Grounds

[Bateau_CX19]

FWIW - DC is actually just as dangerous than AC, just not typically at 12/24v. Dont think for a moment that working with high voltage DC is any safer than high voltage AC. Although, even at these lower voltages but with a high current power source, a direct short can and will cause fires or explosions. Although you can, in theory, touch an AC line at 120v without killing yourself, if you're not grounded, the problem is that ground is a relative thing. Electricity will always find the least resistance path to ground. You are very likely to be at least partially grounded more often than you realize. I have had several painful reminders that AC power is present, a few times even when it was not supposed to be. Power can also sometimes be found on the neutral wire and occasionally even on the ground wire. Higher voltages means higher risk until the point where electricity actually flow through the air looking for a ground source (arc flash).

I think the intent was simply to point out that electricity should be respected and when working on it, it is always good to be educated and experienced. Accidents happen when someone doesn't expect a danger - that is when people die. That is also why it tends to be very new inexperienced (didn't know better) workers and very old experienced (got complacent) workers that get into the most trouble.

Now, lets get back to boating....

[boscoe99]

I disagree with your assessment of the OPs intent. Like moi at some other websites, he is known to be an instigator. Pot stirrer. Troublemaker.

All in good fun.

[boscoe99]

I think the jury is still out as to the lethality of AC versus DC.

[DennisG01]

FWIW - DC is actually just as dangerous than AC, just not typically at 12/24v. Dont think for a moment that working with high voltage DC is any safer than high voltage AC. Although, even at these lower voltages but with a high current power source, a direct short can and will cause fires or explosions. Although you can, in theory, touch an AC line at 120v without killing yourself, if you're not grounded, the problem is that ground is a relative thing. Electricity will always find the least resistance path to ground. You are very likely to be at least partially grounded more often than you realize. I have had several painful reminders that AC power is present, a few times even when it was not supposed to be. Power can also sometimes be found on the neutral wire and occasionally even on the ground wire. Higher voltages means higher risk until the point where electricity actually flow through the air looking for a ground source (arc flash).

I think the intent was simply to point out that electricity should be respected and when working on it, it is always good to be educated and experienced. Accidents happen when someone doesn't expect a danger - that is when people die. That is also why it tends to be very new inexperienced (didn't know better) workers and very old experienced (got complacent) workers that get into the most trouble.

Now, lets get back to boating....

I don't have any experience with high voltage DC, so I won't make any comments on that, other than to just ask for some examples of where high voltage DC might be used? And that is just because I'm curious!

But, yes, I fully agree with everything you're saying. Oh, and about that "complacent" comment... generally I'm not worried about handling 110V AC (changing a light switch, for example) because all it really does it give me a little jingle to remind me that I was being a dumbdonkey. But then there was that time that I was changing a 15a breaker and while holding the 14g wire in my right hand, I inadvertently put my left hand on the case of the box to get a better look... THAT one scared me! I felt it jump straight across my chest! So, yeah, complaceny!

[99yam40]

the highest DC voltage I have been exposed to in a work envirment was around 800VDC at around 70,000 amps in a process making CL2.
I know the magnesium plants used a lot higher amps(over 100,000), but not sure what Voltage they ran at
we wore special rubber boots and tested them every shift before going into the area.
we would walk on to top of the series of Cells to work on some of the instrumentation.

I have seen the damage done when something failed in a system and shorted out the DC.
walls, doors, and windows blown out or metal walls bulged out.
Buss work ripping the insulated supports apart just from the magnetic repulsion of the opposite polarities of the buss work during the high current flows of the short.

But thinking about higher dcv,
a lot of the test equipment for transformers, cables, busses, and switchgear/breakers was DC and it ran in KVs.
always used tested high voltage gloves ,verified no voltage before grounding or touching exposed conductors.
always taped off the areas around the equipment that was to be tested even if that meant also stationing people at every area that someone could be exposed to the test voltages to make sure no one crossed the barricades.

the main reason A/C is used for everyday things is it it easier to transmit over long distances, with less line losses and steps up or down as needed with transformers

Oh yea, 120V AC can be very deadly.
if you touch a live conductor with the inside of your hand/fingers the muscles will contact closing the hand on the conductor and you cannot turn it loose .

if you want to make sure something is de-energized by touching, always touch it with the back of your hand, it can still shock you, but your hand will be pulled away from it and not close on it as the muscles contract due to the electricity flowing thru

[Bateau_CX19]

I think the jury is still out as to the lethality of AC versus DC.

Maybe because most of us don't see much high voltage DC - yet. The automotive industry is pushing towards 48vdc as a standard replacement for the current 12vdc systems and for EV much higher voltages of 400-800vdc will be present. Current kills and current flows depending upon resistance. AC or DC will cause serious grief if current flows across your heart. Across one hand, its just not going to be pleasant and may result in some serious burns. How many of us are going to be comfortable working on our next generation 400vdc outboard motor and battery pack? Almost all of the high voltage DC EV's are isolated, no common ground with the chassis. This is in an attempt to ensure that the potentially lethal, and otherwise just plain dangerous, high voltage is isolated from the rest of the vehicle. Start to consider this in relation to a marine environment where the resistance can be very low due to wet conditions and the potential exists for some major safety issues.

to just ask for some examples of where high voltage DC might be used?

Other places high voltage DC is used? Lots of examples around, especially now with alternate energy sources. The one in Fairbanks, AK is pretty cool. Up to 5200vdc at 12,000 Amps https://library.e.abb.com/public/3c4...rbanks-web.pdf


FWIW, Edison electrocuting an elephant with AC to prove that DC was safer was an outright lie. The elphant would have also died with the same voltage/amperage DC. AC fibrilates your heart, DC stops it. Perhaps it is easier to recover from a stopped heart rather than one in fibrilation, but neither sounds like much fun.

[DennisG01]

Those high-power DC applications are crazy! The pciture of the one in AK looks like something out of a movie.

Walking on top of that type of power? Yeah, I bet you guys did test those boots regularly!

[zenoahphobic]

He seems to be on one continuous trip IMO. He and the xenoman.

Watch it. I may be far away but I do have friends in high places over there!

[zenoahphobic]

I don't have any experience with high voltage DC, so I won't make any comments on that, other than to just ask for some examples of where high voltage DC might be used? And that is just because I'm curious!

But, yes, I fully agree with everything you're saying. Oh, and about that "complacent" comment... generally I'm not worried about handling 110V AC (changing a light switch, for example) because all it really does it give me a little jingle to remind me that I was being a dumbdonkey. But then there was that time that I was changing a 15a breaker and while holding the 14g wire in my right hand, I inadvertently put my left hand on the case of the box to get a better look... THAT one scared me! I felt it jump straight across my chest! So, yeah, complaceny!

High voltage DC used in trams and trains, so plenty of bare lethal wire spun all over the place.

[99yam40]

Walking on top of that type of power? Yeah, I bet you guys did test those boots regularly!

if this is a response on what I wrote, the cells I mentioned were not battery cells, they were the brine cells that the DC current flowed thru to create CL2,H2,& caustic