Be careful with these things…
“A North Carolina man who was working on a new Tesla Motors auto charging station in Virginia has died.”
“NC man working on Tesla charging station in Va. found dead”
http://www.wral.com/nc-man-working-on-tesla-charging-station-in-va-found-dead/14841000/
Ok. Why post this? Seems someone made a mistake and paid for it.
It seemed relevant. We have a Tesla charging station. People work on it.
Yes, but we have lots of things that people work on. And if they do something stupid with those things they can end up dead as well. From the article there is no indication the cause was some design issue with the Tesla charger.
Heck, a decade or so ago, I was working at DFW when one of their maintenance workers turned himself crispy just changing a light bulb… Granted it was a bulb for the runway lights, but never the less. The problem wasn’t the design of the light bulb.
Although most of us are familiar with the hazards and operating characteristics of vehicles and light sockets, car charging stations, especially a Tesla charging station, are new. Besides, if I saw a news article about someone getting killed in a Bridgeport, I might post that, too.
Richard,
An understandable cautionary tale to be aware of; my only thought is that the article really doesn’t elaborate beyond the title itself so it was not worth clicking on at this point. If there is some actual forensic engineering details behind this, I will be interested in hearing it.
Walter, the bulb incident is also unfortunate, but also a commentary about how most humans die of rather mundane causes rather than plane crashes and terrorist attacks. It does almost beg the old joke of how many [fill in the blank]'s does it take to change a light bulb - safely…
JAG “OSHA Compliance Training for Sea Pirates” MAN
I know the article was sparse. I actually read several articles, and selected the most informative that I could find to post.
This has little to do with the fact that it is a Tesla charging station. All electrical should be powered off and locked out before work begins. This is one of the most basic aspects of occupational health and safety: lock out/tag out.
This light bulb was’t your mother’s light bulb. It was one of the bulbs that allow pilots to see the runway from miles away. It was powered by a 5KV circuit with essentially unlimited current available. They are supposed to change the bulbs while wearing full rubber protection suits. But it was August in Texas and he rolled the dice.
Walter,
This light bulb was’t your mother’s light bulb.
I realize that - my point is that humans are typically poor at risk assessment when weighing in terms of more “spectacular” news making incidents. My guess is it didn’t make the papers at all, but we still spread supermarket checkout line magazines full of how some [random actress] has gained 5 pounds or you could be kidnapped by polar bears.
All electrical should be powered off and locked out before work begins. This is one of the most basic aspects of occupational health and safety: lock out/tag out.
Mathew, even that may not be a sufficient precaution. Do Tesla stations have any capacitors in them that could be live even with the power shut off? When the power is cut for a station, is it obvious that it is not live? Do they have some equivalent GFCI when it rains? (these stations are located outdoors) I am not sure about charging stations specifically, but I know some equipment is like that.
I make no (or damned few) assumptions.
JAG “Repelling All Boarders With a High Voltage Probe” MAN
Ken showed me the insides of our charging station several months ago. I was impressed by how few parts are actually inside. It’s mostly just air space. Of course, even small capacitors could give a nasty jolt.
That isn’t the kind of station that they are talking about. I believe they
are talking about the superchargers… IF that is the case, he was dead
before he hit the concrete. 120KW -will- kill you very rapidly.
Still it should have been locked out/tagged out before starting work.
Not to stoke the fire, but anything that puts about 10-100mA through your heart at 60Hz will kill you. Doesn’t matter if it can supply 100mA or 1000A. Higher voltage just makes it easier to produce that current flow through whatever path it wants to flow.
Remember to lock-out, tag-out and ALWAYS check if you walk away from a project. Never know who might have flipped something back on. Poke at stuff with one hand in your pocket and not leaning against anything if necessary.
I think you understand my point. 
