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High voltage safety precautions
Hi,
I'm going to do some experimentation on high voltage equipments ( transformers, power supplies, capacitor banks, lasers , etc.. ). Does anyone know where I could find some safety guidelines or notes about working with this dangerous stuff ? ( I wouldn't like to die because of a spark jump and make my wife a widow... ) Thanks Stef |
High voltage safety precautions
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High voltage safety precautions
On Mon, 04 May 2009 13:04:40 -0400, Phil Hobbs
wrote: wrote: Hi, I'm going to do some experimentation on high voltage equipments ( transformers, power supplies, capacitor banks, lasers , etc.. ). Does anyone know where I could find some safety guidelines or notes about working with this dangerous stuff ? ( I wouldn't like to die because of a spark jump and make my wife a widow... ) Thanks Stef Oh, brother. Do her a favour and take up welding instead. Cheers Phil Hobbs Wonder what his wife's take on this experiment is? Maybe she's all for it? g |
High voltage safety precautions
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High voltage safety precautions
On May 4, 5:59*pm, "Charles" wrote:
http://video.google.com/videoplay?do...01008541895226 Two deathly dangers - one from actual electrical shock, one from impaling yourself on something sharp when you jump from the shock and bleed to death |
High voltage safety precautions
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High voltage safety precautions [OT]
Bob Larter wrote:
hr(bob) wrote: On May 4, 5:59 pm, "Charles" wrote: http://video.google.com/videoplay?do...01008541895226 Two deathly dangers - one from actual electrical shock, one from impaling yourself on something sharp when you jump from the shock and bleed to death Heh. The second point is the one that tends to catch telco tech's when the phone rings while they're working on the MDF. ;^) If the 'phone rings while you are doing the ironing, you can get a badly burned ear. -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk |
High voltage safety precautions
Two deathly dangers - one from actual electrical shock, one from impaling yourself on something sharp when you jump from the shock and bleed to death A good reason to find another line of work. Just remember, a live circuit looks exactly like a dead circuit. Also HV caps can hold a charge enough to bang you too. If you learned on tube gear, then maybe you know enough, but LV circuits just don't have the urgency required to heighten your paranoia for survivability. You essentially have to develop a checklist in your head for each time you put a hand (only one) into the dead equipment and never fail. Instructions are normally in the Service Manual of all HV equipment. |
High voltage safety precautions
JB wrote:
Two deathly dangers - one from actual electrical shock, one from impaling yourself on something sharp when you jump from the shock and bleed to death My classic screwup was a time, as a smartarse teenager, when I was working on a 28" display monitor, & /thought/ I'd discharged the CRT correctly via the ultor cap. I lifted the ultor cap to unhook it, & a giant spark bit me. The shock threw me clear across the room, & I just missed slamming into a bench. A good reason to find another line of work. Just remember, a live circuit looks exactly like a dead circuit. Also HV caps can hold a charge enough to bang you too. If you learned on tube gear, then maybe you know enough, but LV circuits just don't have the urgency required to heighten your paranoia for survivability. You essentially have to develop a checklist in your head for each time you put a hand (only one) into the dead equipment and never fail. Instructions are normally in the Service Manual of all HV equipment. All good advice. -- W . | ,. w , "Some people are alive only because \|/ \|/ it is illegal to kill them." Perna condita delenda est ---^----^--------------------------------------------------------------- |
High voltage safety precautions
Bob Larter wrote: My classic screwup was a time, as a smartarse teenager, when I was working on a 28" display monitor, & /thought/ I'd discharged the CRT correctly via the ultor cap. I lifted the ultor cap to unhook it, & a giant spark bit me. The shock threw me clear across the room, & I just missed slamming into a bench. This explains a lot! ;-) -- You can't have a sense of humor, if you have no sense! |
