Stray voltage and wife rage - help a guy out?
- Thread starter Jonas Bergkvist
- Start date
- Tagged users None
redfishbluefish
Stay Positive, Stay Productive
Staff member
Super Moderator
Reef Squad
Partner Member 2024
Excellence Award
Article Contributor
NJRC Member
Hospitality Award
My Tank Thread
I didn't catch that either....they use 230V, 50Hz with two prong outlets:
Paul B
10K Club member
Excellence Award
Reef Tank 365
Reef Of The Month
Article Contributor
Rock Pool Reef Keepers
I actually had to go to pole climbing school in the Army. That was a waste.
edd59
Well-Known Member
yea me and the other hundreds of mechanics i worked with got lucky. i have wrenches with weld marks on them from shorting while i was holding them and never got shocked. even with heavy equipment that run 4 12v batteries. never seen or heard another mechanic ever getting shocked. im speaking from alot of hands on experience. maybe we were all lucky.
The bell system one was more entertaining. People from directory services decided to become installers because it's a higher pay grade. But a 28 foot company approved fiberglass ladder still weighed 78-82 pounds. They had to get it off a van, put it up, take it down and put it back with a climbing belt on. People that had been sitting taking phone calls for any length of time rarely passed and the short thin people had no chance.I actually had to go to pole climbing school in the Army. That was a waste.
That was before you even got to pole climbing. Few of the ones that could barely pass the ladder could get their own body weight up a pole.
I am sure it was different in the army with young fitter people.
My advice to get an electrician still works.
And all it takes is a route from you to something else conductive for you to not be lucky. You already stated the current will weld metal, I’ve seen it to, so how does that scream safe to you? If you are insulated properly you are fine but that’s not always the case. I really don’t know why you are arguing that if current from a 12 volt battery passes through you it’s safe. Anyways it’s not even relevant to this thread so I’m going to stop here.
OP
OP
Jonas Bergkvist
Active Member
Hi! We use 230v here. Your right, the sockets and what not electrical thingies is a bit different. Maybe i can look at the adapters and see wich one of them uses 110 volts? Good you mentioned it. I will book an electrician tomorrow and see if he can help me out. I’ve been crazy busy past weeks
edd59
Well-Known Member
im talking from expreriance. i dont know where your information is coming from. do your research its in black and white that a car battery will not shock you, too much resistance in your skin
Simon_M
Active Member
This is quite a common problem with switched mode PSU e.g. a 12V 1.5A DC power brick that connects to the mains and provide 12V to equipment. They can have a two or 3 pronged plug and usually indicate that they are double isolated e.g. a plastic case. The issue is how they work internally.
With a multimeter, I can measure AC voltage e.g. in UK it's 230V AC 50 Hz. Often I measure it and it's 247V AC and 50Hz. That's OK because there is a tolerence e.g. +/- 10%. My multimeter also displays the frequency and it invariably also shows 50 Hz. On DC it doesn't show anything, that's why it is important to have it switched to AC.
The output of a modern switched mode PSU will measure 12V (or slightly higher) using the same multimeter if it is set to measure DC voltage. It will also often show a voltage of 80V or something that is approaching half the mains voltage.
Unfortunately that is quite normal and is a function of the design. All PSU use an isolating transformer to transfer power from the "hot" mains side to the "isolated" output side. If the multimeter can measure resistance then you can see that either pins of the input is not connected to the output. It indicates a very high DC isolation between the input and the output.
In a switched mode PSU the mains voltage is rectified to DC and a switching circuit drives a transformer. It doesn't switch it at 50 Hz but rather alternatives the supply at a much higher frequency e.g. 20 KHz. Driving a transformer at high frequency can be very efficient so it can be small, won't get too hot and is cheap. The issue is that this circuit is electrically rather noisy and there would be radiating electrical noise (RFI). To fix this the design connects the "hot" and "isolated" side together using special capacitors. You will often see special blue capacitors that have a UL rating or similar on them.
The capacitors may be connected from the output "isolated" side back to the "hot" side on both the live and neutral and sometimes the earth pin if it is not plastic. Electrically this forms a "potential divider" and so the voltage is almost mid way between neutral and live and so typically is 80 - 90V. On my multimeter the frequency shown isn't the mains 50 Hz, but is the switching frequency e.g. 20 KHz. On this equipment I may get a small buzz. If I connect the PSU output through the multimeter to a grounded outlet there is a small AC "leakage" current e.g. 50 uA.
