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Fun with cheapo multimeters. "If the [multimeter] fuse is rated to 250 volts, and the meter's rating says 750-volt cat... anything... then something is seriously wrong." https://www.youtube.com/watch?v=OEoazQ1zuUM&t=352s It measures 750V just fine. However if you turn it from volts to Ohms, something magical happens! (This is a big part of the difference between a $10 multimeter, and a $200/$300 name-brand industrial multimeter. And people have died due to this sort of thing. Those crappy meters are legal to sell in the US.) Three-Phase fucked around with this message at 02:26 on May 21, 2016 |
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May 21, 2016 02:22
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Three-Phase posted:Fun with cheapo multimeters. "If the [multimeter] fuse is rated to 250 volts, and the meter's rating says 750-volt cat... anything... then something is seriously wrong." Harbor Freight gives those meters away with any purchase sometimes. I got one.
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May 21, 2016 04:38
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Becsuse as a homeowner I use a multimeter about twice a year, $200 is a lot for a tool thst gets used very little. What I Do is make sure when I deal with electron piping that I am careful and mindful of what I am doing and 2x check any equipment or things I touch to live items.. I make sure my probes are in the right spot and my switch is in the right area. I also inform my wife that the main breaker is here and if I'm in distress she needs to flip it, and under no circumstances is she to grab me becsuse that won't solve aything.
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May 21, 2016 13:46
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How often will anyone who is not an electrician, even have access to more than 220V? Most people will use multimeters to troubleshoot their brake lights. The harbour freight coupon special is great for that
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May 21, 2016 13:57
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Nitrox posted:How often will anyone who is not an electrician, even have access to more than 220V? Most people will use multimeters to troubleshoot their brake lights. The harbour freight coupon special is great for that anyone with the balls and the lack of good judgement  
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May 21, 2016 14:05
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http://i.imgur.com/xBNmyXa.gifv
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May 21, 2016 14:24
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sweet
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May 21, 2016 14:26
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When that thing got to 88 miles per hour they saw some serious poo poo.
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May 21, 2016 15:20
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Mario kart looks good these days.
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May 21, 2016 15:25
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I fully admit I only watch F1 for the cool crashes.
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May 21, 2016 15:27
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Make this move legal like ASAP and I might watch Formula-whatever-number.
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May 21, 2016 15:38
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ReagaNOMNOMicks posted:Make this move legal like ASAP and I might watch Formula-whatever-number. They don’t even allow refuelling at pitstops now, in part because of stuff like this.
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May 21, 2016 15:40
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Platystemon posted:They don’t even allow refuelling at pitstops now, in part because of stuff like this. Imho F1 pit crew should always be fat and on fire. 
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May 21, 2016 15:50
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Svartvit posted:Imho F1 pit crew should always be fat and on fire. Man, everyone must have been pissed off at that guy after.
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May 21, 2016 16:27
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Svartvit posted:Imho F1 pit crew should always be fat and on fire. tire guy was outta there
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May 21, 2016 16:48
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poo poo like this is the only reason I want F1 to bring back refueling
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May 21, 2016 17:03
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Platystemon posted:They don’t even allow refuelling at pitstops now, in part because of stuff like this. So, uh, how does refueling work now? Are the races just shorter or something?
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May 21, 2016 17:18
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VectorSigma posted:So, uh, how does refueling work now? Are the races just shorter or something? They have to start the race with enough fuel for the entire race. If they need to refuel, they have to take it behind the wall, into the garage.
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May 21, 2016 17:25
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I think this belongs here. Some of them have been posted for sure, but it's a great collection. https://www.youtube.com/watch?v=GGoGvZZjkOo
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May 21, 2016 17:34
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RabbitWizard posted:I think this belongs here. Some of them have been posted for sure, but it's a great collection. Those prevent.it ads are hosed up. Holy poo poo.
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May 21, 2016 18:00
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Deteriorata posted:They have to start the race with enough fuel for the entire race. This just sounds like trading one problem for another.
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May 21, 2016 18:03
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VectorSigma posted:This just sounds like trading one problem for another. It's easier to crash-proof the fuel cells in the cars than spill-proof refueling in the pits. The new problem is smaller than the old one, so it's an improvement.
