Safety Practices, General and Ultra-High Voltage

[richwalters]

Perhaps I should have mentioned for H.V work a cushy posh chair which conducts is the last thing one wants.........conflict with static yes.....to me a conductive arm band as is so often worn by assemblers to me in the type of R&D I do is the equivalent of a funeral in an electric chair.
The middle ground ? 1000000000ohm resistor ?

richj

[Tweeker]

One help when working with semiconductors might be to control room humidity. Very dry rooms will cause both more ESD and more corona issues. It may or may not also mean less dust, which has killed more than a few people. At high voltage you dont actually have to touch a conductor to be hit, it can reach out and grab you. It can reach a very long way if its dusty. I know of a man killed opening a dusty 460V panel.

Lots of caveats apply here, too wet is worse, and condensation is bad.

[richwalters]

The worst discharge I get is getting out of my Ford.....I'm absolutely licked when turn round to lock it....this far worse than any bolt I've had in my lab. A strap from underframe to ground doesn't last long. A non tribute to Ford in all these years not finding a better seating fabric.

richj

[ThermoMan]

GFI
In electrical installations GFIs operate to disconnect a circuit whenever they detect that the flow of current not balanced between the phase conductor and the neutral conductor. The presumption is that an imbalance might represent a current leak through a person's body, a person who is accidentally touching the energized part of the circuit, who is grounded, and who is therefore about to receive a potentially lethal shock. These are designed to disconnect quickly enough to prevent these shocks.
Isolation transformer
An isolation transformer, often with symmetrical windings, which is used to decouple circuits. An isolation transformer allows an AC signal or power to be taken from one device and fed into another without electrically connecting the two circuits. Isolation transformers block transmission of DC signals from one circuit to the other, but allow AC signals to pass. In electronics testing, troubleshooting and servicing, an isolation transformer is a 1:1 power transformer which is used as a safety precaution. Since the neutral wire of an outlet is directly connected to ground, grounded objects near the device under test (desk, lamp, concrete floor, oscilloscope ground lead, etc.) may be at a hazardous potential difference with respect to that device. By using an isolation transformer, the bonding is eliminated, and the shock hazard is entirely contained within the device.
This material is from Wikipedia and looks to be pretty spot on as best I can tell.

[jackinnj]

Originally posted by richwalters
The worst discharge I get is getting out of my Ford.....I'm absolutely licked when turn round to lock it....this far worse than any bolt I've had in my lab. A strap from underframe to ground doesn't last long. A non tribute to Ford in all these years not finding a better seating fabric.

richj

This exact topic was discussed by Click and Clack on Car Talk two weeks ago.

[DigitalJunkie]

I hate automotive upholstery.. I don't know what magical static-thread they weave it with...BAH! I get 'bit' everytime I get out of a car...It's obnoxious.
My latest trick,grab the frame of the door BEFORE I get out..it's been working for me,so far.

[johnthedoctor]

Good point about the jewellry. I was working on a car and my hand got stuck between the battery and the chassis. Took a while to free it, with my chromed watch bracelet merrily discharging the battery and getting hot and hotter. Took months for the burns to heal.

One bit of advice I was given long ago was only wear cotton if working with HV or gas. It doesn't stick to your skin in cases of extreme heat unlike manmade fabrics.

What size isolation transformer is best. Back in my TV days I had a massive one but always wondered if it was too big. All that current available to harm me. Is one just big enough to handle the load of the project safer?

[eforer]

Could someone post some suggestions on a isolation transformer GFI combo. Specifically a link to a suitable, safe transformer and a little guidance as to setting it up with a GFI?

I'm beginning my first tube project soon and I want to take all the precautions possible.

[gmphadte]

U need to ask in the correct forum.

Gajanan

[eforer]

What forum would that be? I figured it was a safety issue that might be useful for others to learn about as well. I apologize.

-EF