Typically, you notice this when standing on a concrete/tiled floor but not on a wooden/carpeted covering and only when you initially are connected. Afterwards the circuit changes (you are a resistor) and you no longer get "zapped".
Some designs are better than others but it is normal and by (not so good) design. Some "Cheap" PSU units don't have the problem because the manufacturer "forgets" to install these components after the units are tested/certified but when produced. They are electrically noisy and would fail RFI tests, if retested. One issue is that the same PSU is sold across the world and has to work with different electrical standards and the design works better in some countries than others. My electric supply (Uk houses in last 30 years) is unique in that there is no real earth and my mains has L and N where the N is also the E and there is no physical earth or connection back to the Supply Company.
With a multimeter, I can measure AC voltage e.g. in UK it's 230V AC 50 Hz. Often I measure it and it's 247V AC and 50Hz. That's OK because there is a tolerence e.g. +/- 10%. My multimeter also displays the frequency and it invariably also shows 50 Hz. On DC it doesn't show anything, that's why it is important to have it switched to AC.
The output of a modern switched mode PSU will measure 12V (or slightly higher) using the same multimeter if it is set to measure DC voltage. It will also often show a voltage of 80V or something that is approaching half the mains voltage.
Unfortunately that is quite normal and is a function of the design. All PSU use an isolating transformer to transfer power from the "hot" mains side to the "isolated" output side. If the multimeter can measure resistance then you can see that either pins of the input is not connected to the output. It indicates a very high DC isolation between the input and the output.
In a switched mode PSU the mains voltage is rectified to DC and a switching circuit drives a transformer. It doesn't switch it at 50 Hz but rather alternatives the supply at a much higher frequency e.g. 20 KHz. Driving a transformer at high frequency can be very efficient so it can be small, won't get too hot and is cheap. The issue is that this circuit is electrically rather noisy and there would be radiating electrical noise (RFI). To fix this the design connects the "hot" and "isolated" side together using special capacitors. You will often see special blue capacitors that have a UL rating or similar on them.
The capacitors may be connected from the output "isolated" side back to the "hot" side on both the live and neutral and sometimes the earth pin if it is not plastic. Electrically this forms a "potential divider" and so the voltage is almost mid way between neutral and live and so typically is 80 - 90V. On my multimeter the frequency shown isn't the mains 50 Hz, but is the switching frequency e.g. 20 KHz. On this equipment I may get a small buzz. If I connect the PSU output through the multimeter to a grounded outlet there is a small AC "leakage" current e.g. 50 uA.
Typically, you notice this when standing on a concrete/tiled floor but not on a wooden/carpeted covering and only when you initially are connected. Afterwards the circuit changes (you are a resistor) and you no longer get "zapped".
Some designs are better than others but it is normal and by (not so good) design. Some "Cheap" PSU units don't have the problem because the manufacturer "forgets" to install these components after the units are tested/certified but when produced. They are electrically noisy and would fail RFI tests, if retested. One issue is that the same PSU is sold across the world and has to work with different electrical standards and the design works better in some countries than others. My electric supply (Uk houses in last 30 years) is unique in that there is no real earth and my mains has L and N where the N is also the E and there is no physical earth or connection back to the Supply Company.
Last edited:
Never test to ground. Test to neutral. I had same thing had 75 V AC. Which is what you test for . Was my power head.After getting zapped in my finger a couple of times i got myself a voltage meter. Not even sure i'm reading it right. I thought I'd post it here and see what you guys think.
Short back story: my skimmer overflowed and i guess two liters came out in the aquarium stand and out on the parquet floor. Floor is a bit ruined, but my wife hasn't seen it yet
After a day i got another zap. Measured again and nothing....but all of a sudden i got a reading once again. Discovered that when i DID get zapped i stood on the moist parquet. So i measured from the moist spot to various things and YAY.....i still have a problem.
Does this mean that the electricity comes from a pump or something, and when i put my finger in the water the electricity passes through me and down somewhere? Because i act as a ground? Fish seems unaffected - i guess the aquarium is isolated.
I guess next thing is to pull my return pump and work from there. I so hope it's not that pump. Does my measurement mean that it's an AC pump that's broken?
