Sciencemadness Discussion Board - Medical Laser

Medical Laser

StevenRS - 28-12-2009 at 14:20

I have recently acquired a large medical laser, and, quite honestly, have no idea what to do with it. It is near-infrared, outputs at 755nm, with widely adjustable power levels. It plugs into my 220 30 amp (American, for dryers and such) so its one serious flashlight. It goes all the way up to 75J per centimeter sq in a 10mm spot, for a 50 ms pulse.

I know virtually nothing about lasers, or high voltage, and am at a loss for what to do with this thing. I got it almost for free, couldn't pass up the opportunity. If you need any more information about it, just ask. I will find a chance to post a link to the documentation that came with it.

Sadly, the light comes out of the handpiece in a wide cone, and I want some way to focus it into a actual, collimated laser. I guess I should buy some IR lenses, but I don't know what kind to buy. Any ideas for what to do with it and help with focusing it would be appreciated. The light either comes partially focused out of a handpiece, or totally unfocused directly out of a fiber optic cable.

Specifically, it is a Cynosure apogee-40 long pulse near-infrared alexandrite laser. (mouthful)

not_important - 28-12-2009 at 18:48

This very near infrared light can be treated as ordinary light, most types of glass and clear plastic are transparent to it, standard lenses will focus it although at a slightly different point than they will do so for visable red.

Because of this there are some real safety issues. Your retina doesn't sense that wavelength very well if at all (some people can see it), so your eye won't blink if such light shines in it. However the VNIR light will be focused by the eye lens, potentially frying the retina if power levers are high enough.

I am not a Laser Safety Officer, but I really think that if your laser has a Class 3 or 4 rating, you need to get safety goggles. Do a search for "laser safety goggles alexandrite" to see some example products.

It looks like the main applications are skin treatment and hair removal. It's too long a wavelength for most photochemical applications. You could pick up a LBO crystal and double it to 377 nm or triple to 251 nm, once you go the optics resolved; however that's a bit of an undertaking for a novice as well as additional safety goggles.

[Edited on 29-12-2009 by not_important]

Swede - 30-12-2009 at 09:38

eBay is LOADED with laser "accessories", including safety goggles, focusing devices, power meters, etc that are engineered to function with an IR laser, such as a CO2 device. You can get an idea for what's out there even if you don't buy anything. But ultimately yes indeed, the eyes are critical. Almost anyone can take a skin burn from such a device and tell a nice story, but eye damage is likely permanent and severe. I would not even power it on anymore without proper eye protection.

Do some research on the device itself, find the wavelength it operates at, and get some goggles that will block it.

StevenRS - 30-12-2009 at 10:53

I received the proper eye protection when I purchased it, from the supplier. Two things I am overprotective about : my hearing and my eyes.

Just for interest, what will damage the eyes? Does it require direct exposure to the actual laser beam, or would diffuse radiation also damage the eyes?

I bought a pack of lenses, and will attempt to collimate it later today.

Contrabasso - 30-12-2009 at 12:14

A night vision scope may help with "seeing" the IR for focussing and alignment. Also the cell will take a hit (at cost!) rather than the eyeball at lifetime impairment of eyesight if you accidentally see the beam.

StevenRS - 30-12-2009 at 13:50

The laser shines a red targeting beam through the fiber optic, so one can tell were the laser will end up when pulsed. I was wondering, would the lenses focus the targeting beam too differently to use it to focus the laser?