Every piece of high voltage equipment I’ve been around (mainly pumping and water/wastewater treatment facilities) has well-documented shutdown procedures for the reasons you’ve mentioned (it should be noted that startup is generally just as important). I don’t know enough about the NEC or charging stations to know what the set up is, but that isn’t important for safety: it’s electric and anybody working on it should be acutely aware of its hazards – it’s their job.
Mathew,
I think you understand my point.
Yes, and I believe you understand mine as well. Your information is correct, but it doesn’t hurt to elaborate further as you did in helpfully pointing out that proper startup procedures are important too.
I don’t know enough about the NEC or charging stations to know what the set up is, but that isn’t important for safety
Huh?
Somehow I know you are trying to convey the correct idea, but I find this statement confusing.
It isn’t important to know what the setup is?
I disagree.
The more you know about the system, the better educated you are on how to work around it safely so that you can infer unspecified hazards and deal with complications appropriately.
None of us were there when that fatal accident happened. Was it a design issue, defective manufacturing, poor training, carelessness? A combination of more than one of these? I don’t know and neither does anyone else here at this point
anybody working on it should be acutely aware of its hazards – it’s their job.
In the case of the aforementioned Tesla accident, I tend to agree, but something could have been miswired. Even a “ground” wire can carry a potential voltage if there is a screw up somewhere - personally I verify with a voltmeter, a live circuit detector, or someone I don’t like.
But evidently the unfortunate victims did not follow enough precautions (or the proper ones) and it appears that Richard is pointing out that we should be cautious around even a general consumer use tool such as that one as I don’t believe any of us are Tesla certified charge technicians. (so not our “job” per se so much as a damn good idea for self-preservation and keeping DMS safe)
I’m not trying to be difficult, Mathew, it just comes naturally to me because of how I was raised and trained so nothing personal.
JAG “Black Adder of the Safety Compliance Team” MAN
BTW, speaking of me being a persnickety technical bastard, I am getting tired of people misquoting the lethal levels of electrical current passing through the human heart. I hear everything from 1 milliAmp to an Amp - below is the generally accepted chart from OSHA: (100 mA is a general rule of thumb for minimum current required but it is shown as low as 50 mA here - YMMV (Your Mortality May Vary)
https://www.osha.gov/Publications/3075.html
Bear in mind these are ranges and the actual current and lethality depends on the effective resistance of the human body which is a non-linear voltage / current dependency which also includes time as a factor as indicated in this more complex graph here: (just trust me and click on the link below - it is VERY interesting)
I badly phrased what I was getting at. I was trying to say that you don’t have to be a Master Electrician to assess the critical safety points for that job (turn off, discharge the power systems, etc.), and that a Master Electrician theoretically has the knowledge to not only identify those risks (like a layman safety officer could do) but mitigate them appropriately.
We’re both preaching to the choir here, I think you’ve hit the nail on the head Rev. Jagman.
Wearing Faraday cage? Wuss! 
Mathew,
I badly phrased what I was getting at.
Ah… I figured there was some kind of miscommunication going on.
I was trying to say that you don’t have to be a Master Electrician to assess the critical safety points for that job (turn off, discharge the power systems, etc.), and that a Master Electrician theoretically has the knowledge to not only identify those risks (like a layman safety officer could do) but mitigate them appropriately.
Okay, much clearer - thanks!
We’re both preaching to the choir here, I think you’ve hit the nail on the head Rev. Jagman.
Heh heh… Reverend JAGMAN… I like it!
Thank you for tolerating my sermonizing in a civil fashion…
JAG “Let Us Now Read From The Book of OCD Chapter 4 Verse 19” MAN
The way the article reads, it would appear he was an electrical contractor. Safety is in training, if you do not know what your working with your rolling the dice. I work on a lot of drives, some being Medium voltage, I know safety procedures for them to determine if it safe. It is your own responsibility to determine if it safe,it’s your life. If I do not feel comfortable I will get more info before proceeding. Same sentiment others should take. Remember Charlie.
