EB Horsman: Siemens Ready to Assemble Panelboards – RTAP Products Are in Stock & Ready When You Are
March 10, 2026
RTAPs: Siemens Ready-to-Assemble Panelboards Are Designed with Today’s Electrical Demands in Mind
When you’re trying to keep an electrical job moving, you don’t have time for long lead times or wrestling with a box in the field. Panelboards should be the easy part: available when you need them, straightforward to install, and reliable once they’re in. That’s why E.B. Horsman & Son is proud to carry Siemens Ready-to-Assemble Panelboards (RTAPs). They have an extensive inventory of RTAP products on the shelf – ready for your projects when you are!
A Faster, More Flexible Alternative to Factory‑Built Units
Ready-to-Assemble Panelboards are designed to combine the flexibility of field assembly with the consistency of a standardized platform. RTAPs are an “over the counter” solution with near-immediate availability, helping you respond to schedule changes, accelerate rough-in stages, and avoid factory orders.
Ready-to-Assemble Panelboards are also designed with today’s electrical demands in mind. The Siemens Revised P1/RP1 RTAP line includes updates that support modern distribution needs, such as expanded circuit capacity, additional main configuration options, and upgraded kits that increase customization and adaptability.
While speed is often the first reason people look at RTAP products, it’s not the only one. For engineers and specifiers working across multiple sites, they also support a consistent approach from job to job. Feed-through versions are designed to match Siemens factory-built panelboards, which helps keep installations aligned in look, quality, and compatibility when you’re expanding systems or replacing parts.
Installer-Friendly RTAP Design Keeps Projects Moving
Much of a panelboard installation comes down to wiring. Ready-to-Assemble Panelboards are designed with installer efficiency in mind, so crews can move through terminations with less clutter and fewer slowdowns. RTAP design features:
- Wiring-Friendly Design: Lay-in construction and removable lugs simplify wiring the mains and neutrals, while branch neutral connections located near breaker connections help streamline wiring and reduce clutter.
- Field-Convertible Main Breaker & Main Lug Kits (Through 400A): These make it easier to switch configurations without changing box size or adding extra cabling.
- Field Add-Ons: These support future changes by allowing subfeed breaker options (up to 250A) or feed-through lugs without using feeder breaker positions or increasing box height.
- Symmetrical Box & Interior: This supports flexible installation orientation, including rotating the interior to switch feed direction.
- Trim Options & Finish Details: The box is pre-punched for door-in-door or hinged trims, and trim details like hidden hinges/mounting hardware and rounded door corners support a cleaner, safer finish.
Ordering Siemens RTAP Products is Simple
Here is the straightforward RTAP ordering process:
- Choose your components. Select the three main parts of the build: interior, tub (box), and trim.
- Choose the main breaker kit or main lug kit (if needed). Main/subfeed breaker mounting kits can be ordered with or without breakers.
- Customize your build by adding a sub-feed breaker or feed-through lugs, plus any accessories required for the application.
- List the branch circuit breakers needed for your P1 panelboard build.
Ready to Get Your RTAP Build Dialled In?
EB Horsman’s team is ready to help, online and in-store. Send them your amperage, circuit count, and main type, and they will help confirm the right RTAP components and accessories, so that you’re not chasing parts mid-install. You can also browse and order Siemens panelboard products online.
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