I remember the house where I lived for the first ten years of my life. There was only ONE three-pin 15A socket, and that was an addition, in the kitchen. All other downstairs sockets were two-pin 15A and 2-pin 5A upstairs, the latter fed from the lighting circuit. BTW, all circuits were fused in both line and neutral (ceramic fuse carriers with fuse wire), and RCDs were still some time in the future!
Electric shock...from being stupid. :/
- Thread starter eveares
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Very familiar - the house in which I spent the my early teenage years was almost exactly the same as that - and was not re-wired until the late 70s, or maybe even early 80s.
Kind Regards, John
Yes I did, from an faulty immersion heater which I forget to turn off after testing. Wow, what a jolt! Idiot! Should not be a plumber job.....
Daniel
I have had quite a few shocks in my time.
Attempted to change the speaker fuses on an amplifier with it turned off but still plugged in and got a shock when I brused my arm against the mains input connections.
Got a shock by absent mindedly putting a figure eight lead in my mouth while the other end was plugged in.
got a shock off a homemade inverter for small flourescent tubes (ELV input, but open circuit output range just puthing into the HV band*) by touching one wire of the (floating output) and the end of the tube (to which i'd just hooked up the other wire)
Had a few other shocks off the mains of which I don't remember the details.
most recently got a shock off an unplugged power supply. The thing was SUPPOSED to have drain resistors on the primary capacitors but one of them was open-circuit.
* IIRC the version I got the shock off was about 700V AC at fairly high frequency. We later added a rectifier/capacitor circuit and managed to get a multimeter to give an off-scale indication on the 1000V DC range.
Attempted to change the speaker fuses on an amplifier with it turned off but still plugged in and got a shock when I brused my arm against the mains input connections.
Got a shock by absent mindedly putting a figure eight lead in my mouth while the other end was plugged in.
got a shock off a homemade inverter for small flourescent tubes (ELV input, but open circuit output range just puthing into the HV band*) by touching one wire of the (floating output) and the end of the tube (to which i'd just hooked up the other wire)
Had a few other shocks off the mains of which I don't remember the details.
most recently got a shock off an unplugged power supply. The thing was SUPPOSED to have drain resistors on the primary capacitors but one of them was open-circuit.
* IIRC the version I got the shock off was about 700V AC at fairly high frequency. We later added a rectifier/capacitor circuit and managed to get a multimeter to give an off-scale indication on the 1000V DC range.
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Does sitting on the metal cased 12V accumulators powering a Wireless Set No.19 whilst tinkering inside the linear amp with the transmit key pressed (to try to get more power by tweaking the bias etc.) count as mundane? Threw me right across the room. Oh the foolish things we do when we are young.
Yes, most of us have tales of youthful foolishness which we could tell! Mind you, 'back then' many of the hazards were presented to us on a plate, as 'accidents waiting to happen'.....
If we're talking about aged military equipment, do you recall the R107 receiver? Many models had an exposed socket (male, with large exposed pins) on the front panel which, when it was used in conjunction with the WS12 transmitter, enabled the transmitter to operate a relay in the R107 to mute it during transmission. However, one of those large exposed pins was at 0V and the other at HT voltage (about 250V, IIRC). The nearest to 'protection' was a red written warning on the panel (visible, but not readable, on pic below). In my mis-spent youth, I inadvertently touched those two pins on many an occasion when using the receiver 'standalone' (i.e. with no plug in that socket)!
Kind Regards, John
IIRC different standards vary on that. Some consider anything above low voltage to be high voltage, others have a "medium voltage band"
Ok the thresholds were higher than I remembered.
Indeed so. BAS is quoting some different definitions, but, for example, BS7671 does not recognise 'Medium Voltage' - it defines High Voltage as "Normally exceeding low voltage"!
You're conceding too easily
As far as BS7671 is concerned, 700V AC between a conductor and earth is high voltageKind Regards, John
Oh no it isn't!You're conceding too easily
See the definition in Part 2 for "Voltage, nominal".
Eh? That's what I was quoting:Oh no it isn't!You're conceding too easily
Are we reading the same book?Part 2 of BS7671 said:
Kind Regards, John
Whoops!Eh? That's what I was quoting:Oh no it isn't!You're conceding too easily
Are we reading the same book?Part 2 of BS7671 said:
Kind Regards, John
I'd missed the "between conductors and Earth" bit of your post.I thought you might have doneWhoops!
My comment was 'in context', since it seems very likely that the ('high frequency') 700V a.c. to which plugwash referred will have been 700V relative to Earth, and not the pd between two phases of a multi-phase supply!Kind Regards, John
Plug encountered 700V at the output of an inverter, which as it had an ELV input was surely not referenced to earth.
But as for definitions, it looks as though the IEC don't officially use any L/M/H labels.
http://www.electricalengineering-book.com/voltagesystems.html
http://cmapspublic2.ihmc.us/rid=1L6G6428L-XZ32Y6-1H9G/iec60038.pdf
http://myelectrical.com/notes/entryid/11/voltage-level-confusion
As I said in my post it was a floating output* so you could touch it without getting a shock as long as you didn't touch both ends at once, my mistake was not realising that before the connection was established the terminals on the lamp I was connecting to were effectively the other end of the supply.
Not sure how you would count that, do you assume that it's centered with respect to earth? do you assume that one end is likely to get inadvertandly tied to earth putting the other end at 700V relative to earth?. I guess it's a situation the authors of BS7671 didn't really consider.
Also no idea how accurate the cheap multimeter was with the frequency and waveform in question.
* coming from a small transformer that was being used in a way decidedly outside it's specifications. IIRC the transformer was intended to be used to convert 240V to 3V at 50Hz but we were using what was intended to be the secondary as the primary. We were driving it off some electronics powered from a 12V DC supply, I don't recall exactly what the frequency was but iirc it was substantially higher than mains frequency.
Not sure how you would count that, do you assume that it's centered with respect to earth? do you assume that one end is likely to get inadvertandly tied to earth putting the other end at 700V relative to earth?. I guess it's a situation the authors of BS7671 didn't really consider.
Also no idea how accurate the cheap multimeter was with the frequency and waveform in question.
* coming from a small transformer that was being used in a way decidedly outside it's specifications. IIRC the transformer was intended to be used to convert 240V to 3V at 50Hz but we were using what was intended to be the secondary as the primary. We were driving it off some electronics powered from a 12V DC supply, I don't recall exactly what the frequency was but iirc it was substantially higher than mains frequency.
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