USB cables are a common sight in today’s world. Most of us have them laying around our homes. We use them to charge our phones, connect to the internet, and more.
Since they are electrical devices, you may be wondering if it’s possible to get shocked by a USB cable or can it hurt you?
The answer is no USB can are limited to significantly lower voltages and currents. 5VDC will not harm you, It does not have enough juice to break through your skin resistance. Only a faulty machine can give you a shock.
But some people do report a little bit of shock from the USB mostly if that USB was connected to a computer. In this article, we will explore why that happens and further explain why USBs can not harm you.
Can charging cables shock you?
The connection inside the USB cable is well designed that will deliver a lot of amps to a low-resistance device. But you human is not a device with low resistance instead you are a device with high resistance human body has a resistance of approximately 1kOhm.
Unless there is a lot of force or a high amount of voltage ( 5V in this case) behind it the current slows down significantly when it encounters a high resistance device.
This force is called “emf or electromagnetic force”. It is measurable and the force at which electricity travels is expressed in “volts.”
To keep an electric current of let’s say 5 amps flowing through you will require a lot higher volts than 5V. Even 20 volts is far from sufficient. especially if it is 20V of DC. It will require more than that to cause any harm to you.
Take an example of a nine-volt battery that has almost twice the voltage, But you can not even feel it. People have to lick them to check if they are charged.
The same is the case with a car battery it has 12 volts. You can hold both terminals in your hand and will feel nothing. So USB cables can not shock you because there are not enough volts to push the current through your body’s high resistance.
Getting shocked by a USB cable attached to a computer
As already explained USB cables can not shock you. You will not even feel it but some people do feel a little bit of shock from the USB mostly if that USB was connected to a computer.
There are a few reasons for this.
1- Static current
If the shock occurs just once, but not when you touch again after some time, It is because of the static electricity that has built up on you is discharging through the computer’s low impedance path to the ground.
This is a more common problem when wearing synthetic clothing and touching anything that is adequately grounded( such as a tracksuit, socks on even carpet, etc). You might hear a noise or see a spark and will feel intense pain or discomfort for a second.
2-Not properly grounded
Another reason why you might feel a shock from a USB that is plugged into a computer is that the USB port or the computer itself is not properly grounded as it should normally be via the PSU’s ground pin. This can happen because of the socket with bad wiring.
In a normal case, any remaining currents would be diverted to ground with solid ground, solving the problem. But if not the current can flow through your body to the ground if you provide a path for it.
This is a serious safety hazard and you should stop using that socket until it is fixed by a qualified electrician.
I hope you found this article helpful. In conclusion, USB cables are perfectly safe if they are in good condition. They can not shock you because they are limited to only 5v volts in most cases.
There is not enough potential difference (volts) present to overcome the resistance of your body which is close to 1kOhm. This is the reason you do not feel anything by touching both ends of a 9V battery.