AC adapter for PC fan - only 1 wire?

I'm going to be starting a PC grow once when my seeds arrive. I'm set on everything but had a question regarding a specific AC adapter I have.

I went to connect this AC adapter's wires to a PC fan, and I noticed this AC adapter only has a single white wire. I do have other conventional AC adapters with "throttle controls" on them that I've wired to PC fans, but they're all taken up. I figured I would ask this here, before going out of my way to grab another AC adapter at Radio Shack. Can I run the PC fan off the single white wire from the AC adapter? If so, I'm assuming I connect the white wire from the AC adapter to the red wire (hot wire?) on the PC fan.

Another thing that I've tried looking into is the amperage of this AC adapter in relation to the fan. The only thing I can seem to find is people bickering back and forth, stating that either the AC adapter having too much amperage will fry the fan, or that you want to have plenty of amps beyond that of which the fan requires, and that the adapter will not fry the fan in doing so. So who is correct? Does a high amp AC adapter = a dead PC fan? I have absolutely zero knowledge on electricity. The AC adapter puts out 12v @ 4.16 amps.


Attached are photos of the AC adapter and it's single white wire. Any input on this is appreciated.

Are you sure it puts out DC not AC? I am not sure about that drawing - line and dotted line below. Does it mark AC or DC! PC fan def needs DC. I don' t think you can fry your fan with too much amps because PSU puts out at least 12+ amps @ 12V.

You also have to check the voltages of the fan. I use one 5v cellphone charger for all four of my 120mm pc fans. My fans are 6v-7v max. So you have to check on the voltages on your fans in order to not burn them out. Hope this Helps.

First of all the wire filaments surrounding the insulated white wire core are probably the ground wire for the fan. So even though you've said you have one wire, you really have two.

Next, the amp rating of your transformer represents the maximum amount of current draw that won't overload the transformer.

If your fan draws less, that's OK; it just means the transformer has more current reserve that could be used to run something else, like a second fan.

You are NOT going to "blow up" a fan running it off a higher amp rated transformer.

They way to "blow up" a fan is to run it at too high a VOLTAGE.

Lastly, I share the concern of the other poster; its not clear to me that the transformer in question puts out 12V DC. It might put out 12V AC, which I doubt will run your fan.

Jogro said:

First of all the wire filaments surrounding the insulated white wire core are probably the ground wire for the fan. So even though you've said you have one wire, you really have two.

Next, the amp rating of your transformer represents the maximum amount of current draw that won't overload the transformer.

If your fan draws less, that's OK; it just means the transformer has more current reserve that could be used to run something else, like a second fan.

You are NOT going to "blow up" a fan running it off a higher amp rated transformer.

They way to "blow up" a fan is to run it at too high a VOLTAGE.

Lastly, I share the concern of the other poster; its not clear to me that the transformer in question puts out 12V DC. It might put out 12V AC, which I doubt will run your fan.

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This guy described it in more understandable way. I like.

Running ac power to dc fan leads to burn the adapter not the fan. But I think you should have dc adapter. This symbol looks more like DC. But better do more research, because I didn' t find exact description of ac symbol.

I really have no idea if the adapter puts out AC or DC. I figured it puts out DC because the adapter is titled "AC adapter" and puts out 12v which would be conventional with a typical AC adapter I believe... I'm not actually sure though.

In regards to the wire shielding/ground wire. I think I'm just going to avoid using this specific converter then, because I would assume non-grounded electrical devices with exposed ground wires could be dangerous, correct? I wouldn't feel safe making make-shift wire insulation with electrical tape, for the ground wire. The amperage also worries me on this thing. Being that 4 amps can easily kill you, I don't want to mess around with exposed ground wires being that I don't have knowledge on electricity other than "connect this wire to that wire". I wouldn't want to cause a fire or personal injury over something this petty.

sourtrees said:

You also have to check the voltages of the fan. I use one 5v cellphone charger for all four of my 120mm pc fans. My fans are 6v-7v max. So you have to check on the voltages on your fans in order to not burn them out. Hope this Helps.

