You're on the right track, but let's break down the problem and clarify a few points.

NEC Requirements and Bending Radius



NEC 312.6(B)(1)

This is the key section. It specifies minimum bending space at terminals for conductors without conductors entering directly opposite. This is usually the situation you're describing. This section links to Table 312.6(B) for the required bending space based on the conductor size and voltage.

Table 312.6(B)

Look up the bending space required based on your 500 kcmil conductor and 480V. This table specifies a minimum bending space from the termination point to the opposite wall of the enclosure.

No specific bending radius for under 1000V in general NEC

You are correct. The general code doesn't dictate a specific "times the diameter" bending radius for conductors under 1000V the same way it does for higher voltages (NEC 300.34). However, you must follow the manufacturer's installation instructions for the conductor. Some manufacturers do specify a minimum bending radius for their cables. This is often (but not always) in line with the 6x diameter rule of thumb.

Calculating the Required Distance (Revised Approach)


Determine the Required Bending Space per NEC Table 312.6(B)

This table gives you the minimum distance from the terminal to the opposite wall of the enclosure to allow for a proper bend. For 500 kcmil, you are likely going to need more than 12 inches.2.

Consider the Vertical Distance between Enclosures

The distance between the bottom of your disconnect enclosure and the bottom of your meter enclosure influences the tightness of the bend. If the enclosures are close together vertically, you will need even more horizontal space to achieve the proper bend without exceeding the conductor's minimum bending radius.3.

Account for Cable Entry

You're bringing the cables in from the bottom of both enclosures. This is important because it means the bend needs to accommodate this entry point.4.

Spacing of Conductors

You do not need to multiply the bending space by 3. The bending space required by NEC 312.6(B) is the space needed for each conductor. The main concern is the horizontal spacing between the cable entry points in each enclosure. You need enough horizontal spacing so that, as each conductor curves upward from the bottom of the disconnect, they don't interfere with each other. Consider the conductors will be roughly parallel and spaced slightly apart. This spacing should be no more than the diameter of the conductor. Minimum spacing is likely the diameter of the conductor itself for ease of installation and heat dissipation.5.

Practical Considerations



Ease of Installation

The NEC provides minimums. In reality, providing extra space makes the installation much easier, reduces stress on the conductors and terminations, and simplifies future maintenance.

Heat Dissipation

Closely packed conductors can generate heat. Consider spacing them slightly further apart than the minimum to promote better airflow.

Physical Obstructions

Account for any physical obstructions (walls, pipes, etc.) that might impact the cable routing.

Example Scenario

Let's say Table 312.6(B) requires a bending space of 12 inches from the terminal to the opposite wall for 500 kcmil at 480V. Let's also assume the vertical distance between the bottom of the disconnect and the bottom of the meter is only 6 inches. You will need to ensure the horizontal distance between the disconnect and meter is

greater than 12 inches (probably closer to 16-18 inches) to accommodate the upward bend. If you simply put the equipment side-by-side, it could be difficult to achieve this bend without exceeding the conductor's bending radius. The cable entry holes in the bottom of both enclosures should be spaced horizontally apart by at least the diameter of the conductor (.93"). A larger enclosure might be a less expensive solution than the extra horizontal distance needed to achieve the required bending radius.

Important Steps


Consult NEC 312.6(B) and Table 312.6(B) to determine the REQUIRED bending space.2. Review the Cable Manufacturer's Specifications

Check for any specific minimum bending radius recommendations from the cable manufacturer.3.

Consider the Vertical Distance

Account for the vertical distance between the enclosures.4.

Prioritize Ease of Installation and Maintenance

Give yourself ample room for the bend.5.

Document your rationale

Ensure your design is documented, justifying the selected spacing and compliance with applicable codes and standards.

Disclaimer: I am an AI chatbot and cannot provide professional engineering advice. Consult with a qualified electrical engineer for specific designs and code compliance. A licensed electrician should perform the installation. This information is for educational purposes only. Flag for review