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Lockout-Tagout

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Re: Lockout-Tagout

#41

Post by unlinked_dll »

taneq wrote: post #28
caseymarquis wrote: post #26

Earlier quoted context omitted.

After working on high voltage circuits as a lineman for a couple years, and currently writing software for industrial machinery and regularly working in industrial machining cabinets, I think that applying the same level of precaution used for mining to doing minor work on a 100V circuit is being a bit overzealous. To be fair, you're never going to get hurt by being superfluously safe, but at the same time I don't ex…

Honestly if our mains was 110V rather than "240V" (read 250-260V thanks to all of the rooftop solar in our area) I'd probably be a bit more casual about it. I've been nipped by ~100V from poor earthing and it's not that bad. 240V hurts.

I've gotten burned by changing light bulbs without turning off the switch; garnering me the nickname "Uncle Fester" by my family (in my defense - the light bulb was out and I wasn't thinking) and that shit definitely hurts.

I've also been burned debugging a power supply for a GSM amplifier used in the test harnesses for a semiconductor fab (this time was carelessness, the power supply rails weren't taped off since I was probing it attempting to find a fault on the point-to-point wiring) that was powered at 240V and holy hell I do not recommend doing anything that stupid. If it doesn't have a safe way to repair, buy a new one.

Re: Lockout-Tagout

#42

Post by Semiapies »

Intermernet wrote: post #5

This is unofficially gaining a 3rd step: "Try out". Sometimes people fail to properly lock and tag, and it's usually worth physically testing that the equipment is actually disabled before someone is injured or killed due to incorrect locking / tagging. EDIT: This is obviously mentioned in the article! Mea culpa ;-)

Hey, it definitely won't kill anyone to reiterate it.

Re: Lockout-Tagout

#43

Post by lb1lf »

taneq wrote: post #28
caseymarquis wrote: post #26

Earlier quoted context omitted.

After working on high voltage circuits as a lineman for a couple years, and currently writing software for industrial machinery and regularly working in industrial machining cabinets, I think that applying the same level of precaution used for mining to doing minor work on a 100V circuit is being a bit overzealous. To be fair, you're never going to get hurt by being superfluously safe, but at the same time I don't ex…

Honestly if our mains was 110V rather than "240V" (read 250-260V thanks to all of the rooftop solar in our area) I'd probably be a bit more casual about it. I've been nipped by ~100V from poor earthing and it's not that bad. 240V hurts.

-During the annual EE safety refresher course I take at work, the instructor makes a point of the fact that during domestic work, the electric shock is often merely the trigger for the real injury; you get zapped, then fall from the ladder you were on or whatever.

(We have 240VAC mains, but I guess an unexpected jolt of 110VAC would be sufficient to make me jump...)

Re: Lockout-Tagout

#44

Post by taneq »

dgemm wrote: post #39
taneq wrote: post #9

After working in mining for a long while, where this kind of isolation procedure is standard and is taken very seriously (pretty much any breach of procedure is an instantly firable offense) it's terrifying coming back home and seeing people working on house wiring etc. with nothing more than a turned-off circuit breaker protecting them from electrocution or other injury. I've seen some trades start to pick up isolat…

I worked in mining as well and it's often terrifying watching the stuff that goes on all day at every urban construction site, even the things you can see from street level. Construction workers that stand directly below suspended crane loads in order to guide them down to the ground is something I see constantly and makes me nervous just to watch. If you tried anything like that at any of the mines I worked at you w…

I've seen some things on mining construction sites that'd curl your toes, too. Once I was troubleshooting a cabinet and the light changed. I looked up and there was an EWP with two guys pulling cables, about 10m directly above me. No warning, no marked drop zone, no communication. On the same site I saw a 20 ton piece of equipment get lifted into position, double lift between a gantry crane and a Franna, again no drop zone or anything, just one guy coordinating with hand signals. It worked out OK, but yikes.