JohnWW - 30-12-2009 at 15:19

A night vision scope with which to see the IR laser beam? I understand that they are very costly, the better military-grade binocular ones costing something like $10,000 to $16,000 each, and made exclusively by an U$ firm which holds the patents; and that, at least until recently, their $ale was strictly controled by the U$ Govt. because of the big advantage that they confer as regards night vision over the Taliban and Al Qaeda. The U$ Govt., so I understand, at one time by regulation permitted, and may still restrict the better models suited for military use including binocular ones, their sale only to the armed forces of approved friendly countries, and to approved civil airlines and search-and-rescue organizations in those countries. However, at least some models, mainly monocular ones mountable on rifles as sights to avoid the use of artificial light when night-hunting, appear to be now available to the public; see for examples:
http://www.mans-toys.com
http://www.nightvisionscope.com/ http://www.nightvision.com.au http://blog.makezine.com/archive/2008/03/diy_nigt_vision_sco... http://finda.co.nz/night-vision-equipment http://nightvisionscope.net/ http://www.kremlinoptics.com/ http://www.nightvisionexperts.com http://www.angelfire.com/80s/sixmhz/infrared.html http://www.opticsplanet.net/nightvision.html http://www.atncorp.com/ http://www.Cabelas.com http://NightVisionAustralia.com.au http://www.nightvisionUS.com

Night-vision monocular sights for rifles are in particular demand in New Zealand, because of their use in hunting the country's number one introduced pest, the nocturnal Au$tralian brushtail opossum (which are a protected species in Au$tralia except in Tasmania and offshore islands). I hunt and trap them myself. They wreak havoc on palatable native trees (especially Metrosideros species - ratas and pohutakawas) and ripe fruit in orchards, and take the eggs of some smaller native birds. When Howard was in power in Au$tralia, I once felt like sending him through the post dead Au$tralian opossums! There are other nocturnal introduced pests in NZ, like wildcats, wild dogs, ferrets, rats, stoats, weasels, and hares.

If that medical laser outputs at 755 nm, in the very near infrared, it is very likely that some people with particularly dark-adapted vision are able to see the beam. It is possible that this may be enhanced by taking vitamin A supplements.

[Edited on 30-12-09 by JohnWW]

entropy51 - 30-12-2009 at 15:59

Quote: Originally posted by StevenRS

Just for interest, what will damage the eyes? Does it require direct exposure to the actual laser beam, or would diffuse radiation also damage the eyes?

I'm no expert, but when I took a training course on using medical lasers in the operating room we were cautioned that light reflected off steel surgical instruments could damage the eye. FWIW.

not_important - 30-12-2009 at 19:15

Any specular reflection, such as from smoother metal surfaces or the surface of glass and many plastics, is potentially hazardous. True diffuse reflection, off of rough unfinished wood, plain newsprint, and ordinary fabrics, generally is not a problem.

A place where I worked that did laser development was quite serious about both eye protection and avoiding reflective surfaces. The LSO would chase you out of a laser lab if he caught you doing something unsafe, and write up a mark against you. Too many and you were banned from the labs until you went through the safety training again, which only happened when they had enough people (mostly due to new hires) to justify a class; you could find yourself waiting several weeks. One time a researcher pointed to the LSO's hand, he'd forgotten to remove his wedding band. The LSO immediately left the room and removed the ring, and then wrote himself a warning just like anyone else would get.

If the laser is a class I or II, nowadays class 1 or 2, then there's little to worry about. Class 3 is iffy, depends on a number of variables so play it safe. Class 4 is trouble, it's open ended so it goes from "will cause eye damage" to "will set things on fire".

The difference between the sighting beam and laser beam re focusing is going to depend on the lens. It should be close, but it depends on the exact material the lens is made out of.

A digital camera might visualise the beam, depending on the IR filter used in the camera. Most Si based sensors are sensitive out to at least 900 nm, but most also have an IR filter added.

Panache - 5-1-2010 at 18:10

I've been wanting a thread where i can also ask a similar question regarding a medical device i picked up for nothing. However the vintage is somewhat different, i guess its from the 60's, a Watson/Fawkes hearmeroid cauteriser (no idea how to spell those two words). Its a trolley mounted device with a footpedal control pad and a number of dials. i purchased it because when i opened the back of it it was full of huge valves and crazy looking rheostats and stuff (i'm fairly electronically inept so i'm easily impressed).
Anyhows its in working order, there must be something useful in it.
Any ideas? I'll take some photos and post them up.
Regardless i have a device that has probably fried half the asses in Melbourne.

densest - 5-1-2010 at 20:53

Sounds like an RF heating cautery. Big valves/tubes are impressive in a steampunk sort of way :cool:

A look at the front and inside would be fun.

