Electricuted by strobe

<p>Hello all,</p>

<p>I have a strobe that looks like the attached picture below. Anyway, one not so fine day (today) it stopped flashing, so I took the soft box off of it, and noticed that the strobe tube was detached from its socket. <strong>I turned off and unplugged the unit, </strong>and tried to push it back in place, and got electricuted. Did I do something wrong? Am I not supposed to do something as simple as this by myself without getting killed? Now I'm just scared to touch the whole thing. </p>

<p>Forgot the picture.</p><div></div>

<p>My knowledge of flash electrics is limited, but my respect <strong>huge</strong>. I think it takes a week for a capacitor to entirely discharge (please don't nail me on that semi-educated guess work! - Its meant as "a rough idea of the involved danger") and handling the flash tube with the surrounding wire gets you pretty close to it.<br>

I'd contact my Jinbei dealer for safety instructions, and double check if I'm really following them, if it was my <em>own</em> flash or announce "need for an electrician" at work. </p>

Yeah, I may have done something very stupid, and I

admit that. Wonder how it came loose in the first place.

<p>I'm not familiar with your unit, but the White Lightning X series flashes that I have been using for the last 15 years have a similar system for flash tubes and I have never had the experience you've just had despite replacing flash tubes and occasionally having to push a tube back in after dismounting a soft box. I seem to remember that a reasonable rule of thumb is to turn off and unplug a flash for 20 minutes or so before working on it, although I generally don't wait that long. If this were mine, I would definitely send it in for servicing.</p>

<p>Did you read the instructions first? I just did a little browsing, and I think every single monolight instruction manual says "discharge the flash before . . . . "</p>

<p>Right. I can't discharge the flash without the tube in place, though.</p>

<p>First, I'm glad you're all right. I don't know this strobe, but there is one piece of advice I want to pass on.</p>

<p>A very capable technician told me he never puts both hands across a device that has a powerful capacitor which could possibly be charged. He would work on color CRT monitors, which can deliver upwards of 25,000 volts and a fair amount of current, but with only one hand. The most important thing is to avoid having current pass through your heart.</p>

<p>Hector has it right. One hand in your pocket when working with high voltage/power stuff. You also want to make sure it's unplugged, like you did.<br>

It should have been safe. There must be some capacitance in the strobe unit itself.</p>

<p>Under certain circumstances, a voltage of as little as 30V (DC) can kill. The current across the heart that is lethal is at 100 to 300mA. The average resistance of the human body is about 300 ohms.<br>

Ohm's law tells the story.<br>

I=E/R, so 100mA = E/300V. Thus I = 0.1A = 100mA and can in some circumstances kill you. When a flash tube capacitor discharges, several thousand volts are released.<br>

To borrow the old Brylcreem hair pommade line, a little dab'll do ya!</p>

<p> </p>

If you were electrocuted you wouldn't be

around to tell us about it. Maybe you mean

you were shocked.

<p>Thanks, Craig.<br>

verb (used with object), electrocuted, electrocuting.</p>

1.

to kill by electricity.

 

2.

to <a href="http://www.dictionary.com/browse/execute">execute</a> (a criminal) by electricity, as in an electric chair.

 

Just let it sit for a few days but best practice is to get it to repair technician as the problem is likely not in how the flash

tube pins are sitting in their sockets.

<p>A friend of mine who worked for British Telecom said they had two safety rules. If it's under 50 volts, keep one hand in your pocket. If it's over 50 volts, use an apprentice. Seriously you can only get a shock if some parts of your body complete a circuit between two conductors which have a high voltage between them - including "the general mass of earth". So birds can land on high voltage lines without suffering.</p>

<p>Speaking as an electrical engineer with over 40 years experience in high voltage distribution. The worst shock I had in my life was from a Minolta point and shoot I bought at a car boot sale, and tried to repair the built in flash.</p>

Craig, you are right, that is what I meant. Sorry, English

is not my first language. :-)

Hi Oliver, sorry to hear about your mishap.

 

What I would say first is to see what the owner's manual says about replacing flash tubes. As Andrew indicates, a common instruction is to

wait some time - perhaps10 minutes or so - before replacing a flastube. The general idea is that an internal circuit will bleed off the stored

energy within that time.

 

I think you're right to be afraid of that exposed trigger wire - It ought to be safe after waiting "long enough," but who knows if the "bleed"

circuit may have failed? Personally, I would want to be using a dry towel or glove if I had to touch that trigger wire.

 

In the large chain outfit where I spent a lot of time, we wouldn't want to have that type of design around. We tried to stick with the semi-enclosed flashtube design for exactly the reason you discovered. Our standard gear used semi-enclosed flashtubes, such as the type in the "pro grade" Photogenic and Norman gear - the tube is mounted inside of a more rugged case which can be freely handled without touching the trigger wire.

 

Note that for some reason plug-in flashtubes often seem to want to climb out of their sockets, to the extent that it is normal troubleshooting procedure to make sure that the tube is fully seated. So it's not real unusual for this sort of thing to happen. We had literally thousands of flash systems in our operation, so I have some experience in this sort of thing.

<p>Jinbei Spark II on the morning of April 1st electrocuted you? Really?</p>

Yeah, I thought it was playing a joke on me, but it didn't

feel funny. Not one of those tingling sensations that

make you smile.

<blockquote>

<p>"When a flash tube capacitor discharges, several thousand volts are released"</p>

</blockquote>

<p>Just to set the record straight, that's not true. Flash capacitors are charged to around 400 volts in a modern-ish mains-powered strobe, and around 350 volts max in a speedlight or smaller monolight. That voltage doesn't suddenly increase when the flash is fired.</p>

<p>I'm not underplaying the hazard that flash capacitors pose, but bear in mind that 240 volt AC mains has a peak voltage of close to 340 volts and can deliver several tens of amps before a fuse or trip blows. And to be pedantic, unless Oliver is posting from beyond the grave, he can't have been "electrocuted" - electrocution literally means death by electricity. You got an electric shock Oliver. It's not the same as being electrocuted.</p>

Yes, I apologize for my clumsy English one more time. I did not mean to make people think I was dead when I posted this

thread (although being that it happened on April 1st, that would have been funny in a way).

 

Anyway, I am going to take the strobe to the service center and see what they say. It may well be that I just did not wait

long enough before touching things I should not have been touching. This was a valuable lesson, and I do feel ashamed

of my stupidity, but hopefully this thread will prevent others from making the same mistake, or even from actually being

electrocuted.