When I was in the lab at university, I fell for the old throw a charged capacitor and see if she'll catch it joke - that hurt! I've had various minor shocks in my over 30 years of being in the industry, usually because of lack of concentration and failing to stick to a routine. One I do remember from years ago was brushing my hand against the top cap [anode] of a PL509 in a colour TV I was repairing, that made my eyes water!
An old Knight amplifier running 7189 tubes (NOT an EL84) in push-pull. I was a freshman in college in 1989, and dad gave me the amp for my dorm room. Cool ... tubes ... but they were gassy and glowed blue. I stripped down the amp and upgraded the capacitors (they were rotting). Something wasn't working right, so I flipped the chassis over to look. I hit the transformer's secondary, totally unloaded. It was about 840VAC (peak to peak). It hurt.
Thank goodness for zero crossings! AC is your friend!
OPTs were cheap trash, the output ran in pentode mode, tons of global feedback, epitome of a 1960s design, but it was a good dorm room amp.
Thank goodness for zero crossings! AC is your friend!
OPTs were cheap trash, the output ran in pentode mode, tons of global feedback, epitome of a 1960s design, but it was a good dorm room amp.
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Zap!
Several, but one bad recent.
In school I took my dead B&W TV set to class.The instructor (Foolishly) was poking near the rectifyer tube saying "I should be getting shocked here", perhaps he knew right off it wouldn't be active...upon repair I took it home, opened it up, took a 12 Gauge wire, screwed in into the center screw on a 110 outlet. Knowing it was ground I marveled at the arc my wire was making...the screen shrinking with the arc......stupid me, dodged a bullet there.
Recently my brother-in-law had an electric fence module for his Pig-Farm. The old one went down (Bad SCR) so he got one rated for 30 Km @ 5Kv (His run was 300Ft). Way big. I set the thing up & told him of the shorting out can occur with tall grass on the wire. Testing lines was no problem till I noted that humans with their shoes insulates the effects. So stupid me takes of his shoes & touches the line with the wet grass in stocking feet.........3X the effect & painful. By far the worst was when we got down here four years ago...I was tooling around the yard & saw what appeared to be some electrical tape sticking out of a wall....two curls of E-tape......like it had been exposed for years as it unwinds with time......."What is tha............"
220VAC............I hate that........the buzz effect as the 50 Hz roils thru your body.
___________________________________________________Rick.........
Several, but one bad recent.
In school I took my dead B&W TV set to class.The instructor (Foolishly) was poking near the rectifyer tube saying "I should be getting shocked here", perhaps he knew right off it wouldn't be active...upon repair I took it home, opened it up, took a 12 Gauge wire, screwed in into the center screw on a 110 outlet. Knowing it was ground I marveled at the arc my wire was making...the screen shrinking with the arc......stupid me, dodged a bullet there.
Recently my brother-in-law had an electric fence module for his Pig-Farm. The old one went down (Bad SCR) so he got one rated for 30 Km @ 5Kv (His run was 300Ft). Way big. I set the thing up & told him of the shorting out can occur with tall grass on the wire. Testing lines was no problem till I noted that humans with their shoes insulates the effects. So stupid me takes of his shoes & touches the line with the wet grass in stocking feet.........3X the effect & painful. By far the worst was when we got down here four years ago...I was tooling around the yard & saw what appeared to be some electrical tape sticking out of a wall....two curls of E-tape......like it had been exposed for years as it unwinds with time......."What is tha............"
220VAC............I hate that........the buzz effect as the 50 Hz roils thru your body.
___________________________________________________Rick.........
Hi Richard,
I remember that I experimented with an electric fence as well. I was a little fella and I'm told I decided to climb that fence. Failed. For some reason, the memory is pretty fuzzy.
Returning to thread ...
I've been nailed by a TV (I hate TVs). Didn't even touch the tube. One hand on the chassis (I had to reach in near the front of the tuner). Lucky for me it was dark back there. I even got to see the arc form and whack my arm. It's the involuntary muscle contractions that cause injury. That one gave me heavy bruising and a gash.
Oscilloscopes, more than once. All different models. I wonder if the engineers who designed them chuckled as they configured the focus control near the top right side on some of these. That's about 1.5 KV. Gets your attention, then you have the jitters for a couple hours. Just plain unpleasant.
