I want to live.
In the interest of safety, I would like to collect whatever safety tips and practices this forum kindly and experienced members will share, so that all may benefit.
First, some warnings and disclaimers:
- Any voltage can be deadly.
- Amplifiers are dangerous--each person (me included) is responsible for deciding if they are willing to risk their life, and for ensuring that whatever information they receive is correct
- This forum and its members accept no responsibility for any death, injury or property damage that result from any of these suggestions--your safety is your own responsibility.
And please note that I have *no* amplifier hardware on hand, and will not for a while. This is a discussion only, and I will only be talking about doing stupid things, not actually doing them.
Okay, with that out of the way, I would like any tube equipment electrical safety advice you care to share, both in general, and for what I will classify (for the purposes of this discussion) as UltraHighVoltage--1000V to 1500V.
I'll start with what I think I know, and you can add more or correct me if I am wrong.
I can think of two basic rules of thumb--
- Make sure any charge-storing devices remain discharged while working on the equipment
- Avoid creating a circuit which would pass current through the heart.
From those rules of thumb, I can think of these specific practices:
- Put a drain load across all significant charge-storage devices (e.g. B+), and leave them there for the duration of your work--some devices can redevelop voltage if left unloaded.
- Verify that all charge-storing devices are discharged before starting work.
- Always work with only one hand--keep the other hand in your pocket.
- Use hook probe for secure connections and to avoid shorts.
- Wear rubber gloves and rubber soled shoes--no bare feet or socks.
- Make sure your design has the chassis safety grounded--connected to the ground wire of the power plug.
Okay, what do you think about these practices, and what can you add?
One member spoke of a "bench isolating transformer". What is that, what does it do, and how is it installed/used?
Also, what extra design and usage practices apply to UltraHighVoltage (1000V to 1500V) electronics? I'm thinking about things like component choices, test procedures (standard DMMs are only rated to 600V), design practices (danger of arcing), etc.
Thanks for your attention and advice. Although I hope for courtesy, I'd rather be flamed figuratively than literally.
Best,
George Ferguson
A neccessary post.
I can add;
If your mind is busy with something else, for example a problem with your wife/GF, do not work on high voltage.
I did talk about the isolating transformer. It is normally used when a person must work on equipment that have or may have a live chassis like older television sets AC/DC radio's et al The Television sets did have a warning inside the cabinet to this effect . The purpose is that if the chassis is handled none of the power wires would give a lethal shock. The mains and power that get used are only galvanically coupled and no direct flow. The input is the same as the output depending where you are 250 volts in 250 volts out BUT any of the connections to the equipment can be touched and no shock experienced if all goes well the DC insulation is the same as with any low voltage transformer I.E. 2000 volts. I hope this helps
The most important is to be CAREFUL and think twice before you put your hands inside the equipment.
Lately I have build a tube amplifier with 2 transmitting tubes operating at 5000V.
I have installed warning signs on my bench and on the equipment ..
" Warning! Hazardous area ! Do not touch ! 5000V are present ! Death is permanent! "
This might be helpful to remind you the dangers which included while working on high voltage equipment !
Lately I have build a tube amplifier with 2 transmitting tubes operating at 5000V.
I have installed warning signs on my bench and on the equipment ..
" Warning! Hazardous area ! Do not touch ! 5000V are present ! Death is permanent! "
This might be helpful to remind you the dangers which included while working on high voltage equipment !
I completely agree with you on that an isolation transformer is a must to live longer.
This is NOT true. You can certainly be harmed even with a floating circuit having perfect isolation, by touching parts of the circuit with both hands simultaneously.
Yes - you can touch any one point in the circuit, like the birds who sit on HV transmission lines! The benefit being that if you're connected to the building earth in some way and the chassis happens to be connected to the equipment live, using an isolating transformer means you won't get a belt.
Another suggestion (not always practical, but certainly essential if you're in any doubt as to the circuit): if you expect >50V DC, have a buddy with you while you work, with an insulated hook to pull you away from the equipment in case of shock.
