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Old 06-12-2019, 12:47 AM   #1
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Default 12v, 1A Power Supply powering a 12v DC blower

Is there any realistic shock hazard for a 12V, 1A DC Power Supply powering a 12V DC blower?
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Old 06-12-2019, 02:02 AM   #2
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Technically possible.
BUT

Highly inprobable.


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Old 06-12-2019, 05:54 AM   #3
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Yes, don't put it in your mouth.
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Old 06-12-2019, 07:58 AM   #4
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It's not the volts, it's the amps that kill.
Volts is jolts but mils (mA) kills.

12W is not going to power much of a blower.
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Old 06-12-2019, 08:01 AM   #5
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Quote:
Originally Posted by Bret9971 View Post
Is there any realistic shock hazard for a 12V, 1A DC Power Supply powering a 12V DC blower?
Have you ever stuck your finger in a car cigarette lighter? 12 volt DC, sometimes 30 amps.
Does that help?
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Old 06-12-2019, 08:15 AM   #6
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I have seen people post pictures of burns from sleeping on the end of their iPhone charger. That is 5 volts I believe.

Shock? As in very painful and stop your heart? Probably not. But enough current flowing to burn you over time? Yes.
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Old 06-12-2019, 10:23 AM   #7
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Quote:
Originally Posted by MikeFL View Post
It's not the volts, it's the amps that kill.
Volts is jolts but mils (mA) kills.

12W is not going to power much of a blower.
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Originally Posted by Southeast Power View Post
Have you ever stuck your finger in a car cigarette lighter? 12 volt DC, sometimes 30 amps.
Does that help?
All these things are true, but the amount of amps that flow depends on the voltage and the resistance. So it's true that amps kill, but it takes a large enough voltage to drive a lethal current through a given resistance. 12 volts ÷ 100000 ohms = 120 microamps.

To drive 30 amps through that resistance would take 100000 ohms x 30 amps = 3 million volts.
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Old 06-12-2019, 11:34 AM   #8
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A stun gun puts out about 3 miliamps.

At around 30,000 V.

They've been known to kill people.
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Old 06-12-2019, 12:28 PM   #9
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Quote:
Originally Posted by Southeast Power View Post
Have you ever stuck your finger in a car cigarette lighter? 12 volt DC, sometimes 30 amps.
Does that help?

Nope I haven't, did it hurt a lot?

Cause any burn damage?
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Old 06-12-2019, 12:30 PM   #10
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Quote:
Originally Posted by Helmut View Post
A stun gun puts out about 3 miliamps.

At around 30,000 V.

They've been known to kill people.
I had a GF that loved playing with a cattle prod....oops wrong thread!
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Old 06-12-2019, 12:53 PM   #11
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Quote:
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All these things are true, but the amount of amps that flow depends on the voltage and the resistance. So it's true that amps kill, but it takes a large enough voltage to drive a lethal current through a given resistance. 12 volts ÷ 100000 ohms = 120 microamps.

To drive 30 amps through that resistance would take 100000 ohms x 30 amps = 3 million volts.
Well there you go throwing facts around again. What are you trying to prove?
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Old 06-12-2019, 02:17 PM   #12
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Default 12v, 1A Power Supply powering a 12v DC blower

Quote:
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Is there any realistic shock hazard for a 12V, 1A DC Power Supply powering a 12V DC blower?
I guess I'm asking about a worst case scenario. 12V supply shorts to a wet piece of metal that both hands are touching. I know, it sounds crazy. Still highly improbable?
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Old 06-12-2019, 02:29 PM   #13
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Quote:
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I guess I'm asking about a worst case scenario. 12V supply shorts to a wet piece of metal that both hands are touching. I know, it sounds crazy. Still highly improbable?
Yes, 12 V just isnt enough to drive a lethal current through someone who has unbroken skin. But there is always the possibility of the high voltage side faulting to the low voltage side.
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Old 06-12-2019, 03:38 PM   #14
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Think about this. If hand to hand contact with 12VDC was enough to shock you, people would be a LOT more careful with car batteries.

From this National Institute for Occupational Health and Safety report



https://www.cdc.gov/niosh/docs/98-131/pdfs/98-131.pdf

Quote:
Under dry conditions, the resistance offered by the human body may be as high as 100,000Ohms. Wet or broken skin may drop the body’s resistance to 1,000 Ohms.


and also



Quote:
High-voltage electrical energy quickly breaks down human skin, reducing the human body’s resistance to 500 Ohms.


I am not sure what that means - the resistance drops once it starts shocking you? I don't know. Let's use 500 ohms just out of curiosity. The current is what does the damage; the current is of course is related to voltage and resistance per Ohm's law.



I = V/R = 12 / 500 = .024a = 24ma


That is enough to hurt you. If it was under 6ma you might call it safe.
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Old 06-12-2019, 03:45 PM   #15
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Default 12v, 1A Power Supply powering a 12v DC blower

From another point of view. A friend was disconnecting his 12 volt car battery, positive first (whoops).

His wedding ring was on the bare part of the wrench and it touched the car body. The ring melted all the way to the bone in an instant. Had to have surgery to get it removed.

Obviously there was no fuse at that point in the wiring, but I can imagine a 30A fuse allowing almost the same result.
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Last edited by Service Call; 06-12-2019 at 06:29 PM.
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Old 06-12-2019, 04:09 PM   #16
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Quote:
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I guess I'm asking about a worst case scenario. 12V supply shorts to a wet piece of metal that both hands are touching. I know, it sounds crazy. Still highly improbable?
Well since electricity takes ALL paths (don't believe the lore about shortest path; it's not true) and since metal has lower resistance than you, most of the energy is going through the metal.

Another thing to remember is electricity goes from a source, through a circuit, and back to the source. By touching both pieces of metal you're part of the circuit. Touch any one piece of metal, and you're not part of the circuit.
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Old 06-12-2019, 04:19 PM   #17
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Quote:
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From another point of view. A friend was disconnecting his 12 volt car battery, positive first (whoops).

His wedding ring was on the bare part of the wrench and it touched the car body. The ring melted all the way to the bone in an instant. Had to have surgery to get it removed.

Obviously there was no fuse at that point in the wiring, but I can imagine a 30 fuse allowing almost the same result.

This is true, and it's true in a variety of things, the shock might not get you but that doesn't make you safe from the molten metal.
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Old 06-12-2019, 04:25 PM   #18
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Originally Posted by Bret9971 View Post
I guess I'm asking about a worst case scenario. 12V supply shorts to a wet piece of metal that both hands are touching. I know, it sounds crazy. Still highly improbable?


Also keep in mind here - there may be zero hazard because there's no path through you to the negative terminal. Depends if the 12V system has the negative terminal bonded etc.
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