Let's break down the NEC implications of your proposed wiring diagram for outdoor pole-mounted flood lighting. Here's a critical analysis, incorporating common NEC considerations

Concerns and Corrections Needed:

1. Overcurrent Protection at Point of Ampacity Change

This is the biggest issue and violates NEC 240.4(D)(5) and potentially other subsections.

You MUST have overcurrent protection (a fuse or circuit breaker) at the point where the wire size changes from #10 AWG to #12 AWG. The #12 AWG wire is rated for a lower ampacity than the #10 AWG and can overheat and cause a fire if subjected to currents above its rating. Your current setup has a 30A breaker potentially feeding a #12 wire. That's a significant hazard. The fuse you mentioned is good but how is it wired? It needs to be at the start of #12 AWG conductor.2. 30A Breaker and #12 AWG Wire

You cannot protect a #12 AWG wire with a 30A breaker. #12 AWG copper is typically rated for a maximum of 20A (check the insulation type, THHN/THWN is 20A). You'll need to reduce the breaker size or upsize the wire.3.

Fuse Sizing

The fuse protecting the #12 AWG wire should be sized appropriately for the luminaire's load (and the wire). It should be no larger than the ampacity of the #12 AWG wire (usually 20A for typical insulation types) and also take into account the inrush current of the floodlight. If the luminaire requires less than 20A, the fuse should match that requirement.4.

Continuous Load

Outdoor lighting is often considered a continuous load (operating for 3 hours or more). NEC 210.20(A) requires that the overcurrent protection (breaker) be rated at no less than 125% of the continuous load. So, if your luminaire draws, say, 10A continuously, you need a breaker (or fuse) rated for at least 1.25 10A = 12.5A. In practice, you'd use a 15A breaker (the next standard size up). The wiring still needs to be able to handle that 15A.
5.

Grounding

Your diagram doesn't explicitly show grounding. Make sure you have a properly sized grounding conductor (likely #10 AWG copper, based on the 30A breaker) running to each pole and connected to the metal enclosure of the luminaire. The ground wire should originate from the panel's grounding bus. This is essential for safety.6.

Wet Location Considerations

All wiring and connections must be rated for wet locations (NEC Article 410 and 680 for specific requirements). Use waterproof boxes, conduit, and connectors. Direct burial cable must be rated for direct burial.7.

Cable Type and Burial Depth

What type of cable are you using? For underground runs, you'll likely need UF (Underground Feeder) cable or cable in conduit. NEC Table 300.5 specifies burial depths based on cable type, voltage, and location. Typically, UF cable requires at least 24 inches of burial depth, and conduit may reduce that depth. Check local codes for specific requirements.
8.

Disconnect Means

Consider a local disconnect means (switch or fused disconnect) at each pole for servicing the luminaires. This is not always required, but it greatly enhances safety.9.

Working Space: 110.26 requires sufficient access and working space around electrical equipment. Make sure the breaker panel is accessible.

Revised Recommendations and NEC Implications

Here's how to correct the issues and a summary of NEC relevant to your project.1. Determine the Luminaire's Load

Find the wattage of each floodlight. Divide the wattage by the voltage (120V or 240V, depending on your setup) to determine the current draw (amps) of each light.2.

Calculate Total Load

If you're running multiple lights on a single circuit, add up the individual current draws to get the total load. Account for continuous load multiplier.3.

Select Wire Size and Overcurrent Protection

Based on the total load of the circuit, choose a wire size that can handle the current. #12 AWG copper (THHN/THWN) is generally good for 20A, #10 AWG for 30A, #14 for 15A. Remember to derate for temperature and conduit fill if necessary. The breaker size should be no larger than the ampacity of the smallest wire on the circuit. If you MUST reduce wire size for the individual luminaires, place a fuse immediately at the point where the wire size changes. Size the fuse for the smaller wire's ampacity and the luminaire's load.4.

Grounding

Run a properly sized grounding conductor (#10 AWG if using a 30A breaker) along with the circuit conductors. Connect it to the grounding bus in the panel and to the metal enclosure of each luminaire.5.

Wet Location Compliance

Use appropriate enclosures, connectors, and wiring methods suitable for wet locations.

Example Corrected Wiring (Illustrative)

Let's say each floodlight draws 8A. You have two lights, totaling 16A. Accounting for 125% continuous load 16A 1.25 = 20A

Breaker

Use a 20A breaker in the panel.

Main Cable

Run #12 AWG UF cable from the panel to the first pole.

First Pole

In a waterproof junction box at the base of the pole: Split the #12 AWG cable. One run goes to the first floodlight. Terminate the first run to a fuse holder with a 10A fuse (sized for the 8A floodlight). Connect the other side of the fuse holder to #14 AWG THHN/THWN wire inside conduit up to the floodlight. The other run of #12 AWG continues to the next pole.

Second Pole

Repeat the process from the first pole, including the fuse.

Grounding

Run a #12 AWG grounding conductor from the panel's ground bus to each pole and connect it to the luminaire's grounding terminal.

Important NEC Articles to Review



Article 110

Requirements for Electrical Installations (General).

Article 210

Branch Circuits.

Article 225

Outside Branch Circuits and Feeders.

Article 240

Overcurrent Protection.

Article 250

Grounding and Bonding.

Article 300

Wiring Methods.

Article 310

Conductors for General Wiring

Article 410

Luminaires, Lampholders, and Lamps (Especially Part V for Outdoor Installations).

Article 680

Swimming Pools, Fountains, and Similar Installations (Relevant if your lighting is near a water feature).

Disclaimer: This information is for educational purposes only and does not constitute professional electrical advice. Consult with a qualified and licensed electrician to ensure your wiring complies with all applicable codes and regulations and is safe for your specific application.* The NEC is a complex document, and local codes may have additional requirements. Your local electrical inspector has the final say on code compliance.In summary, your current wiring diagram has major safety issues. Prioritize overcurrent protection at wire size changes and ensure all components are properly rated for the load and environment. Get professional help! Flag for review