Okay, let's break down what you need to specify and some considerations for supporting that 1-1/2" RMC conduit on a red brick building, going up four stories. This is a common situation, and we can get you on the right track.

Understanding the Requirements

The reviewer wants to ensure the conduit is securely and safely supported, able to withstand the weight of the conduit itself, the weight of the conductors inside, wind loads, ice loads (if applicable in your area), and general vibration. They want to see that you've considered the structural integrity of the brick wall and are using appropriate anchoring methods.1. Conduit Support Spacing and Bracket Type NEC (National Electrical Code) Spacing

The NEC specifies maximum support spacing for RMC conduit. For 1-1/2" RMC, the maximum support spacing is

10 feet (3.0 meters). (NEC Article 344.30(B)) This means you'll need a bracket approximately every 10 feet. However, less than 10 feet is almost always better and results in less stress on the conduit and anchors. I often reduce this to 8 feet for exterior runs and 6 feet in areas with heavy vibration. Consider the load you're putting on the conduit - is it just THHN wire, or are you running heavy feeder cables? Bracket Types

Several types of brackets can be used. Here are a few common options and their pros/cons:

One-Hole Straps

These are the simplest, but not ideal for a four-story run on the exterior. They don't provide great lateral support. Avoid these for this application.

Two-Hole Straps/Clamps

Better than one-hole, offering more stability. These are acceptable, but you need to ensure they are heavy-duty enough.

Conduit Clamps with Stand-off Brackets

This is a better option. The clamp securely holds the conduit, and the stand-off bracket provides a space between the conduit and the wall, allowing for airflow and preventing moisture buildup. This is what I'd recommend. Choose those made of galvanized steel or stainless steel.

Riser Clamps

Specifically designed for vertical conduit runs. These have a saddle-like design that distributes the weight of the conduit more evenly. A good option for supporting the weight of the long run. Consider combining these with the stand-off brackets at intervals.

Material



Galvanized Steel is the standard for exterior applications. Stainless Steel provides superior corrosion resistance, especially in coastal or harsh environments, but it's more expensive. Avoid aluminum in direct contact with dissimilar metals (like steel hardware), as it can cause galvanic corrosion.2. Anchor Type, Size, Material, and Embedment

This is where you need to consider the brick wall's construction and condition. Red brick can be soft and crumbly in some older buildings. If there's significant deterioration of the brick, I highly recommend consulting a structural engineer. Anchor Types



Sleeve Anchors

These are a good all-around choice for brick. They consist of a bolt surrounded by a sleeve. When tightened, the sleeve expands, gripping the brick. Easy to install, readily available, and provide good holding power.

Wedge Anchors

Similar to sleeve anchors but generally provide higher load capacities. The wedge creates a stronger mechanical interlock with the brick. Can be more difficult to install precisely.

Epoxy Anchors (Adhesive Anchors)

This is likely what the reviewer is thinking of when they mention "epoxy embedment." You drill a hole, inject epoxy into the hole, and then insert a threaded rod. The epoxy bonds the rod to the brick. Provides very high pull-out strength, especially in weaker brick. Requires careful installation to ensure proper bonding. The "embedment depth" is the depth to which the threaded rod is inserted into the epoxy-filled hole. Epoxy anchors are generally preferred for critical applications or when dealing with potentially compromised brick.



Anchor Material



Zinc-Plated Steel

Acceptable for general exterior use, but can rust over time, especially in wet environments.

Hot-Dipped Galvanized Steel

Much better corrosion resistance than zinc-plated. Recommended for most exterior applications.

Stainless Steel

The best corrosion resistance, ideal for coastal areas or where salt spray is present.

Anchor Size and Embedment Depth

This is the trickiest part and depends on the load calculations and the brick's strength.

You absolutely must consult the manufacturer's specifications for the anchors you choose. Every anchor manufacturer provides load tables that specify the allowable load based on anchor size, embedment depth, and the type of base material (brick, concrete, etc.).

Example (Illustrative)

Let's say you choose a 3/8" diameter sleeve anchor made of hot-dipped galvanized steel from a specific manufacturer. Their data sheet might say that for solid brick, with a minimum embedment depth of 2 inches, the allowable tension load is 500 lbs and the allowable shear load is 300 lbs. You need to ensure that the actual loads on the anchor (from the weight of the conduit, wire, wind, etc.) are significantly less than these allowable values. Use a safety factor (e.g., 4:1 or 5:1) to account for uncertainties.