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May 21, 2016 18:10
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Since they made the switch to non-refueling races, I don't recall any major incidents involving a fuel fire (sometimes an engine catches fire mid-race, but I've never seen in spread beyond the chassis). If I recall the numbers correctly the cars carry a maximum of <40 gallons of fuel and with their crazy hybrid engines get something approaching 5 mpg (which doesn't sound much but consider the car's average speed is >110 mph and top speed well over 200 mph.) F1 is probably the safest it's ever been at the moment, considering you've got Alonso walking away from a crash like this with minor injuries. Hobnob fucked around with this message at 18:34 on May 21, 2016 |
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May 21, 2016 18:28
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Nitrox posted:How often will anyone who is not an electrician, even have access to more than 220V? Most people will use multimeters to troubleshoot their brake lights. The harbour freight coupon special is great for that 240V is common on farms and you do need a good multimeter to troubleshoot issues with dryer fans, mills, seed cleaning equipment, etc. It seems like you're always rewiring live cable. You don't have time to find the breaker that could be 100 ft away. You just do it live and make sure that you don't earth. Though you always end up making a mistake. Yes, 240V hurts like a motherfucker. 110 is like a kiss on the cheek from the love of your life compared to 240. I'd never mess with anything over 240. It's just not worth it unless you're getting paid.
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May 21, 2016 18:50
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May 21, 2016 19:25
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Hobnob posted:Since they made the switch to non-refueling races, I don't recall any major incidents involving a fuel fire (sometimes an engine catches fire mid-race, but I've never seen in spread beyond the chassis). If I recall the numbers correctly the cars carry a maximum of <40 gallons of fuel and with their crazy hybrid engines get something approaching 5 mpg (which doesn't sound much but consider the car's average speed is >110 mph and top speed well over 200 mph.) So what you're saying is that if I want to experience an awesome car crash, I should do it in a Formula 1 car.
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May 21, 2016 19:53
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tater_salad posted:Becsuse as a homeowner I use a multimeter about twice a year, $200 is a lot for a tool thst gets used very little. $200 for a tool you don't use very often is a lot. But $50 for a tool that you can be sure isn't going to catch fire and explode while you're holding it no matter the circumstances even if by accident, is well worth it imo.
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May 21, 2016 20:53
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mostlygray posted:240V is common on farms and you do need a good multimeter to troubleshoot issues with dryer fans, mills, seed cleaning equipment, etc. It seems like you're always rewiring live cable. You don't have time to find the breaker that could be 100 ft away. You just do it live and make sure that you don't earth. Though you always end up making a mistake. In the USA, regular mains is 110V, which is the phase/neutral difference from a three-phase 230V system, the 230V are only used for huge appliances. In Europe, regular mains is 230V, the three phase system used for big appliances is 400V. I don't think getting a 400V jolt is fun.
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May 21, 2016 21:26
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Wile E. Coyote approved.
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May 21, 2016 22:10
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mostlygray posted:240V is common on farms and you do need a good multimeter to troubleshoot issues with dryer fans, mills, seed cleaning equipment, etc. It seems like you're always rewiring live cable. You don't have time to find the breaker that could be 100 ft away. You just do it live and make sure that you don't earth. Though you always end up making a mistake. Everyone I ever knew who worked in industry had plenty of stories about people working on 110 whose hands involuntarily clamped down on the lines when they were shocked and died from the prolonged current.
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May 21, 2016 22:27
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Even our instructors aren't immune to OSHA! We were holding a two-day class this weekend at our institute with the only two instructors who were available, both of whom are incredibly sickly: one has weekly chemotherapy and often seems to be on death's door every day, and the other is struggling with a single usable arm due to severe damage in a car accident that got infected (followed by skin grafts that are being rejected). Today, only the guy with cancer showed up and we got no calls from the one-armed bandit or his wife telling us where the guy is. He was supposed to be flying up from Miami so they could trade off halfway through the day (as neither of them is really in any condition for a full 8-10 hour day of classroom teaching). Finally, we got a call back from his wife. Turns out yesterday he decided to climb into one of his cranes for whatever reason....with only one usable arm. He promptly fell trying to climb into the cab and couldn't put out his good arm to break his fall because it would probably end up broken, so he landed directly on his face.
