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Admin
TRWTF is trusting the automated outages voice
And TRRWTF is the fact that a space heater can overload the entire building's circuit!
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I'd hope the reason behind that would be more of the "space heaters are a fire hazard" than "space heaters overload the entire building"
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"Don't get a heater, tell us the airco is set too low"
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You joke, that was in the Monthly Newsletter published a week later!
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My experience is that, usually, the hotter it is outside, the colder it is inside. I have worked places where I literally wore a parka at my desk.
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It could have triggered the ground fault interrupter if it was faulty - in which case the guy bringing it in shouldn't be allowed anywhere near to an electrical outlet.
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Additionally a large number of space heaters, each putting a load on individual circuits, but not enough to trip can aggregate to enough current to trip an upstream (possibly even building main).
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Tell me about it. I went to GenCon this year (end of July, beginning of August) and had to wear a sweater in the Convention Center.
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I came into work late one day, turned on my PC and everybody's PC died. Not the lights or most of the monitors. A quick check of which extension leads where plugged into which other extension leads turned up a fan-heater plugged into the UPS protected circuit reserved for PCs. The in-rush current on my PC was enough extra load to trip the breaker on that circuit.
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The heathens I was with insisted on using the outdoor sidewalks on our 4x daily slogs to the opposite end of the world (we really fucked up scheduling) instead of adding fifty feet and getting into the goddamn air conditioning.
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I use 'keyed' plugs and sockets for our clean power. This was after someone plugged a visual inspection machine into the clean feed and bombarded me with over-current emails from the UPS.
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No kidding! Powered by Three Stooges.
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there is no such thing as too cold. 0K, maybe a bit cold but hey.. put a sweater on.. :smile:
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That right there is TRWTF. If you're not developing on a battery backup--either on a laptop or a desktop with a UPS--you're Doing It Wrong. They're not just for servers.
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Belatedly, this story reminds me of an event during my college years, that I shall call "Power Trip - The Radio Station".
My roommate had an FCC license that allowed him to be engineer of the college radio station. As a result, I spent a fair amount of time in the radio station; visiting, whatever.
At the time of the story, the radio station was undergoing renovation. The walls in the lobby area were stripped, the electrical panel was open, and there was an aluminum ladder standing in the middle of the room.
While horsing around, a couple of other guys managed to knock over the ladder. Which fell, as if on guides, so that the top step directly and exactly bridged the three phase input terminals to the power panel. Need I mention that aluminum is conductive?
There was an intense flash...and then blackness. This was the days of vinyl, so we were treated to the diminishing sound of musi c s l o w ... i ... n ... g down before the console capacitors were exhausted and silence reigned.
This condition is called "dead air".
(Tripped the main breakers for the building.)
Admin
You were actually quite lucky that those guys didn't touch the ladder when it landed.
Had they tried to prevent it from falling they could have been electrocuted (no kidding!) depending on which way the current decided to go.
Even American 120 V is is plenty enough to kill.
An other item is: why were the 3-phase panel even accessible to to the ladder with power on? (I know that that would not be in accordance with European work environment guidelines / laws)..
Yazeran
Admin
The problem is he should have called an electrician the first time it happened instead of trying to troubleshoot it himself.
There's a problem with their building's circuit breaker's selective coordination. Coordination is the synchronization of the time delays and trip levels in circuit breakers so that the downstream breakers trip before the upstream ones.
Particularly large or mission critical systems use a system called zone-selective interlocking. A downstream breaker detects a fault and sends a signal to the upstream breaker that it's going to trip and to hold off for a little while longer.
This is important when you have a dead short like the heater did. You do that with either breakers with electronic trip units or replaceable sensor plugs, and it's often difficult enough that the electrical contractor has to send out to a consulting company which provides a plan.
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As @TheCPUWizard mentioned, it may be the case that no individual branch was overloaded, but the sum of the almost-fully-loaded branches was too much for the main. Since no branch was actually overloaded, there was no downstream breaker about to trip.
Say what? The heater may have been a heavy load, but nobody claimed it was a dead short, and I very strongly doubt that it was. This, however, is quite true.Admin
TRWTF is the lack of any actual IT angle. I saw an electrician around here the other day... wait a minute. Has it happened? You're all electricians aren't you (stumbles out of and over own chair and scrabbles backward)...
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Unfortunately in small companies you often get the boss yelling, "your the expert that's why I hired you. Get it fixed now"
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No, it's impossible to be a simple overload. Circuit breakers have time-current response curves so that they match the heating of the wiring. The primary purpose of a circuit breaker is to protect the wiring from overheating. So, small overloads will take minutes to trip.
Looking at a typical curve for a medium sized breaker, it says that a 1.15x overload (the minimum it should trip at), it should not trip at anything under 30 seconds to 300 seconds, depending on the sensitivity setting. In order for a trip to occur in 10 seconds, it has to be an overload from 2-9x rated current.
So you can see, a simple heater, which is 10 amps or so, is not going to repeatedly and instantaneously trip a 500 amp++ main breaker. Even for a 100 amp home breaker, it can only cause a 10% overload, which will take minutes to trip. If the system was really overloaded to the edge, they should get random trips throughout the day as things like copy machines get used.