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I actually managed to find another conventional, 2-wire AC adapter that puts out 5v @ 500mA. I'm only going to be running 1 - 2 120mm fans off this AC adapter so I'll give this 5v adapter a try.



Thanks for the input guys. Jorgo if you feel like enlightening me on my concerns above regarding the ground wire, feel free. It's always good to know.

Hahaha those 12v you can stick in your mouth and you won' t die. They will just tickle your tongue. It is like car battery. It can' t hurt you.

Def check out the voltages of pc fans. Mine all are 12V. I bet yours are too. If you will connect them to 5v they won't blow a shit. I've tried.

And that cloth wire won't work without soldering. As far as I've tried it is so when you connect audio cables for headphones.

Looks like it doesnt have a ground. At 4.6Amps tho you can run a decent amount of fans parallel.

Responding to above:

-No ground, no circuit.

-Typical computer peripherals like hard drives and fans run on 12V DC. The thing you plug your laptop into puts out 12V DC (or at least around that amount). Looking a bit more closely at the posted image, since the adapter in question is labelled "for IT equipment", I think it probably *IS* putting out 12V DC and should be fine for running a computer fan.

On safety:

-If you were actually stupid enough to stick the leads of a jumper cable from a car battery to your tongue, I assure you, you wouldn't say it "can't hurt you". Car batteries may put out low voltage, but can they put out a LOT of current (in the HUNDREDS of amps), enough to make a nasty spark and/or cause burns when the circuit is completed. Under ordinary circumstances your skin has enough resistance that 12V won't complete the circuit, but if your skin were wet it might, and there could be other circumstances where that amount of current could be harmful. Car batteries also typically contain sulfuric acid (which is highly corrosive) and lead plates (which are toxic).

-As above, the dangerous part about electricity isn't voltage, its current.

-Yes, in theory 4 amps of current could kill you, *IF* it were properly (improperly?) applied (and that generally means directly across your heart). But in practice, I don't think there is any way you're actually going to be able to draw a full 4 amps out of one of these plug in wall transformers through your body in any situation that wasn't highly contrived.

-12V DC isn't enough voltage to even penetrate your skin, which has high intrinsic resistance. You could grasp the bare output wires with your hand and not feel ANYTHING.

-As a matter of practice, I've never heard of anyone even getting a shock from one of these AC adapters, let alone a serious or fatal injury. Given how common they are, you'd have to assume that if these adapters were particularly dangerous you'd probably already know it. So in practice, I don't think you have anything to worry about. If you're worried about fire or shock, the thing to worry about is that your OUTLETS are wired to spec and that your circuit breakers are in order. Not that you're going to create a spark from this 12V computer fan and burn your house to cinders.

-There is nothing wrong with, say, covering a splice with a piece of electrical tape over a low voltage device like this.

Jogro said:

-No ground, no circuit.

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By this, you mean that I can't run the PC fan with no ground? I noticed afterwards you said it should be fine for running a PC fan.

Also, thanks for clearing up the safety issue. I had just read up a bit on amperage/voltage, and you confirm exactly what you stated.


In regards to the ground wire, which I believe is that silver wire shielding, I could try hooking that up to the PC fan's ground wire. If there are no fire hazards with low voltage fans like this I should be fine then. My house has had many run-overs with the electrical wiring, outlets, and breakers. The guy who owned the home before had no idea what he was doing and jerry-rigged the home into an electrical death trap, so it's been completely checked and fixed up. Thanks for the info.

And with "maariic"... I appreciate the help on the 5v info, but I'm pretty sure a car battery will kill you. Don't go trying to pull a fast one on me there, LOL.

I was using the term "ground" colloquially to refer to the return part of the circuit.

http://en.wikipedia.org/wiki/Ground_(electricity)

In electrical engineering, ground or earth is the reference point in an electrical circuit from which other voltages are measured, or is a common return path for electric current, or a direct physical connection to the Earth.