High voltage safety precautions
Michael A. Terrell wrote:
Bob Larter wrote: My classic screwup was a time, as a smartarse teenager, when I was working on a 28" display monitor, & /thought/ I'd discharged the CRT correctly via the ultor cap. I lifted the ultor cap to unhook it, & a giant spark bit me. The shock threw me clear across the room, & I just missed slamming into a bench. This explains a lot! ;-) I suppose you've never zapped yourself? ;^) -- W . | ,. w , "Some people are alive only because \|/ \|/ it is illegal to kill them." Perna condita delenda est ---^----^--------------------------------------------------------------- |
High voltage safety precautions
Bob Larter wrote: Michael A. Terrell wrote: Bob Larter wrote: My classic screwup was a time, as a smartarse teenager, when I was working on a 28" display monitor, & /thought/ I'd discharged the CRT correctly via the ultor cap. I lifted the ultor cap to unhook it, & a giant spark bit me. The shock threw me clear across the room, & I just missed slamming into a bench. This explains a lot! ;-) I suppose you've never zapped yourself? ;^) Not like that. The HV I worked with wasn't measured in micro amps. It was inside the TV transmitter. One touch, and you're dead. Think what a HV DC power supply for three 65 KW Klystrons would do to you, when the power supply put out a continuous 195 KW. In fact, you wouldn't even need to touch it. -- You can't have a sense of humor, if you have no sense! |
High voltage safety precautions
"Michael A. Terrell" wrote in message
... Bob Larter wrote: Michael A. Terrell wrote: Bob Larter wrote: My classic screwup was a time, as a smartarse teenager, when I was working on a 28" display monitor, & /thought/ I'd discharged the CRT correctly via the ultor cap. I lifted the ultor cap to unhook it, & a giant spark bit me. The shock threw me clear across the room, & I just missed slamming into a bench. This explains a lot! ;-) I suppose you've never zapped yourself? ;^) Not like that. The HV I worked with wasn't measured in micro amps. It was inside the TV transmitter. One touch, and you're dead. Think what a HV DC power supply for three 65 KW Klystrons would do to you, when the power supply put out a continuous 195 KW. In fact, you wouldn't even need to touch it. -- You can't have a sense of humor, if you have no sense! Scares the crap out of me just thinking about it! I've only ever worked consumer electronics, never had any training on high voltage / high frequency power circuits. I once got shocked by a GE 35" tv by only getting near the anode wire. The wire had cracks in it, and I didn't know until it was too late. Felt like it took my arm off! More than once grazed some skin across 120 volts AC whilst working on equipment; never got much more than a "Huh? What was that? Oh, crap. Gotta be more careful..." Mark Z. |
High voltage safety precautions
On Fri, 8 May 2009 06:04:06 -0500, "Mark Zacharias"
wrote: More than once grazed some skin across 120 volts AC whilst working on equipment; never got much more than a "Huh? What was that? Oh, crap. Gotta be more careful..." Mark Z. Funny thing is that 120 volts AC is actually more likely to kill you than 240 volts! |
High voltage safety precautions
Mark Zacharias wrote: Michael A. Terrell wrote: Not like that. The HV I worked with wasn't measured in micro amps. It was inside the TV transmitter. One touch, and you're dead. Think what a HV DC power supply for three 65 KW Klystrons would do to you, when the power supply put out a continuous 195 KW. In fact, you wouldn't even need to touch it. Scares the crap out of me just thinking about it! I've only ever worked consumer electronics, never had any training on high voltage / high frequency power circuits. I once got shocked by a GE 35" tv by only getting near the anode wire. The wire had cracks in it, and I didn't know until it was too late. Felt like it took my arm off! More than once grazed some skin across 120 volts AC whilst working on equipment; never got much more than a "Huh? What was that? Oh, crap. Gotta be more careful..." That is why there are so many safety interlocks in big transmitters. I was moving a RCA TTU-25B transmitter about 15 years ago, and found a small screwdriver jammed in one of the interlock switches. Luckily, the highest voltage in that cabinet was around 350 volts DC, but several of the other cabinets had 7000 VDC for the two water cooled power tetrodes. The transmitter was in nine, four foot square aluminum cabinets that were about seven feet tall. There were two, two foot wide sections that held the special rubber pipe that isolated the HV from ground. That made the entire transmitter 4 feet deep, 40 feet wide and seven feet tall. -- You can't have a sense of humor, if you have no sense! |