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That is really weird, it shouldn't happen quite that way. The main breaker would have to have been right near its trip point, and that way for a long time, as to have heated up internally, while the individual office breaker must have been very lightly loaded, before the heater was plugged in. Possible, I guess, but very rare.
I've seen the opposite situation, whgere the steam valves on the radiators were so corroded, in the middle of winter the room was so hot, people would turn on the AC, and the AC coils would freeze over, and Building Services would get called in to fix the AC, in January.
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The building folks eventually fixed it, but we had to move out temporarily for asbestos abatement.
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Or use auto-save.
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TDWTF really stands for The Daily Watts, Teslas and Faradays.
Yes, yes, Discourse, this is similar to what I recently posted because I hit the reply button on the wrong post for that … This is the post to correct that slip-up, damn you.
Admin
Yeah, that wasn't the brightest thing to have done...leaving the panel open in an area where non-electrical workers were walking...especially overnight. Hindsight...!
I'm not done! Discourse!
Admin
TRWTF#1: Offices that are refrigerated to the point of needing a jacket in the summer. I work in one, and I feel like Mr. Rogers when I walk in from a beautiful day in the neighborhood and have to put on my sweater.
TRWTF#2: A space heater can easily trip the breaker for an individual circuit, but the whole building? Something ain't right with the story.
TRWTF#3: Mike notices the power goes out after he plugs in the heater. So he does it again, and again, and still fails to see the connection?
TRWTF#4: Being on an important call with a customer and using Twitter are not mutually exclusive. Jeez, have you ever been on an "important" customer call? Two dozen people conferenced together, so your C-level management and their C-level management can try to out-bluster each other rather than trying to actually fix what's wrong.
Admin
Eh, why? Power goes out, you get the power back on, restart the computer, open up Sublime, and continue working. What have you lost but some time?
Admin
It can happen, for a short.
The same roommate as in my earlier message was working on a piece of station equipment. It had standard headphone-type plugs on the chassis, and he had just been using one of them to tune it. There was another one there that was unlabeled and he decided to plug his headphones in to see what that signal was.
It was fortunate he was wearing the headphones around his neck and not on his ears because, as he quickly learned, that jack was connected across the 120 V line. (He said fire shot out of every crack and hole in the chassis when he plugged in.)
Anyway, that blew the breaker for the whole sub-panel he was on, not just for the one circuit. So it can happen, even for "ordinary" shorts.
But I get the impression from the article that it wasn't a short, it was just the extra load. Even assuming inrush, an extra hundred amps shouldn't blow the building breaker--unless someone took a few serious shortcuts in load planning.
So, ummmm, what happens if they need to add a few more servers? Right.
Some people are cause and effect challenged.
Admin
Another facilities related comment: the common way large buildings handle air conditioning is with a reheat system: the air is cooled to meet the needs of the hottest part of the building then heated back up again (either using a separate hot air duct or a hot water or electric heating coil) in the rooms that need less cooling. So in many cases, it saves energy to leave the air cold than to spend more energy heating it up again. (Newer buildings have variants of this system which can be more efficient)
It's also why if you put a data center or simple server closet in your building without it's own air conditioning system, you can cause your energy consumption to go through the roof.
Admin
I'd rather have daily Fridays, preferably with doughnuts, like a former employer had.
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N=1 isn't statistically significant...
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I've seen a small overload (10's of amps) trip a 100A type-B MCB on a distribution-panel instantly. I went to the local electrical supplier to get a type-C as it was UPS inrush and was told MCBs can age and that's not unusual. Replaced it with a brand new 100A type-B and everything was fine.
Admin
So every day is a Friday?
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Fridays were good when I was working there. In addition to the usual end-of-the-work-week goodness, every Friday was either doughnut Friday :yum: or the day after payday, so I actually had money to buy food, pay rent, and the like — occasionally, but rarely, due to doughnut scheduling irregularities, both.
Admin
+1. LOL'd, would read again. Typical here in America. In summer I bring a jacket to restaurants so I don't freeze while waiting for my meal, for example.
FTFY
I've seen (usually older) buildings with grounding issues that cause all kinds of weird problems.
+1. You can't fix Stupid.
Not sure if this is worth a 'someone didn't get the joke' flag. I inferred from the article that the person making the important call claim was likely not on a call at all but instead was really on Twitter or some such time-wasting activity. TRWTF™ is Twitter-boy was simply using the opportunity to be toxic (I avoid such people as much as possible).
Admin
This.
Apparently there are still programs that don't, you know, make any effort at all to keep you from losing all your hard work, though. For some reason.
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I assume earth==ground in this context? Never heard 'earthed' used in an electrical context before...
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It's a wrong-side-of-the-pond English thing.
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My Xbox is on a UPS.
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Ah. I figured it was either that or something lost in the translation (if he's not a native English speaker)
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Õ.o
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What? ;)
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Oh nothing. Just that... Well..... Never mind....
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Priorities, man! :)
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Could be that, too. I think, for example, German uses Erde, and I suspect other languages use the equivalent of earth, but I don't know if they they verb it (i.e., earthed).
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:wave:
On both counts.