Any help/suggestions is much appreciated - i don't want to get electrocuted and i feel uncomfortable doing this. Wait, wife floor-rage-death or electrified-to-death? ;Blackeye
Voltage DCV
Wood floor to socket ground = 0,3v
Tank water to socket ground = 0,001v
Tank water to wood floor = 1v
And here comes the fun part:
Voltage ACV
Tank water to socket ground = 7,6-9,3v
Wood floor to socket ground = 80,5v
Tank water to wood floor = 110v
Sorry but it wont the voltage has to have a path to ground GFI measures amperage in, to amperage out of a load if there was a leak to ground then the amps out would be less then GFI trips
Would not agree that it is a ground issue at all. It is potential energy like power on one side of an open switch so zero on other side. He is making the circuit is all it is . He is lucky he did not make a good ground< There is an electrician on the site now that has kindly offered his advice. Should talk to him. Don't know his call sign sorry
Tankkeepers
Valuable Member
Direct current DC is more dangerous then alternating current AC
If you think 12 volts won't shock you go grab a car battery and place a hand on each terminal then have your significant other come tell us how long it was before your heart stopped
Tankkeepers
Valuable Member
That would be becouse you didn't ground yourself to anything the wre nch carried the current
Grab ahold with sweaty hands as most of us have when working a metal bumper or frame on the car then grab that same wrench and touch it to the positive side while holding the wrench and with the other hand holding the frame etc and once you do this you act as the circuit and this will shock and possibly kill you
For having 30 years experience you sure don't seem like you know what your talking about spreading false information that can be deadly to someone who does not know any better
12v is usually not enoff volts to penitrate our skin which is why alot think it's safe it is not
Have a small cut or nick on your hand now that's all bad or any direct path that bypasses the resistance of our skin and your dead
Can't find the story but awhile ago a guy was killed demonstrating how safe grabbing a car battery at 12v is to a class of kids
Was not so safe that day
Tankkeepers
Valuable Member
You go ahead and belive that
iv been shocked enoff times by a 12v car battery to know better
Wish I could find the news article from awhile ago
A guy died diminstraing how safe a car battery is to touch in front of a school assembly
Was not so safe that day as that guy is toasty
Just becouse 12v has a hard time getting threw your skin does not mean it won't still kill you when it does
Tankkeepers
Valuable Member
jacquesm on April 28, 2012 | next [–] > It is perhaps worth noting that 12/24V DC is just as deadly as 120/240V AC. No it definitely isn't. > There's naught deadly in voltage, it's the wattage that electrocutes you. In fact, if you want to be precise, it is the current (Amps) that kills you. The reason why 24V isn't nearly as deadly is because at the resistance your skin normally has the current will be low enough that it does not get dangerous. Up to 48V is considered a 'safe' voltage, but you can definitely feel it and DC is far more dangerous than AC (because with DC your muscles contract and stay contracted so it can be very difficult to disengage from the source). If you lost muscle control over 6V then likely there were some other circumstances in play, for instance you could have been poking around in a spot where your skin had been breached or you may have had sweat or some other salty solution on your skin. Real danger starts around 80V for DC and 150V for AC. Yes, you can get electrocuted at lower voltages but you'd have to really work at it. Most high voltage circuits that you are likely to come in contact with have an internal resistance that is high enough that they can not source a high enough current to do damage, that's why you perceive high voltages as safe. But if a high voltage circuit is beefy enough that it can supply a couple of hundred milli-Amperes you're as good as dead because at that voltage your skin is no longer a strong enough barrier See If you lost muscle control over 6V then likely there were some other circumstances in play, for instance you could have been poking around in a spot where your skin had been breached or you may have had sweat or some other salty solution on your skin. So as I said 12v can kill just by reducing resistance on your hands yes dry its high but sweeting as most do when working in the garage is a whole diffrent story I get real sick and tired of people who don't really know what they are talking about saying 12v is harmless And if you really want to go the 12v dc is harmless then by the same logic so is a 110 v ac Neither are safe or harmless and both if given a chance will kill you |
Close enough for me to not muddy the waters but you can get frozen easily with 120 I as you said have been shocked with 24V but again the amps as you said is the killer IE the resistance of your body in all sorts of scenarios I forget the actual amp level minimum I can look it up but I think it is .005 amps. That means you are the load in this case resistive like a stove element to your dc comment as compared to a motor which is inductive ( pulse driven )
Similar threads
-
- Poll