High voltage safety precautions
"PeterD" wrote in message ... On Fri, 8 May 2009 06:04:06 -0500, "Mark Zacharias" wrote: More than once grazed some skin across 120 volts AC whilst working on equipment; never got much more than a "Huh? What was that? Oh, crap. Gotta be more careful..." Mark Z. Funny thing is that 120 volts AC is actually more likely to kill you than 240 volts! Only because you may be exposed to it a lot more often. Consider that at 240v you will be dissipating 4 times the power through your bod! |
High voltage safety precautions
On Fri, 8 May 2009 06:04:06 -0500, "Mark Zacharias"
wrote: "Michael A. Terrell" wrote in message ... Bob Larter wrote: Michael A. Terrell wrote: Bob Larter wrote: My classic screwup was a time, as a smartarse teenager, when I was working on a 28" display monitor, & /thought/ I'd discharged the CRT correctly via the ultor cap. I lifted the ultor cap to unhook it, & a giant spark bit me. The shock threw me clear across the room, & I just missed slamming into a bench. This explains a lot! ;-) I suppose you've never zapped yourself? ;^) Not like that. The HV I worked with wasn't measured in micro amps. It was inside the TV transmitter. One touch, and you're dead. Think what a HV DC power supply for three 65 KW Klystrons would do to you, when the power supply put out a continuous 195 KW. In fact, you wouldn't even need to touch it. -- You can't have a sense of humor, if you have no sense! Scares the crap out of me just thinking about it! I've only ever worked consumer electronics, never had any training on high voltage / high frequency power circuits. I once got shocked by a GE 35" tv by only getting near the anode wire. The wire had cracks in it, and I didn't know until it was too late. Felt like it took my arm off! More than once grazed some skin across 120 volts AC whilst working on equipment; never got much more than a "Huh? What was that? Oh, crap. Gotta be more careful..." Mark Z. Oh, you should try working the CO frame in Palm Desert! Temperature is about 90, even with the HVAC running full out, and you put your arm across a set of pins just as ring voltage comes through. ZAP! your arm jerks up... OUCH! as you impale your arm on the pins above ZAP! as your arm comes back down on the pins below just as another ring hits... OUCH!!!! as you impale your arm on the pins above again! Usually, after about two hits you get control... ;-) Charlie |
High voltage safety precautions
On May 7, 8:56*am, Bob Larter wrote:
My classic screwup was a time, as a smartarse teenager, when I was working on a 28" display monitor, & /thought/ I'd discharged the CRT correctly via the ultor cap. I lifted the ultor cap to unhook it, & a giant spark bit me. The shock threw me clear across the room, & I just missed slamming into a bench. Mine was moving the meter probe tips slightly while looking over at the meter. Diodes explode into many fast moving pieces, and melt your probe tips. Wear a full face shield, not just goggles, and a heavy duty full sleeve lab coat. Remove watches, rings, necklaces, etc. If you don't want a spark to hit it, don't put metal on it. |
High voltage safety precautions
On 5/8/2009 3:06 PM Charlie E. spake thus:
Oh, you should try working the CO frame in Palm Desert! Temperature is about 90, even with the HVAC running full out, and you put your arm across a set of pins just as ring voltage comes through. ZAP! your arm jerks up... OUCH! as you impale your arm on the pins above ZAP! as your arm comes back down on the pins below just as another ring hits... OUCH!!!! as you impale your arm on the pins above again! Usually, after about two hits you get control... ;-) Hah! That reminds me of that ditty about the Irishman hoisting bricks up with a pulley ... .... ah, there it is: Why Paddy's Not At Work Today (Tune: "In The Garden Where The Praties Grow") Dear Sir, I write this note to you to tell you of my plight For at the time of writing I am not a pretty sight My body is