A thing may be technically correct, but for the health and safety of the public at large we need to adhere to a consistent policy with what we say in the public sphere.
Mains voltage is dangerous and kills kills kills. Never connect anything to the mains power supply unless you are licensed to do so, or employ someone who is licensed to do so. Always assume a circuit is live unless you-personally have checked and locked out the breaker with your own personal lockout device that only you have the key to.
I'm being silly, but you are going on about how the wording of statements matters.
Pointing out "problems with the phrasing" doesn't make for very substantive discussions. Also, snark is deprecated here. Please see https://news.ycombinator.com/newsguidelines.html.
Albeit the thread didn't invite substantive discussion on it because of the snark.
And if you plugged in your TV yourself, and they find out, you just unplug it immediately and wait for the licensed union electrician to come plug it in for you again.
- move furniture that didn't have wheels (so no moving of desks, side-tables, or even some of the larger waiting-room-style chairs). We were allowed to install wheels on furniture ourselves and then move it however :)
- hang pictures or anything on the wall (except when using that blue tacky stuff; you'd be surprised what you can hang with massive quantities of tacky)
- plug in a new power-strip, surge-protector, or extension-cord (we quickly learned to get the big 20-outlet strips)
- set up any kind of networking equipment, even if it was air-gapped from the university's network (we violated this all the time)
- plug in anything that drew more than a certain number of amps (an amperage level that was quite close to what many tower desktop computers were drawing at the time; we always just risked that)
Union workers were always prompt and polite when we'd ask them to do these things and they always had a "ya we know it's dumb" attitude about these requests. One time I saw the bill for the services: around $50 to plug in a surge-protector (that we provided) and $100 to nail a framed picture into the wall. The fine for not getting the union to do these jobs was something like 10x the cost of the labor iirc.
On the bright side, at least you know your electricians weren't being exploited :)
Well, actually there's a logical reason why only the union workers were allowed to do the mentioned things (tl;dr: company/university wants to shield themselves from liability):
- move furniture: shield the university from injury claims in case something goes wrong. For example, consider you moving a yuge chair around wearing flip-flops and you accidentally crush your toe during lifting. The university can now deny your claim as you were not supposed to have done this. In the crazy US system with its even crazier damage payouts, I wonder why this isn't commonplace.
- hang stuff on walls: the older the building, the bigger the chance that you'll hit some live wire, a water pipe or whatever is buried in the wall. Plus, again, personal injury claim risk.
- set up networking equipment: all it takes to bring the network to a grinding halt is accidentally connecting that router you planned to use for playing Counterstrike to the university network and whoops, where's that extra DHCP daemon coming from?
- amperage limit for devices: older circuit breakers tend to get a bit... trigger happy with age. Which means what will work fine now may be too much (especially surge) load in a couple of years and these issues are tricky to debug. In addition, I have seen a wild variation of power cables and extension cords when it comes to their current capacity (e.g. there exist power cords with 3x 0.75mm2 wire, these are rated for 2.5A tops aka something around 550W - but what if the component uses 800W?). Having someone trained look at all involved components before plugging them in can and will prevent fires. Not only to check if they're safe from an amperage limit, but also to check if their isolation is broken, there are scarred areas from arcing, ...
RE the wall they also said that nails and tape were also damaging to the paint (and repainting the walls was another union's thing), so the wall-hanging guy would have to log the "damage" to the wall caused by the hung item, presumably for cost/accounting purposes when it came time to repaint the wall.
That CYA stuff is actually typical for any company that ever gets hit with a personal injury or other expensive lawsuit. It's pervasive in government/bigco's because they had to deal with decades of every imaginable stuff happening.
If you want to get rid of it, you gotta limit personal injury liability (which would border on being inhumane) or develop a decent social safety net with proper insurances...
This is important: big orgs—government and private—not only have more chance of having an incident (because they deal with more events because of their scale), they are often bigger litigation targets when an event occurs, because they are giant bags of money.
There are plenty of people that don't understand(and probably don't want to understand) how things are connected. I doubt they think that the light switch magically turns on the light, or that the water magically comes from the valve attached to the wall, but the method, or desire to know the method, in which those things happen is just not in their world.
Nope. There's a type of wire called "Stegleitung", essentially a flat cable. Often enough it's simply nailed into the wall, then a thin coat of mortar is applied on the wall, and then paint.