Fender Twin amplifiers. Yup. They run those poor 6L6GCs hot, about 475 VDC worth of hot. When you're chasing an odd problem, discharging eventually doesn't get done. When you become part of an unintentional circuit, you tend to speak in tongues briefly. It's best not to be in a hurry.
Over the years I've suffered many self inflicted zings and zaps. Left hand in the pocket has been a life saver for me I'm sure. The shock that bothered me the most was the one I received while attending Ryerson in Toronto. My lab partner was staring off into space as I worked at putting a lab together. He came too just long enough to wonder why there was an AC cord lying on the bench. I had my back turned, so I didn't actually see him absent-mindedly plug the damn thing in. That one stung quite a bit. My lab partner had to finish putting the experiment together, but not until he explained to the prof. what had just taken place. Yup, I had the jitters again for a few hours. That lab partner I had 28 years ago or so is still a very good friend. He maintains that he doesn't know why he plugged the cord in.
Car ignition systems? Man, they sting along with the sensation of being whacked with a wooden dowel with every jolt. Not too much fun either.
The old toss the charged up capacitor thing was one of my favorite tricks. Thing is, you have to make sure the cap is a low capacitance value or it really hurts the victim. A school chum charged up an 8 uF, 450 V model to about 400 V. Chucked it at another while calling his name. Guy turns, catches the cap and gets nailed. Well, the discharged capacitor hurt more coming back. The victim not only had a great throwing arm, but he also had excellent control. The "chum" got it in the arm pit (discharged mostly now). He was only wearing a light tee-shirt. The reaction to a shock is normally the most dangerous part of the event at reasonable voltages. It certainly was in this case. 😀
-Chris
I remember that I experimented with an electric fence as well. I was a little fella and I'm told I decided to climb that fence. Failed. For some reason, the memory is pretty fuzzy.
Returning to thread ...
I've been nailed by a TV (I hate TVs). Didn't even touch the tube. One hand on the chassis (I had to reach in near the front of the tuner). Lucky for me it was dark back there. I even got to see the arc form and whack my arm. It's the involuntary muscle contractions that cause injury. That one gave me heavy bruising and a gash.
Oscilloscopes, more than once. All different models. I wonder if the engineers who designed them chuckled as they configured the focus control near the top right side on some of these. That's about 1.5 KV. Gets your attention, then you have the jitters for a couple hours. Just plain unpleasant.
Fender Twin amplifiers. Yup. They run those poor 6L6GCs hot, about 475 VDC worth of hot. When you're chasing an odd problem, discharging eventually doesn't get done. When you become part of an unintentional circuit, you tend to speak in tongues briefly. It's best not to be in a hurry.
Over the years I've suffered many self inflicted zings and zaps. Left hand in the pocket has been a life saver for me I'm sure. The shock that bothered me the most was the one I received while attending Ryerson in Toronto. My lab partner was staring off into space as I worked at putting a lab together. He came too just long enough to wonder why there was an AC cord lying on the bench. I had my back turned, so I didn't actually see him absent-mindedly plug the damn thing in. That one stung quite a bit. My lab partner had to finish putting the experiment together, but not until he explained to the prof. what had just taken place. Yup, I had the jitters again for a few hours. That lab partner I had 28 years ago or so is still a very good friend. He maintains that he doesn't know why he plugged the cord in.
Car ignition systems? Man, they sting along with the sensation of being whacked with a wooden dowel with every jolt. Not too much fun either.
The old toss the charged up capacitor thing was one of my favorite tricks. Thing is, you have to make sure the cap is a low capacitance value or it really hurts the victim. A school chum charged up an 8 uF, 450 V model to about 400 V. Chucked it at another while calling his name. Guy turns, catches the cap and gets nailed. Well, the discharged capacitor hurt more coming back. The victim not only had a great throwing arm, but he also had excellent control. The "chum" got it in the arm pit (discharged mostly now). He was only wearing a light tee-shirt. The reaction to a shock is normally the most dangerous part of the event at reasonable voltages. It certainly was in this case. 😀
-Chris
In the US, many homes have a water filter on the main line coming into the house. The ground from the main electrical panel may be directly "earthed", or it could be attached to the water line. If the filter input to output isn't jumpered with something like a #0 braided cable the ground can be floating. Caveat elector.
