If the compressor is grounded and it shorts internally, shouldn't that trip the fuse? (or that other thing, dunno what it is called in english, in swedish= jordfelsbrytare)
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If the compressor is grounded and it shorts internally, shouldn't that trip the fuse? (or that other thing, dunno what it is called in english, in swedish= jordfelsbrytare)
Actually for a grounded compressor to trip the fuse it would need to be comnnsected to the buildings ground this is why it is important to never remove the third prong and always use grounded equipment, if say a vapo shoted and did not have a ground connected and it only was near the supply side of the incomming power if you were to get your hand on that and another on the system ground (water pipe, faucet, a computer case that was grounded) the potential would be 120V in the us and 220 in europe and higher in some other countries. So be careful and safe never use a cooling rig with no ground. It will kill you.
Do you mean Circut Breaker? If thats what you mean it matters if the compressor is by it self on a 120volt 15 amp breaker it might catch fire before the breaker flips!Quote:
Originally Posted by Pandrone
If it shorts to equipment ground and the equipment is not grounded to the panel it probably would not trip the circuit breaker or blow the fuse so this is the real danger of unground equipment.
As pointed out it's the body's path to ground that's the killer.
You could hold a 220v live wire, and if you were standing on styrofoam - you wouldnt even be aware it was live. The national grid pilons have bare metal cables btwn each pilon carrying 10,000+ volts, but birds can sit on em quite happily and feel nowt.
The one hand rule is something everyone should follow, without your other hand touching anything thats even remotely grounded, you reduce the risk of a current flowing across your chest.
As always, you should never work on any electrical equipment when wet - wet clothing will reduce your bodies electrical resistance by a factor of a 1000+ - which increases the current flowing by the same factor. Wet shoes will radically reduce the resistance path from your body to ground and can turn a minor shock into something lethal.
Btw - batteries pose almost no electrical shock risk..the main reason being is that they have no path to ground themselves, unlike mains electricity - so it would take you touching both terminals of the battery, one in each hand, be completely soaking wet and have about 30 volts worth for you to start approaching dangerous currents flowing across your chest.
30mA can shut down ur heart.
So we once saw in school when I was like... 16 or something :)
teacher was a 'stupid' '****' but could me true...
Please please tell your dad to stop working around household electrical circuits if that's his idea of safety. I dread to think who he's going to kill with that sort of behaviour. If working on a light switch for instance the power to the lighting circuit should be off at the fuseboard for the entire diration of the work. If you can't get it done in one go, you'll have to do without lights or fit an insulating safety cover of some sort (I find not removing the old light switch till I have a new one to hand works well).Quote:
Originally Posted by Adasi
Also with regards to ground, in my opinion you should have everything grounded, extension cords especially. Luckily plugs here are designed so they don't work without an earth pin in, though I guess you can leave it disconnected (though it's illegal to do so for most equipment).
6 Milliamps across the heart will kill you. Not 3. Not that I'd wanna feel 3 :pQuote:
Originally Posted by chilly1
30 milliamps will kill you without any possibility of recussitation.
Edit: Oops, sorry for the necropost :p I saw it in the sticky and didn't really notice. Its only a month tho hehe.
There is no one universally accepted value for Fibrillation current. It depends on frequency, fitness, gender and more. Women are easier to electrocute, and mid frequency AC is most dangerous because its close to the frequency your heart naturally repolarizes at. Its just plain bad luck that the 60Hz power almost exactly matches the heart rate of the average person.
Generally the clinically accepted value is 75 to 200mA through the chest for macroshock fibrillation. As an engineering rule of thumb, you design so that theres no chance of going with 2 orders of magnitude of that value. That way from a legal perspective you're in good shape if a patient using your device drops a hair drier in the bath tub and kills themselves. Otherwise you're potientially liable for that hair drier because the patient had your ECG or pacemaker or whatever.
For microshock (current applied to the inside of the chest), the value is 20 to 200 microamps. For this reason you have to be insanely careful when you put a wire inside someone. There are people who have been electrocuted licking 9v batteries, and you sure as hell don't want to catch the tab the next time that happens.
Of course none of that really matters, since IMO any current is too much.
Fortunately, theres really no limit on how high you can be defribulated from, at least as long as you don't burn yourself to death. A defribulator will repolarize your pacemaker, and unless you're burnt to ash, it'll generally restart.
Refreshingly important notice
I gave myself a nice 230V when I was in india last summer. The electrical systems in houses there aren't as well made or protected as the better ones in 1st world countries, and old wireing with over-rated fuses is the norm. I blew a fuse when plugging a mobile A/C into my bedroom wall outlet, and proceeded to replace it. In the process, I somehow made the connection in the fuse box with my finger :(. Thankfully, I used one hand and one finger, but it was still unpleasant. I have since convinced my family there to replace the damn fuse box with a breaker box, much easier and safer.
I've been zapped by 120V. Went to unplug an extension cord at a friends house and the wire was exposed and all frayed at the plug. Man, I could feel it shoot through my nerves.
How much amps does lighter ignitors produce? Once I was so bored I was zapping myself on my left arm, found some nerves that triggers my figer movement, quite fun, lol.