Embedment Depth

The deeper the embedment, generally the higher the load capacity. However, deeper holes can weaken the brick. Follow the manufacturer's recommendations precisely.

Epoxy Embedment (Details)



Epoxy Type

Use a two-part epoxy specifically designed for anchoring into masonry. Look for products that are ICC-ES approved (International Code Council Evaluation Service). This means they've been independently tested and evaluated for their performance.

Hole Preparation

Proper hole preparation is crucial for epoxy anchors. The hole must be clean and free of dust and debris. Use a brush and compressed air to thoroughly clean the hole.

Injection Technique

Follow the epoxy manufacturer's instructions for injecting the epoxy into the hole. Most epoxies come in cartridges that require a special dispensing tool. Make sure to completely fill the hole from the bottom up to avoid air pockets.

Threaded Rod Insertion

Insert the threaded rod with a twisting motion to ensure it's fully embedded in the epoxy.

Cure Time

Allow the epoxy to fully cure according to the manufacturer's instructions before applying any load to the anchor. This can take several hours or even days, depending on the epoxy type and ambient temperature.

3. Drawing SpecificationsOn your drawings, clearly specify the following:

Conduit Type

RMC (Rigid Metal Conduit), 1-1/2"

Bracket Type

(e.g., "Galvanized Steel Conduit Clamp with Stand-off Bracket")

Bracket Spacing

(e.g., "Maximum 8 feet on center")

Anchor Type

(e.g., "3/8" Diameter Hot-Dipped Galvanized Steel Sleeve Anchor") or ("3/8" Diameter Stainless Steel Threaded Rod Anchored with ICC-ES Approved Epoxy")

Anchor Size

(e.g., "3/8" diameter x 3" long")

Anchor Material

(e.g., "Hot-Dipped Galvanized Steel") or ("Stainless Steel")

Embedment Depth

(e.g., "2" Minimum Embedment") This is particularly critical for epoxy anchors.

Epoxy (If Applicable)

"ICC-ES Approved Two-Part Epoxy for Anchoring into Masonry" (Specify the manufacturer and product name if possible)

Torque Requirements

Specify the torque value for tightening the anchors (if applicable). Use a calibrated torque wrench.

Example Drawing Note

"Provide support for 1-1/2" RMC conduit with galvanized steel conduit clamps and stand-off brackets, spaced a maximum of 8 feet on center. Secure brackets to brick wall with 3/8" diameter x 3" long hot-dipped galvanized steel sleeve anchors. Minimum embedment depth: 2". Install per manufacturer's instructions."

Important Considerations and Recommendations

Brick Condition

Critically assess the condition of the brick. If the brick is spalling, cracked, or crumbling, you'll need to use a different anchoring strategy (e.g., epoxy anchors with deeper embedment) or consult a structural engineer. Consider coring through the brick and anchoring to the structure behind it.

Load Calculations

While a full structural analysis might not be required for a small conduit run, it's essential to have a reasonable understanding of the loads involved. Consider the weight of the conduit, the weight of the wires inside, wind loads (especially if you're in a windy area), and ice loads (if applicable). Err on the side of caution.

Manufacturer's Data

Always, always, always refer to the manufacturer's data sheets for the anchors you choose. They provide critical information on allowable loads, embedment depths, and installation procedures.

Inspection

The building inspector will likely want to inspect the anchor installation to ensure it's being done correctly.

Professional Advice

If you're unsure about any aspect of this, consult with a qualified structural engineer or a licensed electrical contractor with experience in exterior conduit installations. It's better to be safe than sorry.

Access for Future Maintenance

Consider how the conduit can be accessed for future maintenance or repairs. Don't install it in a location that makes it impossible to work on.

In summary,* by selecting appropriate brackets, anchors, specifying the correct materials, following manufacturer's instructions, and clearly documenting your choices on your drawings, you can satisfy the reviewer's requirements and ensure a safe and reliable conduit installation. Remember to prioritize safety and consult with professionals when needed. Flag for review