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And as long as the electricity doesn't want to go into you more than it wants to continue down the rest of the cable, you're good, right?
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# ? Aug 23, 2017 20:48 |
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# ? May 9, 2024 23:05 |
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Zemyla posted:And as long as the electricity doesn't want to go into you more than it wants to continue down the rest of the cable, you're good, right?
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# ? Aug 23, 2017 21:02 |
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Zemyla posted:And as long as the electricity doesn't want to go into you more than it wants to continue down the rest of the cable, you're good, right? So I'm thinking what's throwing people off about this, is that it seems like if you touch the hot cable you will instantly be electrocuted, right? For starters, even if you were bare footed, the dirt you're standing on has a really high resistance back to the source. Actually, you could peel the insulation off the wire and in almost all cases let it sit on the ground, it's not going to do anything. There was a video where a guy drove an 8' ground rod and hooked a 120v wire to it. Didn't trip the breaker, read 0 amps with a clamp on. That's not all situations, I'm just trying to illustrate that the ground you're standing on is not a good conductor, especially for 120v. The thieves probably just wear regular clean leather gloves, but they may use some kind of rubber gloves as well, and are wearing rubber soled shoes. That's a lot of resistance to 120v. The bigger hazard is between the two legs and neutral - now that has the potential to create a large arc flash, or electrocute you if you got in between them. So simply enough, they only work on one at a time, re-insulating before starting on the next one. Now, I'm just trying to explain how the thieves were able to easily splice into hot cable. As far as I'm aware, no utility would do this, if for no other reason than not wanting to bury a termination. Sometimes we have damaged cable that has to be dug up, repaired, and re-buried...but that is done de-energized and not to splice on with more cable in any case. Anything like that would happen in a vault so it could be accessed. angryrobots fucked around with this message at 23:34 on Aug 23, 2017 |
# ? Aug 23, 2017 21:32 |
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Some contractors found this fine piece of work the other day.
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# ? Aug 24, 2017 23:44 |
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SeaBass posted:Some contractors found this fine piece of work the other day. 480?
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# ? Aug 24, 2017 23:55 |
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SeaBass posted:Some contractors found this fine piece of work the other day. What's going on there? Bad splicing? Weird holes in the enclosure?
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# ? Aug 25, 2017 00:11 |
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SeaBass posted:Some contractors found this fine piece of work the other day. This looks alarmingly like some big-rear end splices from large conductor 3 phase 480 to a bunch of smaller conductors. Are there bugs in there?
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# ? Aug 25, 2017 02:03 |
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Looks to me like the contractor ran short on the larger conductor and spliced on several smaller conductors to finish the run.
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# ? Aug 25, 2017 02:22 |
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Noctone posted:Looks to me like the contractor ran short on the larger conductor and spliced on several smaller conductors to finish the run. That's our working theory right now. They're tracing it out but we find stuff like this about once a week.
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# ? Aug 25, 2017 02:45 |
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I got asked a couple of questions last night about a situation that a friend of the family was having in regards to their business and their local electrical inspector who came by as they were finishing up replacing the lights in their new office space. The company builds highly specialised scientific gear ($1-10mil devices), which requires obviously very specialised electrical gear. Evidently the inspector came, and all the standard work they did (lighting - they replaced florescent lighting with led because the ballasts gave off too much electrical noise) and that part was fine. Then the inspector saw the scientific gear and went nuts. Demanded things like replacing AC/DC inverters (<.0001% noise) with "industry standard" ones (~10% noise), wire coils that do EM/gravitational counter measures must be encased in steel conduit (making them completely useless) and fun things like that. And then left when he starting arguing with the dozen or so (accredited) engineers on site without signing off on the work permit (ie: lighting change) - so there's now a lovely impasse happening. Also, the inspector is actually an outsourced agency from the municipality, so every time they (try to) talk to them, they get a bill for like $500. Anyone run into stuff like that and have any advice I can pass on? (The company is based out of Ontario/Canada.) The only thing I could come up with was to get the scientific gear to be "out of scope" to the inspector so he couldn't comment on it. Is it possible that the electrical engineers on site can do sign offs?
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# ? Oct 24, 2017 19:18 |
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I was looking at a substation and noticed that the area under their VRLA batteries looked, uh, worse for the wear. There are 92 batteries, and they're all pretty new (oldest are about a year old, youngest are 6 months). Is this just old acid scars? It looked like a little bit of liquid there, but I couldn't find any obvious leaks. No corroding at the terminals. It looks like poo poo but I'm not sure it's actually a risk going forward (just something that stripped paint in the past). Basically I think the health of the batteries looks good and the scarred floor is just cosmetic and unrelated to the current system setup. Does that seem like a sensible opinion to take or am I missing something? I am not very experienced with battery systems, and most of my concern is that the batteries will actually produce amps if needed. Pander fucked around with this message at 19:38 on Oct 24, 2017 |
# ? Oct 24, 2017 19:36 |
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Pander posted:No corroding at the terminals. Uhhhh looks like there's a fuckton of it.