all black and blue, my face a deathly grey And I write this note to say why Paddy's not at work today. Whilst working on the 14th floor some bricks I had to clear To throw them down from such a height was not a good idear The foreman wasn't very pleased, the bloody awkward sod And he said I'd have to cart them down the ladders in me hod. Now clearing all these bricks by hand, it was so very slow So I hoisted up a barrel and secured the rope below But in my haste to do the job I was too blind to see that a barrel full of building bricks was heavier than me! And so when I untied the rope, the barrel fell like lead And, clinging tightly to the rope, I started up instead I shot up like a rocket til to my dismay I found That halfway up I met the bloody barrel coming down! The barrel broke my shoulder, as toward the ground it sped And when I reached the top, I banged the pulley with my head I hung on tightly, numb with shock, from this almighty blow And the barrel spilled out half the bricks, 14 floors below. Now when these bricks had fallen from the barrel to the floor I then outweighed the barrel, and so started down once more Still clinging tightly to the rope, my body racked with pain When, halfway down, I met the bloody barrel once again! The force of this collision, halfway up the office block caused multiple abrasions and a nasty state of shock Still clinging tightly to the rope, I fell towards the ground And landed on the broken bricks the barrel scattered round! I lay there, groaning, on the ground; I thought I'd passed the worst But the barrel hit the pulley wheel, and then the bottom burst... A shower of bricks rained down on me; I hadn't got a hope... As I lay there bleeding on the ground, I let go the bloody rope! The barrel it was free to fall, and down it came once more And landed right across me, as I lay upon the floor It broke three ribs and my left arm, and I can only say: That I hope you understand why Paddy's not at work today! -- Save the Planet Kill Yourself - motto of the Church of Euthanasia (http://www.churchofeuthanasia.org/) |
High voltage safety precautions
"JB" wrote in news:C31Nl.69$5F2.54
@nwrddc01.gnilink.net: "PeterD" wrote in message ... On Fri, 8 May 2009 06:04:06 -0500, "Mark Zacharias" wrote: More than once grazed some skin across 120 volts AC whilst working on equipment; never got much more than a "Huh? What was that? Oh, crap. Gotta be more careful..." Mark Z. Funny thing is that 120 volts AC is actually more likely to kill you than 240 volts! Only because you may be exposed to it a lot more often. No! Because 240 is more likely to 'throw you off' and 120 is more likely to 'freeze you on'. 15 micro amps across the heart kills. 60 Hz is especially bad for causing V-fib. Without a defibrillator, or CPR you are dead in 6 minutes. 15 milli amps is sufficient to 'freeze your muscles' so you can't let go. You start with relatively dry skin and get a good grip onto a hot item. You can't let go. Skin at the points of contact blisters. resistance goes down. current goes up. you cook. Higher voltages produce very violent muscle contractions and can (if you are lucky) throw you clear of the circuit. Consider that at 240v you will be dissipating 4 times the power through your bod! -- bz 73 de N5BZ k please pardon my infinite ignorance, the set-of-things-I-do-not-know is an infinite set. remove ch100-5 to avoid spam trap |
High voltage safety precautions
On May 6, 7:36 am, 1PW wrote:
On 05/04/2009 04:52 AM, sent: Hi, I'm going to do some experimentation on high voltage equipments ( transformers, power supplies, capacitor banks, lasers , etc.. ). Does anyone know where I could find some safety guidelines or notes about working with this dangerous stuff ? ( I wouldn't like to die because of a spark jump and make my wife a widow... ) Thanks Stef Hello Stef: Please define the levels of high voltage you are referring to. Laser safety is also an entirely different subject. What type & class laser? Pete -- 1PW @?6A62?FEH9:DE=6o2@=]4@ [r4o7t] I refer to voltages found for example in CO2 lasers and CRT chassis. I found a nice page with guidlines: http://www.repairfaq.org/sam/safety.htm Is there a rule for how long a spark can jump, given the voltage and the dielectric ( tipically air at certain humidity) ? Furthermore, why should I keep a hand in my poket while around HV ? |
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