Re: Lockout-Tagout

#45

Post by symplee »

Any software patterns comparable to this?

(Would help to have a use-case example. And how the pattern helped Vs. what was being done before)

Re: Lockout-Tagout

#46

Post by taneq »

unlinked_dll wrote: post #41
taneq wrote: post #28

Earlier quoted context omitted.

Honestly if our mains was 110V rather than "240V" (read 250-260V thanks to all of the rooftop solar in our area) I'd probably be a bit more casual about it. I've been nipped by ~100V from poor earthing and it's not that bad. 240V hurts.

I've gotten burned by changing light bulbs without turning off the switch; garnering me the nickname "Uncle Fester" by my family (in my defense - the light bulb was out and I wasn't thinking) and that shit definitely hurts. I've also been burned debugging a power supply for a GSM amplifier used in the test harnesses for a semiconductor fab (this time was carelessness, the power supply rails weren't taped off since I…

Burned or zapped? Light bulbs get thermally hot but glass is non-conductive.

I haven't personally been bitten by 240V but from people I've talked to who have, I don't intend to chance it happening.

Re: Lockout-Tagout

#47

Post by matt-attack »

zaarn wrote: post #36
ebiester wrote: post #13

Earlier quoted context omitted.

How would you recommend people working on their own house implement anything more than turning off the circuit breaker? (I'm not doing anything electrical in general, but sometimes small fixes are necessary for home owners.)

What I learned when doing electrical work in germany, the procedure for safe electrical working is as follows: - Switch off (at circuit breaker) - Prevent switching on (lock the breaker) - Check voltage free (multimeter cleared for 230V/120V operation with long, isolated test leads) - Ground and short (put a plug into the socket connecting earth, live and neutral, you can DIY that at home safely by cutting open an un…

Step three, don’t forget to unplug your short circuitter before flipping back on the breaker.

Re: Lockout-Tagout

#48

Post by ganzuul »

symplee wrote: post #45

Any software patterns comparable to this? (Would help to have a use-case example. And how the pattern helped Vs. what was being done before)

Database operations. ACID compliance. Could also be safety critical to keep your state stateful.

Re: Lockout-Tagout

#49

Post by zaarn »

matt-attack wrote: post #47
zaarn wrote: post #36

Earlier quoted context omitted.

What I learned when doing electrical work in germany, the procedure for safe electrical working is as follows: - Switch off (at circuit breaker) - Prevent switching on (lock the breaker) - Check voltage free (multimeter cleared for 230V/120V operation with long, isolated test leads) - Ground and short (put a plug into the socket connecting earth, live and neutral, you can DIY that at home safely by cutting open an un…

Step three, don’t forget to unplug your short circuitter before flipping back on the breaker.

Usually you just follow this list in reverse; from bottom up and undoing what you did.

Re: Lockout-Tagout

#50

Post by jjeaff »

lb1lf wrote: post #43
taneq wrote: post #28

Earlier quoted context omitted.

Honestly if our mains was 110V rather than "240V" (read 250-260V thanks to all of the rooftop solar in our area) I'd probably be a bit more casual about it. I've been nipped by ~100V from poor earthing and it's not that bad. 240V hurts.

-During the annual EE safety refresher course I take at work, the instructor makes a point of the fact that during domestic work, the electric shock is often merely the trigger for the real injury; you get zapped, then fall from the ladder you were on or whatever. (We have 240VAC mains, but I guess an unexpected jolt of 110VAC would be sufficient to make me jump...)

110v or 240v will kill you dead where you stand. But it's not really about the voltage. The higher the voltage, the easier it is for the electricity to ground out through you. But it only takes a few milli-amps across the heart to kill you. A household line can deliver 10-20 amps.

Luckily, human skin is not highly conductive and neither are rubber soled shoes.

So if you are taking proper precautions and not kneeling on a wet floor while using all metal tools on bare wires when someone flips a breaker back on, then your risk is rather minimal.

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