Two that stick in my head: it was one of my birthdays (12th maybe?) where i was plugging in an extension cord and the plug was bent a little so i had to wiggle it into the socket. Well the inevitable happened and my finger slipped onto the live 120v prong and latched onto me for a good few seconds, when i finally ripped myself off of the power. I laid on the ground for a few minutes shaking (scary)
Next incident wasnt nearly as bad but worth mentioning. I was about 17 or so when I was just starting to get into home audio. I had an old Yamaha reciever that I was happy with, but was dying to see how these things operate. So with caution, I pulled to top off and started investigating. After poking around I see a couple of line fuses that look a little off center. Of course what do I forget to do before I center them...pull the plug! Recieved a nice little buzz from that one. Ever since I've been pretty careful and double check all my connections. Knock on wood haven't had any close calls since then. Live and learn I guess, lol
Next incident wasnt nearly as bad but worth mentioning. I was about 17 or so when I was just starting to get into home audio. I had an old Yamaha reciever that I was happy with, but was dying to see how these things operate. So with caution, I pulled to top off and started investigating. After poking around I see a couple of line fuses that look a little off center. Of course what do I forget to do before I center them...pull the plug! Recieved a nice little buzz from that one. Ever since I've been pretty careful and double check all my connections. Knock on wood haven't had any close calls since then. Live and learn I guess, lol
My weirdest incident involves a PC. I don't understand what happened really but it was my nastiest encounter with electricity. I was fiddling with my computer (with its case open) while it was operating and stuck my fingers somewhere inbetween two bus slots for some reason I can't quite remember now (but I'm sure it was very smart thing to do at that time). Loud pop and some visible arcing later I pulled my hand out and there as a clear puncture on my finger with blood dripping out. Computer just kept working as if nothing had happened. After turning it off (nothing like one's own experience to learn from !) and taking it apart I noticed there was an irregularly-shaped area of the board (PCB) that had rainbow pattern resembling an oil spill you see on tarmac on wet days. It was visible through the green board lacquer.
My guess is I somehow managed to discharge all the low voltage PSU caps but I can't understand how low voltage supply could pass enough current through my body to break the skin open ???
Other than that it's pretty mundane, just the regular "touching the 230V AC with bare hand" on multiple occassions and "getting zapped by the PSU multiple times in a row while trying to pull out a tube from its socket with left hand holding the board" kind of stupidity.
My guess is I somehow managed to discharge all the low voltage PSU caps but I can't understand how low voltage supply could pass enough current through my body to break the skin open ???
Other than that it's pretty mundane, just the regular "touching the 230V AC with bare hand" on multiple occassions and "getting zapped by the PSU multiple times in a row while trying to pull out a tube from its socket with left hand holding the board" kind of stupidity.
I used the outside of an old Tek CRT as a hand rest while leaning over to see someone's bench. Replace covers.
My earth ground in my home carries a small charge. I can't track down why! But if I'm in my basement w/out shoes, plug in a computer case, even if the power strip is turned off, touch the case and I get a mild shock! (or anything w/ a case that's earth grounded). Neutral is neutral.. I could touch it w/ my tongue standing on a wet floor w/ bare feet and not get shocked.. but earth ground.... BZZZ (It's def. 60hz, but not much current. It doesn't hurt, but u can certainly feel it...)
Ohh,I once had the "toss a cap at a buddy" backfire on me.. My buddy was wise to electronics,and knew anything in my 'mad lab' was potentially dangerous.I went to toss it at him,and just before it left my hand,I got a major belt,he saw the cap coming at him,and jumped out of the way...I thought it was discharged.Serves me right,I guess.
The same buddy was once playing with my Jacobs ladder,and didn't realize that black automotive heater-hose was slightly conductive..just as I said "don't do that!" he tapped one of the electrodes,and quickly realized what made the hose that black color -carbon.
