The short answer: some KNX keypads are made for a standard US single gang box. Most European designs need the European backbox they were made for, or a mud ring for European size products. Choose the keypad first, then plan the box before rough in, while the walls are still open.
Why a European switch does not simply drop into a US box
A US single gang box holds a device with two screws, 3 9/32 inches (83.3 mm) apart, in a rectangular opening. Most European switches are made for a round flush box with fixing points 60 mm apart. JUNG, for example, builds for the European flush box standard DIN 49073.
So the screws do not line up, and the opening has a different shape. A wall plate that covers the hole can still sit on fixing points that do not match.
KNX itself does not decide this. KNX is the system the devices talk on, and each manufacturer decides how its keypad mounts. Two keypads from the same brand can mount differently.
Three ways to make it work
1. A keypad made for US boxes
The simplest route. Our US KNX keypad fits a standard US single gang box with a Decora style wall plate, with 2, 3 or 6 buttons. The GVS S Series and the Lithoss Opera frame also mount on a US single gang box.
2. A mud ring for European size products
A mud ring sits on a 4 inch square US box and sets the opening at the finished wall. The Basalte 0090-04 mud ring gives a round opening with European fixing points. We use it for single European frames, for example JUNG and Basalte.
3. The European backbox itself
In drywall, a hollow wall box such as the KAISER 9064-02 goes into a 68 mm hole and is 62 mm deep. Our JUNG designer adds hollow wall boxes in 62 mm or 49 mm depth, one per gang.
Three numbers matter: the hole you cut, the distance between the screws, and the depth behind the wall. A 68 mm hole and 60 mm screw spacing describe different things, and a deeper box gives more room but does not move the screws.
What to check, brand by brand
| Brand | US mounting options |
|---|---|
| JUNG | Made for the round European box. Mud ring for single frames, hollow wall boxes for every size. |
| Basalte | Made for the European box. Basalte mud ring for US walls, and flush mount sets for a seamless look. |
| CORE | Made for the European box. Mud ring and hollow wall boxes available. |
| Lithoss | Opera mounts directly on a US single gang box. A single Original frame fits a US 2 gang box with a Lithoss mud ring. Circum uses a European round box; a US box is checked per project. |
| GVS | S Series fits a US single gang box. Waltz, V Series and Glass Sensor use the European box, which we also supply. |
| Zennio | Please ask us about the exact model. |
| US KNX keypad | Standard US single gang box with a Decora style wall plate. |
This can change from one model to the next, so always confirm the exact product before the box goes in.
Plan it before rough in
- Choose the exact keypad and get its installation instructions.
- Confirm the box and any mud ring or mounting part.
- Check the wall: drywall layers, tile, stone or wood paneling all change the depth and the finished surface.
- Fit one complete sample with its cover before the detail is repeated through the house.
- Give the approved detail to the electrician and the drywall team.
For double and triple frames, follow the manufacturer’s spacing. European multi gang frames do not automatically line up with a US 2 or 3 gang box.
Renovating an existing home?
Look at the wiring as well as the box. An existing switch box usually has 120 V wiring, while a KNX keypad connects to the KNX bus cable. A box that fits does not solve the wiring, so your KNX System Integrator plans where the bus cable goes.
A good fit is not an approval
Fitting the box is only part of the job. Some products carry UL or ETL marks and others do not, and buying a product does not guarantee that your project will be approved. Low voltage does not automatically mean NEC Class 2 either.
Please check the power supply, the wiring method and the product with your electrician and your local inspector, known as the Authority Having Jurisdiction (AHJ), before you order. We can share the certificates or data sheets we have for the products you choose.
Plan it with Smart Building Solutions
Send us the keypad you like, a photo or drawing of the box, and the wall finish. We will help you find the right mounting parts and documents, and work through the detail with your electrician.
Frequently asked questions
Do European KNX switches fit a US single gang box?
Usually not directly. European switches use fixing points 60 mm apart, a US box uses 3 9/32 inches (83.3 mm). Use a keypad made for US boxes, a mud ring for European size products, or the European backbox.
What is a mud ring?
A plate on a 4 inch square box that sets the opening and the fixing points at the finished wall. A mud ring for European size products gives a round opening for European switches.
Does a deeper box make a European switch fit?
No. A deeper box gives more room for the device and the cable, but it does not change the screw spacing or the shape of the opening.
When should we decide on the backboxes?
Before rough in, while the walls are open. Changing a box after drywall can mean cutting and patching a finished wall.
Can I put a KNX keypad in an existing switch box?
Sometimes the box fits, but the wiring is different. A KNX keypad connects to the KNX bus cable, not to the 120 V switch wiring, so plan the cable with your KNX System Integrator.
Can you help my electrician?
Yes. Send us the keypad model, a photo or drawing of the box and the wall finish, and we will share the mounting details and documents we have.
Product details can change. Always check the current installation instructions for your exact model.