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I'm an electronics novice and I'm working with 12V at 6.5A.

(I'm activating the power supply with a series of electro-mechanical relay switches controlled by an Arduino. The power supply lights up a series of LEDs)

If I touch a bare wire at this rating, would I sustain a serious injury?

Newbie
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    As a general rule, 12V is safe. You have to have extraordinary conditions for it to hurt or kill you. – JRE Aug 27 '19 at 16:43
  • As long as the power supply has proper isolation from mains, it is properly earthed if it has an earth pin, and you are not switching the mains voltage side of the power supply, switching the 12V side or touching it should be safe. – Justme Aug 27 '19 at 17:11
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    FWIW: You are almost certainly working with a power supply that is supposed to be _capable_ of delivering _up to_ 6.5 A at a constant 12V. The actual amount of current that it delivers will be determined by the circuit that you connect to it. (Except, if the circuit tries to take more than 6.5A, then whatever happens next will be determined by the power supply: It might shut down, it might operate at reduced voltage, it might blow a fuse, it might catch fire, etc.) – Solomon Slow Aug 27 '19 at 17:42
  • don't go touching your tongue to the 12 volts; or the back of your neck; guys in highschool would take 67 volt batteries (old tube portables) and touch to back of neck/ – analogsystemsrf Aug 27 '19 at 17:59
  • @JRE like a 12V car battery with a cold crank current of 600A and you are wearing a wedding ring and had connected the negative terminal first AND while tightening the positive the ring touches chassis –  Aug 27 '19 at 19:38

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In short 12V is safe to handle. Many power supplies have current limitation built in. If you know what current will be needed for your circuit you can set the current limit to that value. To do this set the current limit to zero amps. Short the + and - wires from the power supply together, set the desired voltage and turn up the current to the value you need plus a little bit more for margin. Then open the leads. Now you have a supply that will only provide the needed current and limit damage should a short occur.

UL lists 60VDC as the maximum safe voltage and 30Vrms for AC. If you stay below these values you should stay safe. However, if you have ever shorted a 12V car battery momentarily you know that a strong spark is created. That's because a car battery can delivery hundreds of amperes, so even when you are working at lower voltages caution and care when wiring your circuit should be observed.

Rob B.
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I want to put a point here:

'It's not the Voltage but Current that kills someone "

The current rating of your power supply is not what it will always deliver. This rating simply indicates that this is the upper limit of current which this power supply is capable of delievering. Rated Voltage is something which is constant across the output. What flows through your body is the current which is actually delivered from the supply (according to ohm's law) and not the rated one. Have a quick look at the ohm's law.

I=V/R

At 12V and typical body resistance, say, 100k ohm, the current turns out to be 0.12mA(not 6.5A). This is way too less to harm our body. Even if you measure the resistance between two points inside your mouth, say tongue, it turns out to be more than 10k ohm's, which still permits only 1.2 mA current(though it may feel like a small sweet shock but safe! )

Though it is the voltage that is the cause of current, but what actually kills you is the CURRENT.

Because your supply is able to deliver more current; in case of short circuit it will cause more heat dissipation and hence more damage before it is cut off due to some reasons. This is where you have to be careful.

Bhuvnesh
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No, it's a 12V supply 12V is safe. At 60V is the point where you should be worried, because 60V is the point where voltages are considered harmful. It's volts that kill not amps. You might feel some kind of shock (depends) but it won't be enough to harm you, human skin generally ranges in at least the kΩ's range so the most current that would run through you is in the mA range.

IPC safety standards consider voltages after 60V to be hazardous and people need to be protected.

You do need to make sure the supply doesn't short out, however, at 6A a short could cause materials to heat up and melt or spark.

Voltage Spike
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    If "it's volts that kill and not amps", why aren't people killed every day by static electricity that is hundreds or thousands of volts? – Elliot Alderson Aug 27 '19 at 16:59
  • You got me there... – Voltage Spike Aug 27 '19 at 17:06
  • @VoltageSpike it's because it's _not_ the Volts that kill. It's the amps. Volts are only important because it takes a certain amount of Volts to push a lethal amount of _milli_ Amps through your heart. How many Volts depends on what parts of your body makes contact with the circuit, how much of your skin makes contact, how wet your skin is, etc. – Solomon Slow Aug 27 '19 at 17:46
  • @SolomonSlow Yeah, I've read up on the subject and written several answers on it, I didn't want to get into the details here. IPC considers anything below 60V to be generally safe, thats good enough for me – Voltage Spike Aug 27 '19 at 17:48