I would guess (without knowledge) that it would be tuned to the diathermy reserved frequency 27.12MHz. Anything pre-1980 would be unlikely to be at a higher frequency.

A great proportion of electronic components are marked with a date of manufacture code. Usually it is YYWW where YY is the last 2 digits of the year and WW is the week number (1-52). If you see a lot of 59xx marked on things, it was probably built early in 1960.

photo's

Panache - 19-1-2010 at 21:27

So the first one is the unit upfront, second one is the control panel with with the foot control thing, third fourth and fifth is rear with panel removed and closeup's, cool valve!!

Image000#1.jpg - 40kB

So two things intrigue me, those things in the fourth image that have like stacks of circle with spacers between them, there is a green one(x3) and a silver one behind the valve.

Also a similar thing except this time a squarish box with what seems like aluminum wire wrapped precisely around it, but coarsely (ie not like a motor)

Does anyone know if i can use this to make psuedoephedrine? That was joke<---Ha!

bquirky - 19-1-2010 at 22:11

Ok hear is a stab in the dark.. Is it a Xray powersupply ?

12AX7 - 19-1-2010 at 22:23

Looks like it would make an excellent induction heater.

The green ones might be selenium rectifiers. The stacked plates are variable air capacitors. The coil is probably an inductor made with silver plated copper tubing.

Tim

Waffles - 21-2-2010 at 20:25

by the way, you can get an extraordinarily cheap (and fun) nightvision IR viewer from thinkgeek.com or other places.

chief - 22-2-2010 at 02:49

755 nm should be visible; we once used the beam of a spectrometer to test the range, and for each one it went to 800 nm, for me even to 804 ...
--> So the beam might or should be visible, although the intensity would be far greater than perceived ...

The damage to visibility can come from light in the mW-range, even 5 mW may do it in a split-second.

Focussing: As long as the light comes from a single resonator it is as if it came from a point-source, and therefore can be focussed; but the "beam quality" ma be not too good ...

75 Joule: Thats something seriously capable; also a medical laser would be made for a lot of use ...
==> Perhaps you could try generating shockwaves at the surface of NH4NO3-crystals (coated with some graphite for the purpose ...)

... maybe they can be set off ...
==> although the 50 ms are quite long, so peak-wattage is limited ... ... maybe it won't work

Then you still could drive the thing with another circuit ... and maybe other lamps/tubes ...

Just report anything interesting here !

What's the wattage or pulse-repetition rate ? Maybe it's at least good for reaching high temperatures ...

[Edited on 22-2-2010 by chief]

aonomus - 25-2-2010 at 14:48

I can't help but notice the roundabout way of viewing the beam to focus it, or to safely deal with IR. Here is a good webstore for optics equipment and supplies: http://thorlabs.com/

More specifically:
IR, UV, Vis viewing cards: http://thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=296
Fluorescent alignment discs: http://thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=3201
Laser safety: http://thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=762

Hope it helps

Panache - 6-10-2010 at 19:07

Quote: Originally posted by 12AX7

Looks like it would make an excellent induction heater.

The green ones might be selenium rectifiers. The stacked plates are variable air capacitors. The coil is probably an inductor made with silver plated copper tubing.

Tim

On that note i took the outer off completely so i could get some better snaps, ok i really only removed it to have a look for capacitors which i discovered (thnks to a thread here) may have Pd in them.

Well well well, i have some 150g so far of pd or pt foil, wooot what a find. As for the other bits any chance anyonbe can id them so i can keep or toss.
Cheers

PICT0004.JPG - 87kB

Ozone - 6-10-2010 at 20:29

"Watson/Fawkes hearmeroid cauteriser"

Funnnny!

