Okay, I understand. You've got a 400A overhead service drop for a restaurant, the roof height changed, and now you need to support 4 feet of 2" Rigid conduit (assuming 2" since that's the typical size for that conductor fill) with 500 kcmil copper conductors, ending about 5 feet above the new roof line. You want to avoid tension wire/guying. That's a common situation. Here's a breakdown of considerations and potential solutions

Understanding the Challenges
Weight

500 kcmil copper conductors are HEAVY. Rigid conduit is also heavy. The combination creates significant weight and leverage, especially extended 5 feet above the roof.

Wind Load

The conduit and service head will act like a sail, catching wind. This adds considerable stress to the mounting point.

Code Compliance (NEC)

NEC 230 covers service conductors and will have specific requirements about secure mounting, clearance from the roof, and protection from mechanical damage. Local codes may also have additional requirements.

Building Structure

You need to anchor the support to a solid structural member of the building. Aesthetics also matter, you can only put so many unistrut up a building before it becomes unappealing.

Potential Solutions (Alternatives to Tension Cables)

Here are solutions you should explore, starting with the most common and typically best approach:1. Rooftop Mast with Strut Support

This is the most likely solution:

Description

Use a robust galvanized steel mast designed for rooftop service entrances. These masts are specifically engineered to handle the weight and wind load.

Installation

Securely mount the mast base to the building's structure (not just the roofing material). Find a rafter, header, or other solid structural member. Use appropriate lag screws, through-bolts, or specialized roofing anchors. Run your conduit up through the mast. Use Unistrut or similar channel to brace the conduit to the mast at multiple points. Think of creating a strong, rigid triangle or rectangle.

Advantages

Very strong and stable. Aesthetically cleaner than tension wires. Designed specifically for this application.

Disadvantages

More expensive than tension wires. Requires careful installation to ensure proper support.2.

Braced Conduit Support (Similar to Mast but Simpler)



Description

A heavy-duty, rigid support system constructed from Unistrut, angle iron, or similar materials.

Installation

Create a strong base that is securely fastened to the building structure. Extend the support upwards, creating a framework that cradles the conduit. Use multiple clamps and fasteners to rigidly attach the conduit to the support structure. Consider a triangular bracing design for added strength.

Advantages

Can be customized to fit specific site conditions. Potentially less expensive than a pre-fabricated mast (depending on the materials used).

Disadvantages

Requires more fabrication work. May not be as aesthetically pleasing as a mast.3.

Combination of Short Mast and Wall Support



Description

Use a shorter mast (maybe 2 feet) mounted to the wall near the roofline. Then, use a heavy-duty wall bracket or strut to further support the conduit as it extends upward.

Installation

Mount the short mast securely to the wall. Run the conduit up through the mast. Use a wall bracket or strut system to support the conduit as it extends upward. Ensure the wall bracket is attached to a solid part of the wall structure.

Advantages

Can distribute the load between the roof and the wall. Potentially easier to install than a full-height mast.

Disadvantages

Requires careful planning to ensure proper support.

Important Considerations and Recommendations Consult with an Engineer

Seriously consider this. A structural engineer can calculate the wind load and weight stresses and design a support system that meets code and safety requirements. This is especially important for commercial buildings.

Permitting and Inspection

This type of work always requires a permit and inspection. The inspector will verify that the installation meets code requirements. Make sure you have approved drawings.

Material Selection

Use galvanized steel or other corrosion-resistant materials for all supports and hardware.

Secure Fastening

Use appropriate fasteners (lag screws, through-bolts, etc.) that are rated for the weight and wind load. Make sure the fasteners are compatible with the building materials.

Waterproofing

Properly seal any penetrations through the roof to prevent water damage.

Clearances

Maintain proper clearances from the roof and any other structures. (NEC 230)

Service Head

Use a weatherproof service head to protect the conductors from the elements.

Conductor Support

Make sure the 500 kcmil conductors are supported properly within the conduit and at the service head. This helps prevent strain on the connections. Use appropriate bushings and connectors.

Bonding/Grounding

Don't forget proper bonding and grounding of the conduit and enclosure.

Avoid Contact

Make sure the service drop is out of reach and cannot be contacted by anyone on the roof.

Step-by-Step Approach to Choosing a Solution1. Assess the Building Structure

Determine what solid structural members are available for mounting the support.2.

Calculate the Load

Estimate the weight of the conduit, conductors, and service head, and consider the potential wind load. This is where an engineer can be invaluable.3.

Evaluate the Options

Consider the pros and cons of each solution based on the building structure, load requirements, and budget.4.

Create a Detailed Plan

Develop a detailed plan that includes the materials needed, installation procedures, and safety precautions.5.

Obtain Permits and Inspections

Obtain all necessary permits and schedule inspections.6.

Install the Support System

Carefully install the support system according to the plan.7.

Run the Conduit and Conductors

Install the conduit and conductors, ensuring proper support and clearances.8.

Connect the Service Drop

Connect the service drop to the service head.9.

Test the Installation

Test the installation to ensure it is working properly and safely.

Safety First! Work with a qualified electrician who has experience with overhead service installations. Always de-energize the power before working on any electrical equipment. Use appropriate safety gear, including gloves, eye protection, and fall protection. Be aware of your surroundings and avoid any potential hazards.Given the weight and the 5-foot height requirement, I strongly* recommend using a properly sized rooftop mast supported by Unistrut. Consulting with a structural engineer to verify the design is essential for safety and code compliance. Flag for review