Connecting Inprojal push buttons to Ampy: switching and dimming lights and loads in your camper

Inprojal push buttons and switches are fitted in a great many motorhomes and self-builds. The good news: you can keep them. With Ampy, your Inprojal push buttons switch and dim lights, the water pump, fans and other loads, and everything also appears in the dashboard and on the SmartKnob. Here you will find out how to connect the push buttons correctly, what to set in the dashboard and what to look out for.

Push button or switch: the small difference

From the outside they often look the same. Inside, though, they work quite differently:

• A push button is like a doorbell. It only makes contact while you press it and then springs back by itself. The technical term is a normally open contact without latching.
• A switch is like the light switch at home. It stays in the position you put it in, on or off.

Both work with Ampy. Our recommendation is still the push button: only with a push button can you dim right at the wall, because dimming works by pressing and holding. A push button costs no more, so you are not closing off any options.

Why Inprojal is so common in campers

Inprojal is a manufacturer from Lüdenscheid in Germany that makes switches, push buttons, sockets and frames specifically for fitting in motorhomes and caravans. The elements are very shallow, which suits thin furniture panels. There are complete ranges such as System 10.000 and System 20.000, in which push buttons, switches, sockets and frames match visually, and you can buy them from many camping retailers. That is exactly why so many vehicles already have Inprojal fitted, and why many self-builders pick it straight away when building their furniture.

Typical Inprojal elements you will come across include:

• simple push buttons with one normally open contact
• series push buttons with two normally open contacts and one common terminal
• the flat 4-way push button 30420 with four buttons side by side
• on/off and two-way switches with latching
• versions with a built-in indicator light or permanent illumination

How Inprojal push buttons and Ampy work together

Traditionally, the current for the lamp flows straight through the switch. With Ampy it is different: the light is connected to one of Ampy's outputs, and the push button only sends a small signal. When you press it, the push button connects the push button input to ground, Ampy notices and switches the output. So no load current flows through the push button wire any more, only a tiny switching signal. That is why two thin wires are enough.

Ampy has six outputs, and each output has its own push button input. The push button wires go into removable two-pin plugs with spring terminals, one per output, each sitting right next to the output it belongs to. Each of these plugs has two connections: one for the push button signal and one for ground, GND. The ground connections of all six plugs are linked inside Ampy.

The pins are not labelled, but you do not need a label. Remember one simple rule: the left pin is always pin 1, whichever way round you hold Ampy. The push button signal goes on pin 1. The right pin is pin 2 and is always ground (GND).

Each load is connected to its output, its push button to the plug right next to it. Looking at a plug from the front, the signal is always on the left and ground on the right. Tap to open the diagram at full size.

What you need

• an Ampy, connected as described in Connecting Ampy
• your Inprojal push buttons or switches, ideally without built-in illumination
• two thin wires per push button, five for the 4-way push button
• the SmartKnob and the dashboard for setup

Incidentally, Ampy responds to its push buttons even without any setup. That is handy for a first test straight after installation.

Connecting step by step

1. Power off: switch off the leisure battery at the main isolator before you start wiring.
2. Light or load to Ampy: connect the light to the Ampy output you want to use. The cable to the light no longer runs via the push button.
3. Wire the push button: run two wires from your Inprojal push button to Ampy. One goes to the signal connection (left pin), the other to GND (right pin) on the plug right next to this output. With a simple push button it does not matter which wire goes where.
4. Fit the plug: you can prepare the plugs comfortably at the table and simply plug them in inside the vehicle.
5. Power on and test: a short press on the push button switches the output on, a second one switches it off again.

This overview shows which Inprojal terminal goes where. Terminal markings can vary from model to model, so always check the marking on your push button or its instructions.

Inprojal element	Terminal on the push button	Where on Ampy	Setting in the dashboard
Push button, 1 normally open contact	the two contact terminals	one to signal, one to GND of the matching output, order does not matter	Pushbutton
Series push button, 2 normally open contacts with common terminal	common terminal	GND	Pushbutton
	output of the first contact	signal of output A
	output of the second contact	signal of output B
4-way push button 30420	common terminal	GND on any one of the plugs	Pushbutton
	terminal for buttons 1 to 4	each to the signal of its own output, for example outputs 1 to 4
On/off or two-way switch	input (L or 1) and make contact (2)	input to GND, make contact to signal. The third contact stays free	Toggle
Push button or switch with indicator light or permanent illumination	contact and LED	check with us first, see below

Connecting the Inprojal 4-way push button

The 4-way push button 30420 is a popular central push button for the entrance. It has five connections: one common and one each for the four buttons. Connect the common terminal to GND, on any of the six plugs, because ground is the same on all of them. The other four wires go to the signal connections of four different outputs. Each button then switches its own load, for example the ceiling light, kitchen light, ambient light and water pump.