Looks like a large RF power supply. Did you try to fire it up before cannibalizing it for loot?

O3

Panache - 6-10-2010 at 20:40

its actually only had one capacitors removed so far otherwise completely intact, that capacitor is one of bank of three identical ones with the loot within them. I'm assuming that capacitor could be replaced now for $50. That was the assumption i made when forgiving myself for removing and investigating it. i have little intention for it as it is quite elegant in its pragmatism.

densest - 6-10-2010 at 22:41

The disks-with-spacers in pict0009 are almost certainly selenium rectifiers. It points to a pre-silicon age

Where did you hear that the capacitors could have Pd in them? It's possible that some small surface-mount capacitors have platinum group metals in the metals on the ceramics, but in old stuff?

Guessing from the size of the air capacitors (maybe 300pF) and air coils (maybe 30microH), it's effectively a 1-10MHz radio transmitter designed to give carefully controlled RF burns. Certain frequencies are/were reserved for diathermy and RF heating in that region of the spectrum.

The people building do-it-yourself cyclotrons would probably really like to use this item...

12AX7 - 7-10-2010 at 07:40

Amazingly, I've heard of *solid* silver varicaps or inductors. Very rare I'm sure.

Almost all varicaps were aluminum, brass and steel construction, and almost all inductors were copper, or at best, silver plated.

Tim

Panache - 7-10-2010 at 12:04

Quote: Originally posted by 12AX7

Amazingly, I've heard of *solid* silver varicaps or inductors. Very rare I'm sure.

Almost all varicaps were aluminum, brass and steel construction, and almost all inductors were copper, or at best, silver plated.

Tim

Hmm, i guess you guys already realize i know nothing about electronics. So much so i have no idea what the last three posts were about. Whats a varicap? Ah wait thats a variable resistor. The ones with the pd/pt in them are not shown, they are mica capacitors. the mica/pd/pt stack is about 1inch by 2inches by 2inches i guess, the foil layers are ~0.0125mm the mica ones thicker. I'm assuming the pt/pd from how the foil behaves and from what i've read. I'm hoping its not silver but as my metallurgy is about as competent as my electronics it may well be, do they make capacitors from silver thin sheet.

Also the big valve thing has a fair thickness of material in it any idea of what is is, i'm assuming nickel.

Now if you think i'm struggling with this rather elegant but old fashioned device, imagine how many questions i will ask next week when my zeiss high resolution EM 10c/cr electron microscope arrives.

Don't fret i have the instruction folder for this one, its says 'west germany' on it. In first few pages i'm reassured that it makes electron microscopy 'easier than it ever has been'
So whats a recifier and is is made from solid selenium?
I honestly didn't know that rf could burn, i didn't really think about it, i assumed there was like a bit nichrome wire, lol. So what actually did the surgeon use in his hand to shoot the rf?

12AX7 - 7-10-2010 at 20:51

Ahh silver mica capacitors ("cap" is short for capacitors; the varicaps are the rotating vane things). Should've left them together, they're nicer as capacitors than metal.

Does the vacuum tube have a part number on it? It's probably made of a combination of nickel, copper, iron, tunsten, graphite, ceramic, tantalum or zirconium, among others. How much depends on what type. It looks like it may be worth something as-is.

A rectifier converts alternating line current to continuous DC, which is needed for the circuit (tubes only work in one direction). Selenium is a semiconductor, used in thin layers between aluminum plates in the stack. They're supposed to smell terrible when they burn out; fortunately I've never had this experience.

RF is an interesting animal. High frequencies don't much like to stay in wires. They tend to jump out at the earliest opportunity. The arc through air is essentially continuous plasma, so it's wonderful for burning the hell out of anything you want. A metal scalpel, charged with RF, burns a hole through anything organic and mildly conductive. RF burns are notorious among radio technicians, because a deep hole is burned out, which doesn't hurt at first because of the nerve damage, but in time, the plug falls out and hurts like hell for weeks, as the deep damage heals. Or something like that.