Another time at the gf's house,her DSL/phone line was being sporadic,so I went outside with my handy Leatherman tool (uninsulated) popped the service box open,and started tightening the connections down...while wearing socks,on wet concrete.. wouldn't ya know it,someone called the instant I grabbed the nut (just my luck!),and I felt the phone ringing in my head. Not fun! -Really,I should have known better,wet concrete and no shoes,just dumb,even if it was "only" 48V or so. (the ring signal is closer to 100V)
When I was a kid my parents would always ask me to plug things in behind the table,couch,etc. since I was small enough to get back there.. I'd always grab the plug by the prongs,so I could 'feel it' into the socket.. Ohh,I "felt it" alright.. I'd do it almost every time too.. "It's just 120" said the 6 year old. Sheesh. I must have been shocked by the mains in that manner at least 50 times as a kid.
The same buddy was once playing with my Jacobs ladder,and didn't realize that black automotive heater-hose was slightly conductive..just as I said "don't do that!" he tapped one of the electrodes,and quickly realized what made the hose that black color -carbon.
Another time at the gf's house,her DSL/phone line was being sporadic,so I went outside with my handy Leatherman tool (uninsulated) popped the service box open,and started tightening the connections down...while wearing socks,on wet concrete.. wouldn't ya know it,someone called the instant I grabbed the nut (just my luck!),and I felt the phone ringing in my head. Not fun! -Really,I should have known better,wet concrete and no shoes,just dumb,even if it was "only" 48V or so. (the ring signal is closer to 100V)
When I was a kid my parents would always ask me to plug things in behind the table,couch,etc. since I was small enough to get back there.. I'd always grab the plug by the prongs,so I could 'feel it' into the socket.. Ohh,I "felt it" alright.. I'd do it almost every time too.. "It's just 120" said the 6 year old. Sheesh. I must have been shocked by the mains in that manner at least 50 times as a kid.
I would think real hard and fast about getting an electrician in to have a look at what is going on. Normally neutral and safety ground are tied together in the main panel.. If you take the cover off you should see a grounding bar attached to the case of the panel with a bunch of neutral (white) and bare copper (or sometimes green insulated) wires all going to the ground bar.
If your house was built was built prior to the early 1960s you may not have actual outlet grounds despite having a 240V single phase 3 wire system.
You should definitely track this down. Switch off circuit breakers one by one when no appliance is working (!) and see whether it goes away. If it does, the culprit is obviously supplied from the offending chain after that particular breaker (faulty line filter capacitor in dishwasher or something like that ?). Track it down further by unplugging things one by one.
If the problem doesn't go away even though you have removed/switched off ALL the breakers in your house, it is obviously an outside problem and you should get somebody to fix it for you.
Either way, you can't have that going on forever, it is potential threat (what if somebody using a pacemaker gets shocked ?).
I've had one out.. said there's nothing out of the ordinary!
and I have one of the basic outlet testers u can get at the hardware store, and those all show my outlets testing OK. (which is also the only thing I saw the electrician do to test.. tho he did poke around in the box for a while) Both definitely go to ground.
One ground wire goes into the ground right outside where the electric meter is. The other ground wire goes to my water pipes. It's been a couple of years since I looked at it (when I moved in) and I forget which is which. I thought the neutral went to the wire outside, and earth went to my water pipes.. I'll need to check it out again, I guess.
I know all the other houses Ive lived in did have the grounds tied together at the box, but this one doesn't.
My water pipes are connected all the way out my basement wall.. no filter, as someone earlier in this thread mentioned.
well anyway.. you're right.. I should try looking into that some more because it's not right!
and I have one of the basic outlet testers u can get at the hardware store, and those all show my outlets testing OK. (which is also the only thing I saw the electrician do to test.. tho he did poke around in the box for a while) Both definitely go to ground.
One ground wire goes into the ground right outside where the electric meter is. The other ground wire goes to my water pipes. It's been a couple of years since I looked at it (when I moved in) and I forget which is which. I thought the neutral went to the wire outside, and earth went to my water pipes.. I'll need to check it out again, I guess.
I know all the other houses Ive lived in did have the grounds tied together at the box, but this one doesn't.
My water pipes are connected all the way out my basement wall.. no filter, as someone earlier in this thread mentioned.
well anyway.. you're right.. I should try looking into that some more because it's not right!
Older homes often earthed the box to the plumbing system. If you've had your plumbing worked on or your water meter changed, make sure there is still an electrical path to the main water line coming out of the ground (jumper around the meter, etc).