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May 21, 2016 23:22
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tater_salad posted:Becsuse as a homeowner I use a multimeter about twice a year, $200 is a lot for a tool thst gets used very little. I did a little more digging - you can get a little Extech meter for about $60, and there is a clamp-type Fluke that runs about $115 on Amazon. There are also a ton of sub-$20 meters from brands nobody has ever heard of. I would be extremely cautious using any multimeter that's under $50. As far as the $10 multimeter goes - if it said on the meter "Hey, I should only be used up to 240V and not on industrial or commercial circuits", that would arguably be much better. The problem is when it says it can safely measure up to 700+ volts, and there's a dinky fuse inside rated at 250V. Also for a home circuit, generally if there's a short circuit that you make during measurements (like measuring voltage while the probes are plugged into the ports for common and current) the short circuit current flow is a lot less than you might have than if you short an industrial or commercial power system out. mostlygray posted:Yes, 240V hurts like a motherfucker. 110 is like a kiss on the cheek from the love of your life compared to 240. I'd never mess with anything over 240. It's just not worth it unless you're getting paid. We have a lot of 120V DC systems, and the problem there is that people have volt-alert pens that don't detect DC. Depending on where you are in the world 400/240V, 480/277V, and 600/347V systems are also common for small industrial equipment that can really thump you. Highest I ever directly measured off a drive was around 700V AC, and the highest current (different equipment) was over 4000A AC on large busbars. (I had 3000A Dran-Flex probes we ran to about 130% capacity, I think the Dranetz people had a "It's possible, but not recommended" comment when I mentioned how far I pushed those flexible probes!) The 700V measurements scared me more than the 4160V systems because you took direct multimeter measurements, with the 4160V system you had potential transformers built in to step the 4160V down to 120V. Three-Phase fucked around with this message at 01:05 on May 22, 2016 |
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May 22, 2016 00:58
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chitoryu12 posted:Finally, we got a call back from his wife. Turns out yesterday he decided to climb into one of his cranes for whatever reason....with only one usable arm. He promptly fell trying to climb into the cab and couldn't put out his good arm to break his fall because it would probably end up broken, so he landed directly on his face.
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May 22, 2016 01:47
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dis astranagant posted:Everyone I ever knew who worked in industry had plenty of stories about people working on 110 whose hands involuntarily clamped down on the lines when they were shocked and died from the prolonged current. For sure. That's why you always wear good boots and work with only one hand on equipment that's live. Tuck the other hand into your belt so you don't forget. That's pretty non OSHA, but it tends to work. At least you only burn your hand that way. Speaking of being un-isolated, my father was welding in the hopper of a combine once and I was sitting below turning the welder off and on for him. The whole combine was grounded. He forgot, and grabbed the rod to change it instead of telling me to turn it off first. I heard the sound of a grounded out rod from the machine and shut it off. He said "thank you". He was getting 100 amps through his body and out his rear end and couldn't let go. He's lucky he didn't die.
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May 22, 2016 02:22
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mostlygray posted:Just don't forget. I knew a guy who forgot, and he almost died! Things like this are why we have standards.
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May 22, 2016 03:16
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mostlygray posted:For sure. That's why you always wear good boots and work with only one hand on equipment that's live. Tuck the other hand into your belt so you don't forget. That's pretty non OSHA, but it tends to work. At least you only burn your hand that way. Glad your dad's OK, but he certainly wasn't getting 100A through his body. (Assuming a really low-end 250 Ohms resistance between your dad's body and ground, you'd need 25kV to push that much current through. Plus that would be 2.5 megawatts going through your dad, so he'd probably be burned to a crisp very quickly if he did't literally blow apart.) His shock was probably in the milliamps, but small currents like that can still paralyze a person's movement/breathing or fry their heart. Lethal, but not as "spectacularly lethal" as contact with higher voltages. Frinkahedron posted:Harbor Freight gives those meters away with any purchase sometimes. If you're working on hobby electronics, car stuff, and things that generally can't kill you, I think you'll be OK. I think one of the other concerns about super-cheap meters are the quality of the probes, like if they use high-quality insulation or not. That's as important as the quality of the meter itself. Three-Phase fucked around with this message at 03:58 on May 22, 2016 |
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May 22, 2016 03:53
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Multimeter talk reminded me of this old one about a Navy sailor who fatally electrocuted himself with the 9-volt battery in a multimeter. http://www.darwinawards.com/darwin/darwin1999-50.html
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May 22, 2016 04:48
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Three-Phase posted:Words Agreed, if I was dealing with 750v I'd be sure to make sure I"m using a tester that wont blow up in my face, and was worth some money. If the fuse is rated at 250v how can they safely say that the meter is good for 750v? I'd think that UL or similar would have an issue with that, yes it's not DESGINED to be used in that mode when measuring voltage, but it can easily happen.
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May 22, 2016 05:25
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tater_salad posted:Agreed, if I was dealing with 750v I'd be sure to make sure I"m using a tester that wont blow up in my face, and was worth some money. Yes, yes they would. Which is why such meters don't have any sort of official certification whatsoever (they closest they get is a "China Export" mark that looks suspiciously similar-yet-not-quite-the-same-as a euro CE mark).
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May 22, 2016 06:05
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Jabor posted:Yes, yes they would. Which is why such meters don't have any sort of official certification whatsoever (they closest they get is a "China Export" mark that looks suspiciously similar-yet-not-quite-the-same-as a euro CE mark). China Export is just a snappy backcronym. The CE mark only means the manufacturer promises that the product follows European health and safety directives, which is required for sales. It's not protected. Only of you start faking certification numbers you get in trouble.
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May 22, 2016 09:18
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