my case is live!

mast3r · 12 Jan 2009 at 22:00

Hi everyone!

Just wondering if it will cause any harm with my case been live, when i say live (i may be wrong and mean an earth) i hook up anything to a molex and have the red in place and the black (or yellow) touch my case it will power up.

IE, a case fan, two cables, red and black, i want to run it in 5v, i hook the red to the yellow molex and the black to any part on my case and off the fan goes, i imagine its my mainboard feeding the case.

Conan257 · 12 Jan 2009 at 22:21

Its a really rubbish idea... a better idea would be to discretely run a cable around to connect these to....

mast3r · 12 Jan 2009 at 22:24

Ah, my english is focused on Mr Baur (24 is on) so forgive me, I do not want to use my case as a ground, i am just trying to find out if the case being live is going to cause any damage to my hardware.

DigitalReaper · 12 Jan 2009 at 22:25

Your case is already connected to ground (black) through the PSUs internal grounding, the motherboard standoffs and your drive casings.

mattfinch · 12 Jan 2009 at 22:26

mast3r said:
Ah, my english is focused on Mr Baur (24 is on) so forgive me, I do not want to use my case as a ground, i am just trying to find out if the case being live is going to cause any damage to my hardware.

You're probably alright, but it's not a very good idea at best.

Mr-White · 12 Jan 2009 at 22:30

i wouldnt muck about with electricity if you don't know what you're doing, you're likely to get shocked

MW

ConTRo13R · 12 Jan 2009 at 22:33

proceed and show pictures after your 230v shock

mast3r · 12 Jan 2009 at 22:34

as it happens im a sparkie, lol. well not by trade but got my certs. just not too sure if its gowna be an issue with my other components

Blackhawk47 · 12 Jan 2009 at 22:53

had something similar happen with an old case of mine, down to the case being old i think, and i didnt mod any cables/volts or anything.

mast3r · 13 Jan 2009 at 09:54

this is a lian Li PC201 case, heavily modded, not to worry! ill live (so with the PC i hope)

Blackhawk47 · 13 Jan 2009 at 11:09

It is also possible that the psu and case fans stay on after case is off because the motherboard feels it needs to be cooler than when it was switched off. Tell me, does it happen everytime?

G-Dubs · 13 Jan 2009 at 22:16

From what I understand (been wrong before hey I'm a married man, as my wife will tell you i'm wrong a lot) a PC case is capable of acting pretty much like the -ve earth wiring circuit in a car, only that wires tend to be fed back to the PSU rather than using the body of the vehicle to conduct the -ve side of the charge. So the case itself is also a path to earth and as such can conduct DC and AC. we know a case and many of the components in it are paths to earth cos were all paranoid about static sparks when were fiddling about. I would agree that using it this way is not a good idea however as unlike a car there are components on it that are not isolated very well.

If no earth is attached to the case than no cuurent will flow in the case if however you have an earth attached to the case then you have current flowing and therefore if you have anything bridge over to the isolated side of another circuit you will form a "short circuit" you'll be able to tell when this happens as there will be a loud BANG followed by smoke and a bill

Also 12v hurts and 240 hurts a lot, like puts you on the other side of the room, and is very capable of killing you, but as a sparkie you'll know that and probably most of the above.

mast3r · 13 Jan 2009 at 22:30

City and Guilds say im a sparkie on paper! haha, i hate elctircs

Many thanks for the input guys.

Sayso · 15 Jan 2009 at 20:47

bah 240V is for girls..try a nice 440V blast that bloody hurts or even worse get some DC in ya

i thought the case was earthed through the mobo stand offs, screws attaching the PSU etc so all you would do is short out one of your 12 volt rails?

BigBoy · 17 Jan 2009 at 00:47

Completely off topic but i have seen a live wire engineer walk away from a 10000V shock after crossing poles on a 10phaze :eek:

G-Dubs · 17 Jan 2009 at 23:24

BigBoy said:
Completely off topic but i have seen a live wire engineer walk away from a 10000V shock after crossing poles on a 10phaze

Ain't the volts that kills it's the amps, i.e. how much current flows. Static electric shocks are huge with reagrds to volts, but tiny amperages

V|per · 18 Jan 2009 at 03:03

ConTRo13R said:
proceed and show pictures after your 230v shock

G-Dubs said:
Ain't the volts that kills it's the amps, i.e. how much current flows. Static electric shocks are huge with reagrds to volts, but tiny amperages

Exactly.

5000v you can feel in a static shock, 20000v you can see, 20v could damage components, but as said above, 230v will do very little damage to you if there is relatively low amperage. wouldn't like to get shocked from a psu though, 3amps can kill, imagine a 50amp rail going through your body :eek:

gazza0371 · 18 Jan 2009 at 09:30

Your case should already be earthed via the power supply - if it isn't then I'm pretty sure the PSU is breaking a few electrical safety regulations.

So, firstly, if you connect live to the case then you'll immediately create a short and blow the fuse or something else up.

Secondly, anything that is earthed (i.e. you, the cat, dog, children) that comes into contact with the case will earth the case and possibly blow a component or the fuse.

I would also expect, but don't know for sure, that a number of your other components will be expecting the case to be earth so if it isn't then at best you'll change the supply potential to that component and it won't work properly.

Basically, don't do it - at best stuff won't work, at worst you'll damage a few components.

Bubo · 18 Jan 2009 at 10:09

mast3r said:
Just wondering if it will cause any harm with my case been live, when i say live (i may be wrong and mean an earth) i hook up anything to a molex and have the red in place and the black (or yellow) touch my case it will power up.

You claim to be a sparkie?

EsaT · 18 Jan 2009 at 10:48

No it's not live, it's ground!

If you want to run something at 5V then you'll just connect it between red and black wires of PSU. But for common high speed fans 5V is often too to low for starting them.

G-Dubs said:
Also 12v hurts

Only if you place your tongue between live and neutral wires.

V|per said:
5000v you can feel in a static shock, 20000v you can see

Dielectric strength (strike through voltage) of air is roughly around 3kV per millimeter. Air humidity affects to it and especially into formation of static electricity.
If you want to try to feel electrostatic disharge try this during dry winter weather: rub normal A4 paper against lacquered table for couple minutes (when standing/sitting on insulating surface) and then touch some metal object. (even if object isn't grounded charge gets balanced between you and object)

3amps can kill, imagine a 50amp rail going through your body

50mA AC through heart is enough to stop it.
And you can't kill yourself with PC PSU's output unless it's by sticking nails to heart (or somewhere else with low resistance) and connecting wires to nails and letting current do enough internal burns. (direct damage to organs/toxic bypoducts of burnt tissue)