Grounding Arduino — Can I connect the Uno board to the ground of mains?

Other Hardware General Electronics
1

Hi there,
I am trying to stabilise the Arduino board and I have seen that it could be connected to an earth ground (such as a water pipe).
As I don't have one where I am working I was thinking wether or not I can connect ONLY the ground of the Arduino board into a plug (via single core wire) into mains.
The plug won't have positive and negative wires attached to it.
Would this be a safe procedure?

Many thanks for your help

Best

F

2

Your instability is likely caused by some other problem. Please describe what you're doing with it, and supply a schematic.

3

You should only ever need to connect the Arduino to earth if you are doing things that require the earth as a reference point, such as radio transmissions, etc.

There should never be any need to connect it under normal circumstances.

The most common reasons for instability are:

  1. Insufficient decoupling capacitors.
  2. Lack of fly-back diodes on inductive loads for back-emf absorption.
  3. Too much current draw from an IO pin.
  4. Too much load on the regulators.
  5. Lack of debounce on buttons.

Check those things first.

4

I am building a capacitive sensor as described here Arduino Playground - HomePage
Following the advice described on that page, I have connected my laptop to the power adaptor to help stabilise the readings.
Next advice is that of connecting the Arduino ground to an earth ground, as I don't have any water pipe close to where I am working, I was wondering if I could connect the Arduino ground straight into the mains by means of a plug and a single core wire which would run from the Arduino ground to the ground to the 'E' pin on the plug, where the green and yellow ground cable usually goes. (I am in the UK using a 13A Fused plug without positive or negative wires attached)

Best

F

5

Thanks Majenko,

does this mean that it is safe enough for me to runs single core wire from the Arduino ground pin to the mains?
:slight_smile:

Many thanks

F

6

By "single core" do you mean a single connection of stranded wires, or a single wire made up of one solid metal core?

7

I mean a single wire made up of one solid metal core, which I have stripped out of a twin cable bought at Maplin earlier on today.
I am attaching two images to better describe the procedure.
Thanks!
F

Plug+wire.jpg
Plug+wire.jpg595×794 112 KB

Arduino+wireground.jpg
Arduino+wireground.jpg595×794 101 KB

8

No, that is not a safe thing to do.

Solid core cable is brittle. It should only be used in situations where there will be no motion. With motion the wire will weaken in either the plug or the terminal block where it is screwed down. If that happens in the plug, and the wire breaks, there is a good chance it will move and connect to the "Live" (or "Hot" if you're in the states) pin of the plug, and bang goes your Arduino (and maybe you too).

If you were to do this (though I can't see why you'd ever need to), the you must use stranded wire.

This is why power cables are always multi-stranded, but cables in the walls can be single stranded.

9

Hi Majenko,

many thanks for your help and all vital advice.
I will replace it with stranded wire then, the usual one (green/yellow) and will only be using it in case I will still be having erratic readings.
F

10

What are the erratic readings you are getting? What are you reading from, and what are you using to do the reading?