Another suggestion (not always practical, but certainly essential if you're in any doubt as to the circuit): if you expect >50V DC, have a buddy with you while you work, with an insulated hook to pull you away from the equipment in case of shock.
NEVER touch live circuitry, or even dead circuitry that you have not proven to be dead. It's extremely irresponsible to suggest otherwise.
We would ban anyone doing this from our lab.
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Er, that's not what I meant. Of course you should never deliberately touch any live circuitry. However if you accidentally touch one point in the circuit and have no connection to a different point in the circuit you will not get a shock. Therefore the isolating transformer protects against accidents (or faulty wiring). Apologies if you misunderstood my intent.
Even if this were safe (and it isn't), most people instinctively use both hands.
This can easily be fatal. NEVER work on a live circuit. Only work on a safe,
discharged circuit. Attach probes, and only then power up for measurements.
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I think,
Its fair to say that an isolation transformer is a must on equipment, to then make an assumption you are safe is not a good idea!
You should never work on live equipment, testing is not working!
As soon as you pick up a tool to do work you are working. Live means charged with a potential (that includes charged capacitors when switched off).
An isolation transformer is only another measure for safer working.
To say you can touch a live cable because you are "isolated from Earth" is misleading. A potential between any part of the body will/can cause a shock! that includes holding earthed appliances like a soldering iron.
Never forget that solder is conductive and if you are holding it and try to solder a live circuit you could have a fatal shock!
The point is if it can happen it will happen! Most engineers experience a shock during their working lives the trick is to survive it! And they know what they are doing!
Never assume anything such as "its off" its off is one thing its dead is another!
Regards
M. Gregg
Its fair to say that an isolation transformer is a must on equipment, to then make an assumption you are safe is not a good idea!
You should never work on live equipment, testing is not working!
As soon as you pick up a tool to do work you are working. Live means charged with a potential (that includes charged capacitors when switched off).
An isolation transformer is only another measure for safer working.
To say you can touch a live cable because you are "isolated from Earth" is misleading. A potential between any part of the body will/can cause a shock! that includes holding earthed appliances like a soldering iron.
Never forget that solder is conductive and if you are holding it and try to solder a live circuit you could have a fatal shock!
The point is if it can happen it will happen! Most engineers experience a shock during their working lives the trick is to survive it! And they know what they are doing!
Never assume anything such as "its off" its off is one thing its dead is another!
Regards
M. Gregg
Also, all wires have at least two ends, just because you can see one of them does not mean the other is not trying to kill you.....
Bleeder resistors, mechanical interlocks and a 'chicken stick' (Length of broom handle with a metal hook screwed into the end and a permanent ground lead) are all good ideas for working on HV supplies.
Warning lights are also a good plan, I like simple neon relaxation oscilators connected across energy storage caps.
If you use a microswitch as a cover interlock and position it so that removing a screw opens the interlock well before the panel becomes removable this gives a chance for the bleeders to do their work.
Electrical interlocks are often a good idea where the PSU is remote from the load chassis, set them up so that then will open if the amplifier chassis loses its earth connection.
Regards, Dan.
Bleeder resistors, mechanical interlocks and a 'chicken stick' (Length of broom handle with a metal hook screwed into the end and a permanent ground lead) are all good ideas for working on HV supplies.
Warning lights are also a good plan, I like simple neon relaxation oscilators connected across energy storage caps.
If you use a microswitch as a cover interlock and position it so that removing a screw opens the interlock well before the panel becomes removable this gives a chance for the bleeders to do their work.
Electrical interlocks are often a good idea where the PSU is remote from the load chassis, set them up so that then will open if the amplifier chassis loses its earth connection.
Regards, Dan.
I preferred using a test lamp that get tested every time as I did lose an expensive screwdriver that was specially made on 48 volt battery! Somebody that was buried a month before decided that the battery had to be connected and I did not know it!! If you can connect a test lamp I discovered then pranks are curbed!A lamp draw more attention I used since then the cheapest screwdriver to discharge the capacitor on lift trucks
Jeeeezus, 34 Pages to get these things. Moderator really needs to edit this thread if it is really supposed to be safety practices for working with electricity.