My house had ground issues when we moved in (built in 1947). I replaced the entire breaker box due to overloaded rails, fixed the missing plumbing jumper and also added an 8ft grounding rod to the outside near the box. The grounding rod is the way to go. It should be at least 8 ft long.
As far as the outlets, even my old house is OK. It's all wired with BX. Ideally, even if your ground is floating, nothing should be sinking current to it. Do you have any really old radios or appliances? Sometimes they strapped ceramic caps across the mains to filter EMI and they always become leaky. Could also be failing insulation in a motor somewhere. Definitely get that fixed!!!
I thought you were on to something. I have an ancient refrigerator in my basement, but that wasn't it. Unplugged my other big appliances and new fridge, and furnace, and bunch of other stuff, and still feel it.
I don't really even notice it on my hands, but if my arm touches the metal case, I feel it. I take back my comment that it's definitely 60hz. It feels more like the sharp sting you get from a low powered tesla coil. (but not nearly that strong)
Well, when I have time this weekend, I'll go through and shut off all the breakers, turn one on at a time and try to get to the bottom of it.
A new grounding rod is something I've thought of as well. I really like that idea. Just take the old stuff out of the equation.
I don't really even notice it on my hands, but if my arm touches the metal case, I feel it. I take back my comment that it's definitely 60hz. It feels more like the sharp sting you get from a low powered tesla coil. (but not nearly that strong)
Well, when I have time this weekend, I'll go through and shut off all the breakers, turn one on at a time and try to get to the bottom of it.
A new grounding rod is something I've thought of as well. I really like that idea. Just take the old stuff out of the equation.
Sounds like your arm is discharging whatever it is that is trying to sink to it. That also implies that your ground is floating, at least on the leg you are doing this test on. Ever put a meter between ground and neutral? Try it at this location, other locations, and at the box.
How old is your home? Are you using any X10 devices or any other home automation system?
How old is your home? Are you using any X10 devices or any other home automation system?
Grab a meter, pour a teaspoon of water on the concrete and put one lead to that and the other to the offending applliance. I bet you have at least 40 volts and maybe more.
When I worked for TI in the 80s we were designing the TI520/530 Industrial controls which used TIWAY for communications between the local and remote bases. We had two 19" racks with 4' X 6' aluminum panels mounted on them with the equiptment on the panels. One day Charlie (Engineer) was leaning on one panel and put his hand on the other. He let out a yell and withdrew his hand rapidly. Seems both panels were plugged into two different circuits through 3 prong power strips. Faulty ground in one allowed a 60V potential between the two panels.
When I worked for TI in the 80s we were designing the TI520/530 Industrial controls which used TIWAY for communications between the local and remote bases. We had two 19" racks with 4' X 6' aluminum panels mounted on them with the equiptment on the panels. One day Charlie (Engineer) was leaning on one panel and put his hand on the other. He let out a yell and withdrew his hand rapidly. Seems both panels were plugged into two different circuits through 3 prong power strips. Faulty ground in one allowed a 60V potential between the two panels.
Home was built in the mid 50's It didn't have 3 prong outlets originally, but the previous owner had a good portion of the wiring redone. Had a new breaker box put in.
The water company put a new water meter out in my yard last spring, which could have made things worse, but this problem was definitely there before hand.
I just measured between earth on an outlet and the wet concrete floor, and measured 7 volts ac, 0 dc (I wouldn't trust the reading from my meter, but there's definitely power there.. I didn't think my meter could read AC that low, though). Earth to neutral is 0.
So, scratch my earlier comment that neutral and earth were different, because neutral to wet concrete is also 7v. Maybe the electrician tied them together when he was out..
The water company put a new water meter out in my yard last spring, which could have made things worse, but this problem was definitely there before hand.
I just measured between earth on an outlet and the wet concrete floor, and measured 7 volts ac, 0 dc (I wouldn't trust the reading from my meter, but there's definitely power there.. I didn't think my meter could read AC that low, though). Earth to neutral is 0.
So, scratch my earlier comment that neutral and earth were different, because neutral to wet concrete is also 7v. Maybe the electrician tied them together when he was out..
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