The use of the term ground (or earth) is so common in electrical and electronics applications that circuits in portable electronic devices such as cell phones and media players as well as circuits in vehicles such as ships, aircraft, and spacecraft may be spoken of as having a "ground" connection without any actual connection to the Earth.

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What I'm saying is that by definition you can't have a "circuit" with only one wire.

You MUST have a second wire leading from the fan to return current otherwise there will be no current flow. The return wire is called "ground" even if it doesn't physically connect to the earth.

In this case the second wire is the braided wire surrounding the inner insulated core.

For a low voltage DC circuit like this, there is no need for a third wire to go to physical earth, if that's what you are asking.

incognition! It is very good that you ask before do wiring, but car batteries only kill in Hollywood Movies! I am more than confident that you can hold those wires in hands and you won't feel anything. Same thing with wires in cars

It's 12VDC @ 4.16A

That could run a shit tone of fans and, as someone mentioned already, what may appear to be insulation is actually your ground.

Strip the middle wire and hook it up to a fan to test -- use a voltmeter if you have one.

maariic said:

incognition! It is very good that you ask before do wiring, but car batteries only kill in Hollywood Movies! I am more than confident that you can hold those wires in hands and you won't feel anything. Same thing with wires in cars

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Admittedly, Mel didn't get killed here:
http://www.youtube.com/watch?feature=player_detailpage&v=n1379iTSyHo

Yes, if your hands are dry, then you can hold a car battery leads and you won't feel a thing.

If you're grabbing them with wet hands, on the other hand, the current could be conducted across the surface of the skin causing a nasty burn.

The point isn't that a car battery is going to kill you; the point is that they most certainly CAN cause pretty serious injury in several different ways. This statement simply isn't true:

It is like car battery. It can' t hurt you.

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Don't take my word for it. Here's a published case report about a guy who got a third degree burn on his wrist when his car battery arced across his metal watch bracelet:
http://www.ncbi.nlm.nih.gov/pubmed/16006850
The injury was so bad he had to have skin grafts to fix it.

And here is a case SERIES of multiple reported eye injuries from car battery explosions:
http://bjo.bmj.com/content/66/2/141

Car batteries can output hundreds of amps... AC adapters, not so much.

All you get is a little zap -- no worse than static.

Invest in alligator leads for testing, regardless.

Jogro said:

I was using the term "ground" colloquially to refer to the return part of the circuit.

What I'm saying is that by definition you can't have a "circuit" with only one wire.

You MUST have a second wire leading from the fan to return current otherwise there will be no current flow. The return wire is called "ground" even if it doesn't physically connect to the earth.

In this case the second wire is the braided wire surrounding the inner insulated core.

For a low voltage DC circuit like this, there is no need for a third wire to go to physical earth, if that's what you are asking.

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Ok, thanks for clearing that up.

maariic said:

incognition! It is very good that you ask before do wiring, but car batteries only kill in Hollywood Movies! I am more than confident that you can hold those wires in hands and you won't feel anything. Same thing with wires in cars

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I kinda thought you were kidding at first, but thanks for busting that myth. I always thought if a car battery gets you, you got a dice roll's chance at living.

Strip the white cable. I'd hedge my bet and say there are two thin wires within that. As said above, you can't have a circuit with one wire.

InCognition said:

I kinda thought you were kidding at first, but thanks for busting that myth. I always thought if a car battery gets you, you got a dice roll's chance at living.

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Funny. I thought myself that fox is a wife of wolf because of TV. a lot of myths to bust out there. one more - petrol doesn't start to burn usually when you throw a cigarette in it. Verry small possibility that it will happen

tip top toker said:

Strip the white cable. I'd hedge my bet and say there are two thin wires within that. As said above, you can't have a circuit with one wire.

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This is a definite possibility.

Should be visible from the cut end, though.

Indeed it should, but it's often a case that people don't look at things close enough so thought i'd put it out there. As has been said, if it were just one wire then the adaptor would not function.