Source: zapped myself once by hitting such a cable.
In addition, the usual injury liability is a problem.
Distrust—usually well earned—of management is the main way. The incidental items that are mocked are not the issue, the issue is that without an inflexible blanket rule, management will bend any other rule to use people in nominally different job duties to replace union labor.
Also, sometimes, the rules are negotiated in part by unions other than those doing the work, to prevent their covered staff from being compelled to do other kinds of work (and selected against for inability to do so: if lifting heavy items is part of the job duties of, say, someone in a clerical union, then inability to do that well can be used as a hiring, promotional, or termination consideration for such an employee.)
Even in places (as sometimes happens) where orgabized labor and management have good day-to-day relations, there usually is a feeling—with good historical reasons behind it—that the foundation of that good relationship is a “good fences make good neighbors” style solid set of baseline rules around which, where it is important (and the little stuff that is fun to mock isn't that) negotiated exceptions can be made.
"Do not rest your tongue on the plug as you insert it into the wall."
I get that electricity is dangerous, but are there really functioning adults hired by a company that can't be trusted to plug in a simple appliance without a safety briefing first? It seems insulting to their intelligence. Or do they make everybody do this so the one or two absolute morons don't feel bad about being forced to take the "completely basic life skills" course before they're allowed to function at even a very low adult level?
Yes, it’s meant to say something like us unlicensed folk aren’t permitted to hardwire anything to the mains supply.
In Australia you’re not even supposed to replace an existing power point outlet thingo unlicensed. If course, the hardware stores sell them, and we do. But there ya go.
In fact you're not allowed to install any fixed wiring without an electrical license. It's ridiculous - technically you aren't even allowed to install Ethernet outlets in your own house because it counts as "fixed wiring". Other trades have just as bad a grip on legislature, you're technically not allowed to replace your own tap seals either.
> Of course, the hardware stores sell them, and we do. But there ya go.
Of course, in theory there's no difference between theory and practice... ;)
In Victoria for example, you're not allowed to do any work on your own home if it exceeds a certain monetary value without first running through a Kafkaesque bureaucratic process to obtain a certificate.
This doesn't sound unreasonable until you realize that they don't care if you have any qualifications related to the work and don't even want to know what the work is. They simply want to confirm that you haven't done any other work (on your own property) in the last five years.
If you have, sorry, need to hire a registered builder. This prevents anyone from legally buying a home, renovating, and selling it, or even doing any significant work on your own property more than once in five years.
And if you want any other tradesperson to come to assist for anything while your doing it (installing a power point for example), then you need in person occupational health and safety training at a "registered training institute".
You only need to apply to be an owner-builder if you are doing your own work instead of hiring someone who is already permitted to do the work. This is no different from the US practice of having licensed contractors/electricians carrying out (or signing off on) large projects.
You only need to apply to be an owner-builder if you are doing your own work instead of hiring someone who is already permitted to do the work.
That is precisely what we are discussing. The restrictions on doing work on your own house yourself.
And this applies to any work at at, not just work that requires licensing (plumbing, electrical etc.). Even if you're doing the overall work yourself as an owner builder, you still need to hire licensed professionals for those tasks.
So the difference between "electrician installed" and "mysterious, unknown person installed" is only in the finished product.
I'm not an electrician so correct me if I'm wrong, but for those unfamiliar with residential wiring in US homes, ordinarily homes are supplied with two out of phase 110VAC lines. Heavy appliances like electric clothes driers and electric car charging points use the 220VAC that I available between the two "hot" lines. Everything else in the house use either one of the "hot" lines (black wires according to the national electrical code). There are actually 3 wires going to each outlet, light, etc. though the house: one black (belonging to one of the two sources of 110VAC), one white (called the neutral line, approximately 0V above ground, and one green a separate green wire that is connected to ground around the point where power enters the house.
Fundamentally, the power grid is based on three phase power. Typically, the average telephone pole will have four power wires on it, and one or two thick bundles of phone line or maybe cable TV, I dunno. Three of those four power lines are the three phase electricity, and the fourth is the common neutral line that is ideally near 0V, but typically fluctuates a bit.