Tim

Panache - 8-10-2010 at 02:37

damm silver, luckily i only opened one, might keep the unit intact now that i have your description.

Rogeryermaw - 8-10-2010 at 05:24

if night vision can help you with the beam forget the thousands. http://www.qvc.com/qic/qvcapp.aspx/view.2/app.detail/params.... this is just one of hundreds of possibilities that can get you rudimentary N/V for dirt cheap. i actually bought an older version of this and modified it to put the camera on my rifle scope. works like a charm!

Panache - 8-10-2010 at 05:59

Quote: Originally posted by Rogeryermaw

if night vision can help you with the beam forget the thousands. http://www.qvc.com/qic/qvcapp.aspx/view.2/app.detail/params.... this is just one of hundreds of possibilities that can get you rudimentary N/V for dirt cheap. i actually bought an older version of this and modified it to put the camera on my rifle scope. works like a charm!

Now only if you could shoot straight!

Rogeryermaw - 8-10-2010 at 06:21

test me any day bro! bet you'd rather have me on your side

peach - 8-10-2010 at 08:36

Entropy is correct about the reflections. Those lasers are usually crystals pumped with a flash light. They fire very short pulses, but with pretty darn high energies. As such, the reflections from things that would normally be fine with a torch or laser pen can be enough to damage your eyes.

Your eyes don't actually have many nerves in their surface. If they get blasted, you may not even feel it and only notice it later. Welders get that quite often, "sandy eye", where UV from someone else at work has hit their cornea from sides. It's easy to assume that not looking directly at the arc won't be so bad, but the cornea sticks out quite a lot and does soak it up. The result is, sun burnt eyes that start itching like crazy hours later. It can also cause the cornea to become opaque, like a cataract.

You could try removing the hand piece for a start, as the beam may already be suitable from the fibre, or there may be culminating optics inside the laser unit it's self to get the beam into the fibre. Obviously, it's diffused out at the exit to spread it better on the skin, and avoid burning holes in people when it dwells too long in one place; even the pattern out.

As far as uses go;

Start your own beauty salon? As I'm aware of things in the UK, it doesn't actually need a whole lot of paperwork to start shooting people with laZers.

Sintering?

Precision cutting / welding in a bell jar?

Frequency double it up to green?

Use it to burn tape / light matches and add to the already vast numbers of videos on youtube all about igniting matches with $400 laser pens?

Range finder?

Try to make a 3D scanner? There are some incredible ones of those from Leica and the others. It fires the beam and records the return as per a range finder, but then scans the beam using an X/Y mirror array and records one for each point. The result is a scanner that costs tens of thousands, but that can be setup, switched on and then produce a beautiful 3D scan of things as big as cathedrals, accurate down to the millimeter. There are scans from the inside of tombs in Egypt, for instance.

Lots of options.

@12AX7

Have you seen Audionote's site? There's one in the UK and one for Japan. The company was originally Japanese I think.

They are both hard for silver. Seriously hard, with it being a slightly better conductor than copper and there being a lot of talk about there possibly being other conduction differences at work that make the music sound 'better'.

The higher end models make use of things like pure silver capacitors and windings.

And the prices are out of this world. I mean, hundreds of thousands, for a single channel power amp. Then add on, the preamp, diamond / silver cartridges / silver speaker horns, silver drivers and crossovers. Millions for a full stereo setup.

Want!

Nice

[Edited on 8-10-2010 by peach]

12AX7 - 9-10-2010 at 21:47

Quote: Originally posted by peach

@12AX7

Have you seen Audionote's site? There's one in the UK and one for Japan. The company was originally Japanese I think.

They are both hard for silver. Seriously hard, with it being a slightly better conductor than copper and there being a lot of talk about there possibly being other conduction differences at work that make the music sound 'better'.

