503 Extension – Recessed Box Extension

🚀 NEW VERSION AVAILABLE: V2 is here!

If you are about to download this version, I recommend you first take a look at the new V2.

The new 503 Box Extension V2 is more optimized, more robust, and includes a modular/removable holder for WAGO 221 terminals, designed to make wiring much cleaner and tidier.

✅ Less material
✅ Reinforcements in screw areas
✅ Modular WAGO 221 holder
✅ Mountable above, below, both sides, or without support
✅ Better cable management

👉 New V2 version:
https://makerworld.com/it/models/2798563-503-box-extension-v2-modular-wago-holder#profileId-3112997

This 503 electrical box extension allows increasing the available space behind the support of civil plates (BTicino, Vimar, Gewiss, etc.).
It is useful when cables come from external conduits, when the wall has shallow recesses, or when the wiring is too bulky for the standard depth of the 503.

The extension easily mounts between the flush-mounted box and the plate support, improving cable management and allowing for a clean and tidy finish.

Features

• Compatible with standard 503 boxes
• Increases usable depth for wiring or oversized corrugated pipes
• Robust design and printable without supports
• Integrates perfectly with standard civil plate supports and plates
• Ideal for renovations, extensions, or quick corrections of existing systems

Real-world applications

The images show the extension installed in a system where corrugated pipes enter the box frontally, creating little space for the sockets and switches. The extension allows for stable mounting, a smooth closure, and a clean aesthetic finish.