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| Big Clive's "Trashy" meter, unboxed ( Duratool D03047 multimeter ) |
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| David Aurora:
--- Quote from: Fungus on April 27, 2023, 04:32:15 pm --- --- Quote from: David Aurora on April 27, 2023, 03:27:59 pm ---I turn the switch off before changing them, because I'm not a fucking idiot. To each their own though I guess :-// --- End quote --- What if it's a two (or three) way switch and you don't know if it's on or off? Do you rewire your house first? --- End quote --- If it was really a safety concern (which it's not, but I'll play along and pretend we're talking about a broken bulb where you need to grab the base or something) I'd flip the breaker or grab a chicken stick. I'm guessing this is the bit where you remind us you're a hero and you'd do it with your teeth because you're super tough and cool and physics don't apply to you? Just to recap- THIS is the argument for why that meter is suitable for high voltage work? Because people change light bulbs? Cooooool. |
| joeqsmith:
--- Quote from: Someone on April 27, 2023, 10:00:25 pm --- --- Quote from: joeqsmith on April 27, 2023, 01:53:22 pm --- --- Quote from: Someone on April 27, 2023, 01:23:16 am --- --- Quote from: joeqsmith on April 27, 2023, 12:39:49 am ---My home has a tiny little service coming into with a small distribution transformer. Nothing like the feeds for the buildings where I worked. Outlets at my house are several feet from the main feed and are behind small CBs which is behind another small one. Worse thing that will happen if I pull and outlet and short the wires, I blow a breaker. Hardly CAT III or risk of an arc flash. --- End quote --- So what's the supply impedance at those socket outlets? --- End quote --- I'll try and make a few measurements today with my tiny home wires. I assume you will do the same so we have something to compare. If not, I can measure some larger circuits. ... I assume because we are talking commercial vs industrial, you want to keep this below 250V? Are you wanting any other metrics or just the impedance for the three legs? --- End quote --- I'm out of that work these days so don't have the instrumentation to hand. It would be very interesting to see just how high impedance can get on your "wimpy" installation. (over here the target end to end is less than 5% droop so there is an upper ceiling). But as this keeps coming back to the same point, it will be possible to find all sorts of installations that will have prospective fault currents and robust voltage filtering/complex impedances that they could well be safely measured with a lower category meter. That is entirely expected since the standards have to cover worst case installations. The "argument" is back to front, if people want to claim the category ratings are excessively strict then it is on them to show every installation meets their new criteria, on the other side I only need to show/find a single example at the limits to demonstrate they are sensible (quickly shown by the current capacity of residential feeds and GPO circuits with their associated maximum droop). --- End quote --- Home lab is two floors away and diagonally opposite of the feed. Testing my distribution block at 20A, the drop is about 11.2%. ASCC is about 0.25kA line to neutral. As I said wimpy and hardly anything that concerns me. *** If I skip the AC strip I normally use and go directly to one of the outlets I measure a voltage drop of 6.3% at 12A. Hot is 0.38 ohms, neutral 0.20 ohms and ground is 0.04 ohms. ASCC is 0.26kA. Scary stuff. *** I have an outlet I use for my small MIG welder that on the same floor and much closer to the feed point. 4.5% drop at 12A. 7.3% at 20A. Hot is 0.31 ohms, neutral is 0.1 ohms and ground is 0.04 ohms. ASCC for this outlet measures 0.39kA. The house has mostly tiny little 14AWG wire. With all the concern I am guessing Australia uses 0000 AWG to wire their homes. *** Tried an outlet at work for the fun of it ASCC was 1.96kA. A little better but still hardly a concern. We don't have arc flash signs on every outlet. Maybe that's code in Australia for all residential outlets. I have been at factories that had to plan ahead with the power company before switching loads. It's a different world than my home. |
| joeqsmith:
--- Quote from: David Aurora on April 27, 2023, 10:57:08 pm --- --- Quote from: Fungus on April 27, 2023, 04:32:15 pm --- --- Quote from: David Aurora on April 27, 2023, 03:27:59 pm ---I turn the switch off before changing them, because I'm not a fucking idiot. To each their own though I guess :-// --- End quote --- What if it's a two (or three) way switch and you don't know if it's on or off? Do you rewire your house first? --- End quote --- If it was really a safety concern (which it's not, but I'll play along and pretend we're talking about a broken bulb where you need to grab the base or something) I'd flip the breaker or grab a chicken stick. I'm guessing this is the bit where you remind us you're a hero and you'd do it with your teeth because you're super tough and cool and physics don't apply to you? Just to recap- THIS is the argument for why that meter is suitable for high voltage work? Because people change light bulbs? Cooooool. --- End quote --- I just screw in the new one with it live. Then again, with these new LEDs, it's rare. |
| David Aurora:
--- Quote from: joeqsmith on April 27, 2023, 11:04:20 pm --- --- Quote from: David Aurora on April 27, 2023, 10:57:08 pm --- --- Quote from: Fungus on April 27, 2023, 04:32:15 pm --- --- Quote from: David Aurora on April 27, 2023, 03:27:59 pm ---I turn the switch off before changing them, because I'm not a fucking idiot. To each their own though I guess :-// --- End quote --- What if it's a two (or three) way switch and you don't know if it's on or off? Do you rewire your house first? --- End quote --- If it was really a safety concern (which it's not, but I'll play along and pretend we're talking about a broken bulb where you need to grab the base or something) I'd flip the breaker or grab a chicken stick. I'm guessing this is the bit where you remind us you're a hero and you'd do it with your teeth because you're super tough and cool and physics don't apply to you? Just to recap- THIS is the argument for why that meter is suitable for high voltage work? Because people change light bulbs? Cooooool. --- End quote --- I just screw in the new one with it live. Then again, with these new LEDs, it's rare. --- End quote --- Yeah, anyone with half a brain can replace a bulb without killing themselves, I was just indulging their point by trying to find a situation where it might actually be a problem :-// |
| Someone:
--- Quote from: joeqsmith on April 27, 2023, 11:02:33 pm ---If I skip the AC strip I normally use and go directly to one of the outlets I measure a voltage drop of 6.3% at 12A. Hot is 0.38 ohms, neutral 0.20 ohms and ground is 0.04 ohms. ASCC is 0.26kA. Scary stuff. *** Tried an outlet at work for the fun of it ASCC was 1.96kA. A little better but still hardly a concern. We don't have arc flash signs on every outlet. Maybe that's code in Australia for all residential outlets. --- End quote --- :-+ >1kA is fairly common here on residential GPOs but it's kept simple so there are no special warnings or differentiation, people treat all outlets as equivalently dangerous (just like 61010). Would I measure any of those examples with a meter containing unbranded/unknown 20x5mm fuses? nope. |
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