It's still more bizarre than that.

Lots of people think silver is "too conductive", that it brings out the harshness of some recordings! These people settle for copper, but it has to be oxygen free, single crystal, I don't know what else, material, naturally.

Tim

peach - 9-10-2010 at 23:41

Interesting, as I've also heard them going on about it being sweeter and smoother, like a fine wine or high class escort girl of coarse.

And going on about the crystal structure, conduction bands, electron pools, phase and harmonic distortion in silver versus copper.

I can understand their interest, but not their way of thinking. For instance, strapping $15k's worth of interconnect to a system not worth a whole lot more.

One of the magazines or online blog things did a test where they had 30 audiophile sat in a room, listening to different cables under a double blind setup. There was no statistical confirmation that they could tell the difference. Still, not to let a bit of simple, practical scientific evidence get in the way of discussing the science you agree with or want to sell right?!

Then there's also the real world other side of that cable. That a lot of musicians, while they're bothered about the instruments, don't spend a decade obsessing over wire selection. Quite a lot of them will just pick something up in the shop, think... yeah... that's good, mush it with tone controls, mutes, packing, hang fluffy toys and cigarettes off it, then beat the crap out of it over a few years. Lots of Marshalls come complete with at least a little bit of sick or beer ingrained in the tolex, or burn holes from people putting joints out on them. Case in point, Jimi didn't really care, he just played the mother. There are a lot of people with the same gear as him, and far better, but no one who can recreate what he could imagine up, in his early twenties.

Soooooo, I don't really get the point of trying to eek out details that have been statistically shown, by their own review, to not be detectable in the first place.

There is a point between shit and "SHITTING HELL! That's expensive!", that produces a practical, measurable by your brain, gain. I think Morgan Jones is well onto that idea. His book, Valve Amplifiers, is a killer read, as he's not afraid to blend valve with solid state when he thinks one will do the others job better. A definite read for anyone wanting to learn about analog circuits for audio.

Panache - 12-10-2010 at 19:22

Well the mica capacitors are not silver, the foil dissolves in caustic to form a grey solution, however it also dissolves in conc HCl leaving behind a significant amount of black preicipate/unreacted material. My metalurgy sucks, better get out those underrad texts again. Reading about mica caps (notice the use of electronics vernacular, i'm so radio shack savy now) it appears they are largely either Pt or Pd or some alloy of both.
Anyone got a decent trick for dissolving the difficult to dissolve mica, without needing HF? Peeling it carefully away takes far to long given the brick is like 3000 layers thick.
Just got this baby!!!!! Fucking awesome!! Dork christmas has come early. Its a zeiss em10, however sans the ccd, only $1500.00! Ah how technology devalues. Reading through the documentation however it would appear that intense electron beams can be dangerous, must read more. Perchance does anyone use (or have used) one of these regularily?

zeiss_s.jpg - 61kB

The drawer on the right is a slide out dessicator, so german, i've bought it primarily for the vac pump array (not shown) and the cooling water setup (also not shown), however it seems sad to tear it up for parts so i might leave it intact as a monument.

12AX7 - 12-10-2010 at 21:18

Mica dissolves readily in fluxes, if you don't mind fusing it...

Tim

Panache - 12-10-2010 at 21:42

Quote: Originally posted by 12AX7

Mica dissolves readily in fluxes, if you don't mind fusing it...

Tim

i have some of this

Attachment: Flux Paste.pdf (369kB)
This file has been downloaded 646 times

so what i just mix the two together and heat like crazy?, what happens after that? lol waggh i'm a baby and need to be spoonfed, and i'm lazy.

peach - 13-10-2010 at 00:21

Daaaaaaamn panache!

It certainly would be a shame to tear it to bits. If the worse comes to the worse, you could use it to grill your sausages for a vacuum degassed, fat free breakfast.