Only three out of those four lines enter your house. One is is the neutral line, the other two are just two of the three power lines. Those two power lines are not 180 degrees out of phase, they are 120 degrees out of phase. If they were 180 degrees out of phase, the math is simple: it's obviously just 240V. Since it's 120 degrees out of phase, you end up with a sine wave that looks something like 120\(sin(x)-sin(x+pi\2/3)). (only you need to adjust it for frequency) If you're better at your trig identities than I am, you can calculate that out exactly, but for simpletons like me I just plug it into my calculator and find a local maximum of 207.846 something.
(note: In the US, we use neutral and ground to refer to the common center of the three phase power, and the wire that is buried in the ground near your house, respectively. In the UK, I think they call these two wires ground and earth, respectively. Note that the term "ground" has a very different meaning (read: one of them can kill you, the other one keeps you safe) depending on the context.)
Two of the phases DO NOT run to the house, a typical US household service is split-phase. The primary winding in the transformer at the pole connects between a single phase and ground, and the secondary winding is center-tapped to provide a 'neutral', with 120v on either side of the neutral. The voltages are indeed 180 degrees out of phase.
Your test would show 220-240v in the vast majority of US-based residential situations.
The 120/208 you are referring to is when all 3 phases are fed in to a WYE transformer that has 3 120v secodary windings fed from a center point, which becomes the neutral. With a WYE transformer, each phase gets 120v to ground/neutral, and the phase-to-phase voltage indeed peaks at 208v due to the 120 degree rotation between phases. This is typically only found in large residential(600+ amps), and medium to large commercial and industrial buildings with 3-phase service.
Another method would be using a 'Delta' transformer, in which one of the phase-to-phase windings are center-tapped, similar but a little different than the single-phase residential service. The two phases on either side of that center-tap will be 120v to neutral, but the 3rd phase will be 208v to netural/ground. This is usually called the 'wild' leg and is often used to power lighting loads.
Source: I've been doing this for a long time.
Also https://www.doityourself.com/forum/electrical-ac-dc/549775-l...
And https://ctlsys.com/support/electrical_service_types_and_volt...
The few houses that I was involved in wiring of in the states were definitely "split phase" systems, which work like the GP describes. In those, three current-carrying wires come from the transformer - two ends and a centre tap from one winding. Those are wired in the breaker box so that the house has two circuits that are 180* off from each other, giving 110V on either circuit, or 220V between the two "hot" legs. There's a better description at https://en.wikipedia.org/wiki/Split-phase_electric_power.
The current for the same wattage will be roughly double in North America. So lamps, etc. intended for use in Europe will have wiring that is undersized for the current draw if used in North America.
We found exactly that, lamp cords and extension cords, when we started our remodel a month ago. The former owner did some renovation ten years ago, and was an architect so we always assumed he did a decent job. That was one of a few questionable choices he made, so we're now re-wiring the entire house.
An organisation called TechSafe[1] is charged with carrying out random inspections.
Everything thinks they're smart, they can do things safely, etc., while only for a much smaller subset of people is that true.
Generally, playing with voltages above 50V is something that should be done with care and a professional/adult present.
Why should everybody have to pay a continuing overhead simply so people with small children don't have to install outlet covers?
If you're actually concerned with electrical safety, you're much better off installing solid "commercial-grade" receptacles than pretending that garbage-grade ("residential") has been rendered safe by being more difficult to use.
[1] https://ae01.alicdn.com/kf/HTB1Cya9KVXXXXXoXpXXq6xXFXXXK/202...
Here in the US we did change our plugs, by introducing polarized plugs. We don't have to be change-averse.
I still occasionally see an old switchboard with ceramic wire fuses with the fuse wire replaced with a bit of coat hanger wire, or the correct fuse wire wrapped around the terminals ten times. They often seem to be the same houses that give you a tingle if you touch any of the metal plumbing fixtures. Yikes.
Hardware store still carry traditional outlets as well.
The issue is exposed live voltage when you plug it in. Schuko and Europlugs generally don't allow this (even the flat plug is designed such that the contact aren't exposed anymore when they make contact)
Any time I see them working directly on high-voltage lines, they connect a device that looks like jumper cables in-between the phase(s) and ground. They also put bright orange flags on this device so that it is easily visible to anyone nearby. It seems to be a great practice and seems to make things nearly fool-proof because this effectively shorts out any power that may occur on those lines.
