep detailed records of the installation, including wiring diagrams, load calculations, and inspection reports. This will be helpful for future maintenance and troubleshooting.*

Regular Inspections: Periodically inspect the electrical system for signs of corrosion, damage, or loose connections. Address any issues promptly to prevent further problems.By carefully planning the system and employing qualified professionals, you can make sure that the dock wiring is safe, reliable, and long-lasting. Flag for review