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# ? Oct 24, 2017 19:44 |
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Looks like from an old battery setup that has been replaced - you can see the old floor brackets screw down points, and I think that's a shadow on the wall of the old setup in the first picture. Edit: Yeah, terminals aren't looking great.
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# ? Oct 24, 2017 19:46 |
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Either way if you're not doing a PM on those at least once a year then you're loving up. It's incredible how many places we go to where the customer's batteries may as well be paper weights.
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# ? Oct 24, 2017 19:47 |
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Noctone posted:Uhhhh looks like there's a fuckton of it. I thought it was just lubricant or something. It didn't seem like corrosion from these newer batteries. There's no way the floor could be that hosed up from batteries under a year old that aren't bleeding acids in a super obvious manner, is there?
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# ? Oct 24, 2017 19:52 |
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I mean I guess yeah that could be grease, although if it is then whoever put it on went waaaaaaaay overboard.
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# ? Oct 24, 2017 19:58 |
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Noctone posted:I mean I guess yeah that could be grease, although if it is then whoever put it on went waaaaaaaay overboard. Yeah that's my guess. I'm just gonna recommend the client actually perform PMs on the batteries unlike previous sets. And also MOVE THEM. Behind where the photos are taken, about 5' from the batteries, are the switchgear CB/relay cabinets, an entire wall of 12.47kV CB/relays. An arc flash from one of those cabinets could likely engulf the batteries which strikes me as suboptimal. I'm used to seeing batteries in their own room with dedicated ventilation, so I'm pretty sure that's a NEC/IEEE violation of some sort.
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# ? Oct 24, 2017 20:07 |
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I think it’s grease.
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# ? Oct 24, 2017 20:08 |
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Oh poo poo really? lmao, I don't know if it's a code violation but the only places I've not seen batteries in a separate room are oil & gas PDCs.
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# ? Oct 24, 2017 20:10 |
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unknown posted:I got asked a couple of questions last night about a situation that a friend of the family was having in regards to their business and their local electrical inspector who came by as they were finishing up replacing the lights in their new office space. The company builds highly specialised scientific gear ($1-10mil devices), which requires obviously very specialised electrical gear. Make a loving lot of noise with the elected officials about moving to a J with a different AHJ E: Maybe things are different in Canada but here in the states industrial machinery is covered by an entirely seperate codebook, NFPA 79, and you either demonstrate a safety management program and engineering capability to participate in a self-certification program, or point to a UL / TÜV / other NRTL certification sticker on the equipment and tell the inspector to gently caress off shame on an IGA fucked around with this message at 20:49 on Oct 24, 2017 |
# ? Oct 24, 2017 20:30 |
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Noctone posted:Oh poo poo really? lmao, I don't know if it's a code violation but the only places I've not seen batteries in a separate room are oil & gas PDCs. I'm not sure. The specific code I deal with (UFC 3-520-05) points to NFPA-1, and in NFPA the closest I can find is basically "make sure it's got a 1 hour barrier from the rest of the bldg" (52.3.3.3) which is perhaps N/A since it's just a metalclad trailer and "battery systems shall be housed in a noncombustible, locked cabinet or other enclosure to prevent access by unauthorized personnel" (52.3.3.2) which seems more worried about personnel access than separation from potential sources of ignition. It SEEMS bad to me but maybe there's no specific code violations? The UFC definitely has an applicable paragraph: code:
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# ? Oct 24, 2017 20:56 |
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Pander posted:There are other installation codes I'll check out like IEEE 484. So far the gist I'm getting is "there's nothing specific saying not to install these near potential high-energy arc flash hazards but boy engineering judgment suggests it's a bad idea". I have seen drawings with batteries in a separate room, but everyone building I've designed (data centers, wind farms, and solar plants) or visited (utilities, universities, and wind farms by other designers) had the batteries in the same room as the relay panels and switchgear, where applicable (only a few sites had indoor switchgear). Usually a fan is set to run every hour or so to vent potential build up of hydrogen, and there may be a hydrogen detector to send an alarm to SCADA. Fake edit: I worked in a high-power short circuit lab where the battery system was in it's own room. That's the only time that I have personally seen it.
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# ? Oct 24, 2017 22:16 |
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shame on an IGA posted:Make a loving lot of noise with the elected officials about moving to a J with a different AHJ I'm sure that's basically what will happen ("this isn't your jurisdiction so gently caress off") it just caught them by surprise a couple of days ago and is they weren't expecting to have to go down that route and were trying to resolve it amicably.
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# ? Oct 24, 2017 22:57 |
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Our battery bank is in the same PDC as our 4160 switchgear - about 5 feet from it. This is in a brand new facility, too. Also, gently caress lazy people, I tell all our guys after they are done diagnosing and treating a problem, get rid of the old rust/arc marks/ etc: so some poor soul isn't in that same position of trying to figure out if it was existing or not. We wouldn't tolerate someone installing a new battery bank over that.
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# ? Oct 25, 2017 01:03 |
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# ? May 9, 2024 23:05 |
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Just rediscovered this thread after like 3 years of not looking at it. The PE exam is in 2 days. Studying for it made it so I can actually understand most of this thread now.
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# ? Oct 25, 2017 20:15 |