1. get an isolation transformer
2. get a variac (or how about an isolated variable AC power supply and kill two birds with.... one volt)
3. get some insulated screwdrivers and tools
4. read some books or info on safety practices with working with electricity
5. do not work on LIVE circuits with both hands, test live circuits with probes etc or one hand, check with a meter or probe if you are in the middle of work to make sure it is dead.
6. if you have never worked with electricity, then do NOT assume anything, get some education
7. If you do not know how to safely discharge capacitors, then you need to learn how to safely do it.
8. Build a few simple things first to get your technique and your bench practices down before deciding to build that 100 watt SE triode amp.
9. Wear eye protection even if you think it is uncool (although pirates with one eye are indeed cooler) and consider safety gloves. Sweaty palms are NOT your friend and you can get gloves that will insulate you very well. But do not make the mistake on relying on equipment for safety. Rely on best practices.
10. Do not lick batteries to see if they have a charge, and do not point your screwdriver at the klystron to see if it is charged.
A good basic complete electronics course.
Basic Electronics 1 - YouTube
1. get an isolation transformer
2. get a variac (or how about an isolated variable AC power supply and kill two birds with.... one volt)
3. get some insulated screwdrivers and tools
4. read some books or info on safety practices with working with electricity
5. do not work on LIVE circuits with both hands, test live circuits with probes etc or one hand, check with a meter or probe if you are in the middle of work to make sure it is dead.
6. if you have never worked with electricity, then do NOT assume anything, get some education
7. If you do not know how to safely discharge capacitors, then you need to learn how to safely do it.
8. Build a few simple things first to get your technique and your bench practices down before deciding to build that 100 watt SE triode amp.
9. Wear eye protection even if you think it is uncool (although pirates with one eye are indeed cooler) and consider safety gloves. Sweaty palms are NOT your friend and you can get gloves that will insulate you very well. But do not make the mistake on relying on equipment for safety. Rely on best practices.
10. Do not lick batteries to see if they have a charge, and do not point your screwdriver at the klystron to see if it is charged.
A good basic complete electronics course.
Basic Electronics 1 - YouTube
I thought this was interesting..
Cheap meters..when protection fails.
https://www.youtube.com/watch?v=lg44zuxGmMg
Regards
M. Gregg
Cheap meters..when protection fails.
https://www.youtube.com/watch?v=lg44zuxGmMg
Regards
M. Gregg
Attachments
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Some more advices from me:
1. REMOVE any possible distractions - messy working places, disturbing lights, noises, colors, kids, wives!! If you feel something can break your concentration the tiniest bit, don't begin working with potentially lethal stuff!
2. Work slowly, never rush, always think first. Your life is your top priority. NEVER make unplanned movements.
3. Plan and organize your work before starting it. At all costs, avoid thinking at the moment with HV on.
4. Never rely fully on insulations. Think of them they can betray you at any moment. Invest in good quality probes.
5. Keep one hand behind your back. Think of it as a tied hand.
6. Use a light bulb power cord to avoid short circuit burned devices.
7. Control your emotions. If something makes you angry or drifts your mind, making you think of something else, turn OFF the HV immediately.
8. Always, always check capacitor charges and drain them, before starting work on a device.
9. Use crocodile clips to make your test connections BEFORE turning on the device.
1. REMOVE any possible distractions - messy working places, disturbing lights, noises, colors, kids, wives!! If you feel something can break your concentration the tiniest bit, don't begin working with potentially lethal stuff!
2. Work slowly, never rush, always think first. Your life is your top priority. NEVER make unplanned movements.
3. Plan and organize your work before starting it. At all costs, avoid thinking at the moment with HV on.
4. Never rely fully on insulations. Think of them they can betray you at any moment. Invest in good quality probes.
5. Keep one hand behind your back. Think of it as a tied hand.
6. Use a light bulb power cord to avoid short circuit burned devices.
7. Control your emotions. If something makes you angry or drifts your mind, making you think of something else, turn OFF the HV immediately.
8. Always, always check capacitor charges and drain them, before starting work on a device.
9. Use crocodile clips to make your test connections BEFORE turning on the device.