Ground pi 3 to earth

[vytautasniedvaras]

Hi,

I'm working on a project that uses capacitive sensors on teensy 3.2, mutiplexed to create 96 individual capacitive touch sensors.
Initially i have had this system running on a macbook pro, using openframeworks. With the macbook i have noticed that sensors would give false reading and drift, if a non-grounded charger is plugged in to the mac, all would work fine with a grounded charger or if mac was running of a battery.

I now want to port this system on to a raspberry pi 3 and I am encountering the same problem. Is there a way to ground raspberry pi to earth?

Thanks,

[mahjongg]

True, the USB power supplies used with raspberry PI's are normally double isolated types.
When the PI is used with a (HDMI) monitor the PI will normally be grounded through the HDMI cable (if the monitor is indeed grounded, as it should).

You can connect any ground pin or point of the PI to an earth wire, a wire to a stake in the ground, a water mains, the central heating, or the ground provided by your mains sockets.
all full metal connector sockets are connected to GND on the PI, USB, Ethernet, HDMI etc.

[andrum99]

You can connect any ground pin or point of the PI to an earth wire, a wire to a stake in the ground, a water mains, the central heating, or the ground provided by your mains sockets.

For safety reasons you should not connect directly to the ground connection of your mains sockets, since in the event of a wiring fault, or a faulty device, this can be live. For the same reason you should not connect directly to a water pipe or central heating since these are usually connected to the earth of the building's electrical wiring.

My suggestion would be to buy a special grounding plug with a built in 1 mega-ohm resistor. These are used to connect anti-static wrist straps, work mats etc for electronics work. The 1 mega-ohm resistor means that if the earth does become live, there is enough resistance in the plug that you can safely touch the earth "output" on the plug with no ill effect.

[Brandon92]

A better solution would be to change your sensor in such way that there is no different in both situation.

[mahjongg]

You can connect any ground pin or point of the PI to an earth wire, a wire to a stake in the ground, a water mains, the central heating, or the ground provided by your mains sockets.

For safety reasons you should not connect directly to the ground connection of your mains sockets, since in the event of a wiring fault, or a faulty device, this can be live. For the same reason you should not connect directly to a water pipe or central heating since these are usually connected to the earth of the building's electrical wiring.

My suggestion would be to buy a special grounding plug with a built in 1 mega-ohm resistor. These are used to connect anti-static wrist straps, work mats etc for electronics work. The 1 mega-ohm resistor means that if the earth does become live, there is enough resistance in the plug that you can safely touch the earth "output" on the plug with no ill effect.

If your ground connection, water pipe or central heating isn't grounded properly, but instead is connected to the electrical wiring of your hose you have larger problems than a non proper working RPI, and you have a completely incompetent electrician, to create such a deadly scenario. you can be killed each time you try to wash your hands!

The point is to have no floating AC on your PI that interferes with sensors, placing a resistor in the ground connection therefore won't do you any good.

[davidcoton]

If your ground connection, water pipe or central heating isn't grounded properly, but instead is connected to the electrical wiring of your hose you have larger problems than a non proper working RPI, and you have a completely incompetent electrician, to create such a deadly scenario. you can be killed each time you try to wash your hands!

There is a common modern supply system (in the UK at least) where all incoming metal pipes and exposed metalwork is connected to the earth terminal, that is then connected to a common Protective Earth and Neutral ("PEN") supply conductor. While this is normally at earth potential, there is one possible (but rare) supply fault that raises the whole earth system to line potential. This is not normally dangerous, because everything in the house is at the same potential, so there is no way to get a shock. However, if you introduce a separate earth (from an earth rod), or take power outdoors, or even connect a water tap outside using metal pipe, then there can be a dangerous voltage from the house "earth" to real earth. This is why you need to consult an electrician about outdoor supplies if your supply is marked "PME" or "TNC-S".

[RaTTuS]

you also have to be aware that not all pipes round the house are metal now - when they are replaced with plastic you can get issues .....