According to retailers, the 30420 has a 5-pin RAST 2.5 connector and is designed for small signal currents of up to 50mA at 12V or 24V. That is a good match, because Ampy only needs a tiny signal. Which of the five pins is the common one is shown in the push button's documentation. Alternatively, a continuity tester helps: the common pin is the one that shows continuity whenever any of the four buttons is pressed.

Several push buttons for the same light

Want to switch the light at the entrance and by the bed? You do not need two-way wiring for that. Simply connect a second push button in parallel with the first: signal to signal, ground to ground, both on the plug of the same output. Pressing either of them switches the same light. You can read more in Switching one light in the camper from two places.

Setting it up in the dashboard

So that your push button does exactly what you want, you create a widget for the output. It takes about a minute.

1. Open the space: for lights this is Lighting, for the pump Water, for fans, the fridge and other loads Appliances. Tap Add Widget there.
2. Choose the function: for a light, for example Light (Switch & Dim), for the pump Water Pump, for other loads Appliance.
3. Choose a module: your Ampy.
4. Choose Port: the output the light or load is connected to.
5. Configure Channel: enter a name. For a dimmable light, switch on Dimmable under Dimming.
6. Register the push button: open Advanced Settings. Under External Switch, switch on Connected and choose either Pushbutton or Toggle as the Switch Type.
7. Done: tap Create Widget.

If Dimmable is on and Pushbutton is selected, the dashboard shows the hint "Hold button to dim". If you choose Toggle for a dimmable light, it points out that toggle switches cannot dim externally.

You can change everything later via the widget's menu under Settings and confirm with Save.

Important: as soon as a widget has been created for an output, Ampy only listens to the push button if Connected is switched on under External Switch. This way, open inputs without a push button can never trigger anything by accident. If your push button stops responding after setup, this is almost always the reason.

Whatever you switch at the push button shows up in the dashboard straight away, here the water pump on an Ampy output with voltage, current and power.

What your push button does

With a push button on a light that is set to Dimmable:

• Short press: light on or off. When switching on, the brightness you last used comes back.
• Press and hold: after about half a second the light becomes smoothly brighter or darker for as long as you hold. The next time you hold, it goes the other way. At the very top and the very bottom, Ampy reverses the direction by itself. Holding never switches the light off completely, that is what the short press is for.
• Press twice in quick succession: all lights in the vehicle go off together, including those on other modules. If your light was off before, all of them come on instead. Ideal as a good-night button by the bed: double tap, and everything is dark.

With a push button on the water pump, a fan or another load, every short press simply switches it on or off.

With a switch, the output follows the switch position: switch on, load on. Dimming is not possible with a switch.

Ampy dims up to 5A per output, which is enough for reading lamps, spots, kitchen and bathroom lights and white LED bars. More on this in Switching and dimming lights in the camper with Ampy. Lamps that the manufacturer says are not dimmable go on an output without Dimmable and are only switched on and off.

Push button, SmartKnob and dashboard are equal and always in sync. If you switch at the push button, you see it on your phone straight away, and vice versa.

Illumination and indicator light on the push button

Some Inprojal push buttons and switches have a built-in LED, either as permanent illumination for finding them in the dark or as an indicator light. Ampy has no dedicated output to drive such a push button LED. Whether your light is currently on can be seen in the dashboard, on the SmartKnob and on the status light directly on Ampy: blue means on, red means off.

On illuminated models, the LED needs its own supply, and depending on the model it shares a terminal with the push button contact. However, no voltage may ever be applied to Ampy's push button input. If you want to connect an illuminated model, send us the exact item number beforehand via the contact form, and we will look at the wiring together with you. To get started, unilluminated push buttons keep you on the safe side.

Tips and safety

• Never positive on the push button input: the push button only connects signal and ground. A positive cable that used to go to the old switch must be disconnected.
• Only wire with the power off: switch off the leisure battery before any work.
• Fuse the main cable properly: Ampy's outputs have electronic fuses, but you still fuse the supply cable to Ampy like any main cable. What is mandatory and which cable size fits is explained in Fuses and cable sizes.
• Route push button wires separately: where possible, do not bundle the thin push button wires tightly alongside thick load cables, especially dimmed ones. This keeps the signal clean.
• Fuse tripped: if an output's electronic fuse has tripped, the push button will not switch it back on either. The output only responds again once you reset the fuse. How to do that is explained in Electronic fuses: adjust instead of replace.

If a fuse trips, the SmartKnob shows straight away which device is affected.

Inprojal push buttons on Lighty

Lighty is designed for coloured ambient light and LED strips with several channels. Inprojal push buttons work there too, for example the 4-way push button on Lighty Extension. How that works is shown in More push buttons with Lighty Extension. Which push buttons and lights work overall can be found in the compatibility list for lighting and push buttons.

Further reading

• Connecting Ampy
• Setting up Ampy's outputs: every output becomes a widget
• Switching and dimming lights in the camper with Ampy
• Compatibility: LED strips, push buttons and wireless switches