Well, once I was fixing a friend's computer at his house, I went to toilet break, came back with damp hands, and started unplugging power plugs. I had my left hand on the carpet, right hand on the switch, trying to pull those big transformers out. Those transformers are hard to get off, so I inserted my fingers under it..... the index finger on my right hand felt some strong currents, so I pulled it out, and it was numb for minutes.
Anyways, does wearing anti static glove help when working with electricity? What's the safest way to discharge a capacitor and does not damage the capacitor? (Direct lead-to-lead will damage the capacitor I think)
this is not entirely true. the killer for electricity is not voltage its the Amperage. as chilly said it only takes 3 milliamps to kill you.it does this mainly by causing your heart beat to become irregular. however with the correct amperage it can stop your heart also. dc is more dangerous to an extent as it is a constant source which is harder to get loose from then AC as AC functions by the alternating peaks on the sine wave, and the change in the wave will make it easier to get loose from then DC. with that being said AC usually has the capacity to carry more amperage which is worse. it really all depends on the circuit. the main thing like chilly said is to try not to work on live circuits, always remove any jewlery watches ect before working on any electronics. i was once shocked by a CRT that had a 41KV charge on it because i had a watch on and i was a foot and a half away from it when it hit me. another thing to remember is not only can caps provide a deadly discharge but also inductors. ALWAYS use the one hand method. and as another precaution never work on electronics alone, never know when you might be needing someone to trip a breaker or pull you from a circuit. when i was in the navy i seen a guy get shocked my a 1amp circuit he seemed fine but due to the rule of if you get shocked you got and get hooked up to a EKG for 24hours hes is still alove today. cause his heart had a fluter which they were able to correct.Quote:
Originally Posted by Unknown_road
direct lead to lead can damage a cap but not usually. the correct way is to have a probe with a 1MEG OHM resistors in line with it this will discharge the cap properly.Quote:
Originally Posted by Thrilla
lighter ignitors are like a few nanoamp I think.Quote:
Originally Posted by Thrilla
anti static glove? you mean those things you should use when working with hardware? Don't exactly know witch kind you mean but I no the ones I've seen won't help.
discharging a capacitor can be done with a resistor (make sure you got one with a high enough resistance so you don't burn it). Don't touch the leads offcourse.
@tennvols: I know all that but the current through your body depends on 2 things. 1 your body's electrical resistance and 2 the current a power supply can deliver. Ohm's law states that when resistance stay's the same, higher voltage means higher current. A rule of thumb is (for normal conditions) AC becomes dangerous above 30 volt and DC becomes dangerous above 60 volt.
probably because the 30 volt is rms voltage and not amplitude. and maybe because a sine might disrupt your body's electrical signals more?
For small capacitors, I just short it with a screwdriver. I am yet to damage a capacitor this way. However for larger capacitors, it is advisable to use a resistor.Quote:
Originally Posted by Thrilla
The formula T = 1.1 * R * C, where T is the total charge / discharge time in Seconds, R is the resistance of the resistor in Ohms, and C is the capacitance in Farads, can be useful to calculate the correct resistor to use. I try to aim for a 2 second discharge time. After the resistor has been used, I then always short with a screwdriver just to be sure.
Hope that helps. :)
I'm not electrician, but I was under the impression that DC is a lot more dangerous because in the even of an electrical shock, your muscles contract, With AC because the currents alternating (i.e - to +) it's easier to overcome the contraction and let go of what ever you're holding (i.e live terminal). But with DC, it's just straight current and your muscles just contract and stay that way till the circuit breaks. I was also told that with large DC currents (not really experienced in what we're doing) it can be extremely difficult/impossible to turn off the main power switch due to the huge currents passing through it when a short occurs. These are just a few things that my old man told me when I was an inquisative kid (he's an electrician). I might not have remember it exactly, but I believe it's something like that.Quote:
Originally Posted by Unknown_road
Yea that was the impression that I always had also, that DC is more dangerous than AC for them reasons.
Was told that by my dad too, who is also an electrician. (For industrial control systems.)
I was working on an amp a few weeks ago, and somehow touched the live terminal while my hand was resting on the chassis.... I'm glad we have a breaker!
i should be dead, so many times now
the 120v shock last week
that time i touched the lamp post and got the doo doo shocked outa me
the car battery
the cap inside cameras
i used to lick electrical plugs / wires when i was little
god no wonder im so messed up
the disposable camera one is actualy pretty funny....the damned thing jammed up on me...i proceded to crush it with my hand and i got a shock like something out of this world...turns out the flash runs off a 300v cap...dont no the amperage. i ended up marketing those at my school, was great fun...
that 120v shock last week was hell....i couldent feel my own pulse...not sure if it was due to a numb hand or a weak pulse...im fine now tho
heh, gotta be safer bout this stuff
How did you get shocked from just 12v? Even a 48v phone line can not be easily felt (unless it happens to be ringing), let alone a 12v battery. Unless you cut yourself on the wiring or were soaked in sea water, I can't imagine how it happened.Quote:
the car battery
I stripped a LIVE phone wire with my teeth a while back... that hurt :(
pool...trust me its a long storyQuote:
Originally Posted by star882
I thought phones are like 3v?
Quote:
Originally Posted by star882
Sorry to necro, but AFAIK isn't those amps on car batteries friggin' huge? It could be possible to be electrocuted by car bat right?