I don't think I've ever seen a lineman work on a power line in a manner that would cause him to be electrocuted if surprise power were to occur on the line. I'd bet it's in policies and procedures somewhere, possibly even in OSHA requirements.
The requirement of not backfeeding is another layer in this multi-layer protection scheme.
If a system is successfully backfeeding the grid, something is badly wrong. If a linemen is then electrocuted by this backfeed, something is almost impossibly wrong.
It's unreasonable to assume that a lineman can identify which sections of a downed line are isolated before they get to work repairing the power lines. There are circumstances where the line might even be isolated without being physically disconnected because a fuse blew downstream of where the line was grounded before the lines actually came down. Fuses will have a visual indication that they are blown but it's just a pin that sticks out the bottom and it's easy to miss when you think the only problem is a downed power line. There's an army of fools who know just enough to be dangerous and it's easy to see this on YouTube. Here's a great example of what linemen have to worry about when repairing downed lines.
https://www.youtube.com/watch?v=KiByz1E4IBU
Wouldn't you be worried working with downed lines not knowing if that guy just so happened to live across the street?
Not doing so is putting an awful lot of trust into a potentially large number of people that you've never even met.
Because you just don't know what some idiot has done...like the guy in the video.
That completely changed my perspective on all those quite lines dancing in the wind.
I cannot think of a time that I saw a lineman working on a power line that was not shorted, without protective gear.
Working on a hot wire is a whole different story because every thing around you becomes a hazard.
I do work on towers, sometimes in hot-RF environments (TV and radio antennas transmit with up to ~100,000 watts). The antennas will literally cook(like a microwave oven does) you if you get too close while they are live. For lower power situations, you can even hold your hand near the antenna -- it feels like a heat-lamp. Even at reduced levels, it can be harmful to areas of your body with poor circulation and cooling(such as your eyes), often causing damage before you're even aware of it. We wear an RF monitor when in those situations that alerts us if the RF field becomes stronger than is safe. I wonder if linemen wear a similar device that can alert them if an EM field becomes stronger than expected?
If I worked on wires where I was not in control of incoming power, then I can not be sure the wire isn’t hot just because I measured once. This is for example the case when working with stuff with big capacitors.
So my point is: can line workers really assume a wire isn’t hot just because they tested it? They don’t control both ends, since as you pointed out, anyone could have a) a power source or b) a faulty connection, whether it’s allowed or not. So as a line worker I’d basically just not touch anything even in supposedly dead grid sections.
Used on electrical circuits as well as dangerous machines if you need to climb inside a compactor for maintenance or something.
https://www.osha.gov/Publications/3120.html
http://www.deenergize.com/?target=Universal_Circuit_Breaker_...
Locks on the breaker itself are more rare (usually for low voltage repairs where the common person might frequent the area)
The lineworkers I've seen that aren't working with live wires use a special tool to ground the wires (it's a set of three clamps connected by a thick wire to a grounding rod). Once the wire's grounded, it's going to be hard to put any voltage on it.
The obviously missing third top line is the one that broke. It simply snapped around the middle of the span between that pole and the pole that is outside the photo on the right. They went up in the cherry picker, cut the dangling line, and then put on those clamps.
They then covered the lower arms of the pole with orange sheets: https://i.imgur.com/zZ3DFSd.jpg
Does anyone happen to know what the orange sheets are for? They did not use them anywhere else where they grounded the wires.
The place where they put these orange sheets in your photo looks like a disconnect switch between the wires on either side of the pole. So the wires coming from the left side of your photo are still live, and the disconnect switch itself is still live. Since they would be working near the disconnect switch (to hang the new wire), they put these insulating orange covers for extra protection.
I don’t know if the workers make a habit of physically disconnecting all of the houses that are connected.
For this reason, I'd be most surprised if there's a single backfeed system in existence which doesn't isolate your house from the grid once the grid goes down.
Edit: Finally got around to reading the blog post to the end and found that the author makes this exact point in the paragraph following the one quoted in the comment above.
This is wrong and dangerous. Suddenly energising a section of grid which has been isolated from all known power sources could easily kill someone working on it. Yes, lineworkers will isolate and test lines before touching them. No, this won't protect them because your inverter could start outputting after they've tested. Yes, your inverter will probably overload and trip out before putting too much voltage into your local section of the grid, depending on where it's isolated. No, it's not OK to bet a random stranger's life on it.