{edit}I wonder if the gun can already, or be modified, to weld? Whatever it's welding, it's going to be small and probably thin (foils?), and take a while, but it could be fun to try. And you could offer SM's first in house electron beam welding service. That's how they do all the high end electronics welding and things for satellites; but probably with much, much higher power electron guns to speed it up. When TIG and gas shrouds just won't cut the lumpy mustard.

[Edited on 13-10-2010 by peach]

12AX7 - 13-10-2010 at 07:52

I've seen EBW units before, as in, walked past them... didn't get a look inside or anything.

The trouble is getting enough power. A microscope has to use the least power possible to avoid burning the sample. With voltages around 100kV, it's probably nA-uA. Assuming the same power as a CO2 cutting laser, i.e. maybe 100W in a similarly sized spot, you need 100kV at 1mA. That's a pretty big beam, something most CRTs hardly even do (and they're projecting a bright image over a huge screen!).

100keV also means bremmstrahlung radiation (x-ray) hazard.

Tim

Panache - 17-10-2010 at 01:45

well. i spent a day at the hospital yesterday taking the microscope apart, well that was the intention, however i only got to the 'unhard wiring it from the wall' part. Being a hospital i was concerned, as was the hierarchy regarding the integrity of their power supply. Four 3 core 240V supply leads came into an electrical box containing some sort of relay and a 240-24V transformer. As the room was right next to the blood freezers in the pathology research section it was of considerable importance that i was to remove the microscope without interrupting the supply.
That didn't happen i think, however as it was a saturday at least i didn't have anyone screaming at me. Turns out (perhaps, this my best guess), that the four supply leads coming in were perhaps part of some tricky lock relay for the microscope (it hasn't been used since 1993 and no-one who ever used it is still working there), as the first active lead i removed killed the lights in the room (strange).
Anyone i rather intelligently and cleverly circumvented the system by deciding i didn't really need any of that stuff in the box and just removed the 24V feed (a strange plug) into the instrument.
The instrument is quite epic and taking it apart (it was assembled in the room) is going to be arduous.
Thats a long and completely irrelevant intro to a short question. How does one happily discharge any capacitance within the system so i can safely go about unplugging things without fear of a zap and without the need of wearing rubber gumboots and rubber gloves. Is there a way to test it?

peach - 17-10-2010 at 10:46

I'm surprised they'd let anyone in there, particularly you.

I think the only way to be sure that's empty and safe would be to bridge it with a high ohm value resistor.

The old favourite, a screwdriver over the terminals, could be a bad idea given the amount of current that'll try to get through it if it's charged up to tens or hundreds of thousands.

Once it's done, leave the resistor in place (bolted or soldered on) so it can't charge up again. A lower ohm value will help avoid any building up, once it's electrically dead.

Some of the high voltage capacitors will build up quite a lot of voltage just sitting around, as they scoop it up from the static in the air. A wonky connection on there will make you think it's still safe after it's been sat around Panachest Villa for six months, but could allow it to give yars a nasty zap due to the assumption that the connection has kept it discharged - making it potentially more dangerous than not having it there and expecting it to be part charged.

Long of the short. Screw it on when done!

The typical method for handling high voltages minus the multi-million pound test gear and clothes is to use a chicken stick. Put the thing you're bridge it with on the end of a 100% none conductive pole and jab randomly at the terminals.

Panache - 17-10-2010 at 20:45

Thats the most disturbing thing i've ever seen, why was he like 80's dancing beforehand though?

peach - 18-10-2010 at 00:17

{edit}He's lowering the breaker into place by cranking a handle. Looks like the juice was still on.

This may be a demonstration of why lockout switches with personalized, multiple, colour coded keys are useful when dealing with things that powerful and your staff stood in front of them. That door creates a perfect surface for all the flames and toasty hot plasma to reflect off, into his face. I bet that other guy shit his pants when he saw that happening a few feet from him, I would. The victim probably did have time for that.

[Edited on 18-10-2010 by peach]