Yes … we see very little Ownership & Accountability these days … in any direction you look.
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German law. We had to advance when others caught up, else there would have been a de facto standard 
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Well, afaik you don’t need an earth leakage circuit breaker per room or per circuit. It’s required for bath (damp rooms) and garden (outside the house), it’s recommended for living rooms and sleeping rooms, it’s recommended not to install earth leakage circuit breakers to light-only circuits, though.
It’s recommended not to use one earth leakage circuit breaker for the whole house, but you could (and it’s common way for serial house, as it’s the cheapest way to do it).
There is another quite new rule to use Arc Fault Circuit Interrupters, but that’s only for public buildings, labs and buildings with increased fire hazard.
Just notice the pdf… Seems like the the “could” has become standard somehow. Just as in Germany. Then I spoke to a college of mine who did educated not so long ago… He said there are combi circut breaker/RCCb´s available in Denmark as well, (I have never seen those) from Eaton… But they cost a fortune, like 10 times as much as a normal circut breaker (fuse).
Now wonder why they use words as “could” insted of should 
Yeah, my college told me about that one as well. Thats the next thing coming…
About 10 years ago I had my UK House rewired, and instead of the old loop power to the celin rose for light circuits (i learned as a summer job at 15 in 1980’s) the power was looped into the switch about 2010 look back at the wiring regs this was issue 17 (2008), issue 18 (2018).
In the UK is now getting very difficult to do electircal work on your home part P building regs need all major work (adding a new circuit, rewiring) all work in a wet room (kitchen or Bathroom) have to be reported to Building control. A change to a face plate or light fitting (minor work) can be done around the house since about 2005. So we DIY’s may be invalidating our insurance with out knowing it.
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I just got the forum summary post with this thread listed. It caught my eye and I began to read from the top. It caught my eye because of the use of the term neutral. I may not understand what the OP was referring to with this term.
Having lived in several states, and been journeyman electrician in a past life, and as @rlkoshak and others have noted, code in the US has been line/neutral/ground in new construction, in most states, since the 1960’s. The same for rework of older 2 wire systems or rework of even older knob-n-tube.
So, to clarify, (for residential, 120VAC) the bare copper in in romex is ground (this runs back to the electrical panel and is connected to earth ground), neutral is the return carrier (this runs back to the electrical panel and is connected to the ground buss bar in the panel, and is thus connected to earth ground), line or hot is the high potential (this is run back to the electrical panel and connected through a protection device (fuse, breaker, etc.) to one leg of the 240VAC split phase entering the panel). In the case of BX (Flexible metal conduit) in some cases allow the conduit to be used as the ground. This is also the case for rigid metal conduit.
Except in older cases (typically, where the 3 stoogers did the wiring and not electricians, or knowledgeable layman), I have never found a box with no ground. I have found boxes with no neutral because it was the far end of a 3 way switch for example. So, far I’ve been lucky and found a box with a neutral nearby and could run a pass through between the boxes. (I did rewire a house that had knob-n-tube re-wired in the 1940s/1950s. At that time romex was a two wire affair (one white, one black conductor wrapped with paper and the outer sheath of a asbestos cloth like “stuff” (technical term) 
. In this case the white wire went back to the box and was connected to the ground bus. As the house was refurbed in the 60’s we replaced the electrical panel and the wiring with “modern” 3 wire romex. That was long before there was any glimmer of home automation, so…)
Not sure any of this is relevant other than to ask if I’m misunderstanding the use of the term neutral in this thread… 
BTW, Electroboom has a nice YouTube video on the UK state of affairs (he actually travels to the UK and during his usual antics, blows the breaker on the whole floor of the hotel…and pretends it never happens 
):
https://youtu.be/abqMLqHwqpo
What an idiot! 
Actually, he’s quite an accomplished electrical engineer. Electroboom is his YouTube persona where he actually demonstrates lots of electronics principles by making lots of sparks…and booms. 
Check out the ones where he debunks the guy passing current through his body, or the one where he exposes the automated shower head that is designed with no ground! 
Switch boxes can have no neutral for a couple of scenarios.
- If the main line goes to a light and then a cable is run to a switch, the switch will have the bonded ground but no neutral.
- The other scenario you mentioned can happen in 3-way or 4-way switches.
Exactly. 
Thank you for your feedback. Not sure what else to call neutral but by its official ‘name’. In my current house, and the few switches I wanted to replace with smart ones, there is not always a neutral wire. Also, the wiring (in my current house) is not Romex, it is instead made up of multiple solid copper wires, all encased in metal tubing (conduits). The copper wires come in a multitude of colors … typically black/white for live/neutral, and blue/red for runners (for lights controlled from multiple locations).
Yes, there is ‘code’, but during those crazy post 2000 years where we saw mushrooming of houses all over the US, I’m sure some greedy contractors/developers cut corners. My point is: Yes, we’ve had building codes since the 60’s, but that does not necessarily mean all new houses built since then were built to code. Not to go off-topic, but heck, I just replaced a ‘Reduced Pressure Back-Flow Preventer’ for my sprinkler system. The old one lasted barely 15 years … To avoid modifications to the plumbing, I bought the same exact unit, and after reading the instructions, I found out the ‘SOB/Incompetent’ contractor installed the original one upside down. Not backwards (lucky for us) but upside down, where the drain holes were facing up!!!
PS. Just to be clear, I’m not approaching this from an amateurish DIYer layman … I studied way more complicated things than these in school (a long time back) and I have a dual advanced/graduate degree in mechanical/electrical engineering … I think I ‘know’ my way around these things 
I see the ambiguity is in my age addled brain. My mind glossed over the term switchbox. As noted by others, and, sadly, even me, switchboxes can quite easily have no neutral and be fine by code.
As I said I was confused, and wanted to understand…if I’d gone back and read things more than twice I probably would have seen my oversight. (Maybe it was the meds I’m on after the tooth extraction yesterday…or maybe I’m just an addled old sot. )
Also, to your point, I didn’t mean to imply you didn’t, in your words, “…know your way around these things.” After attaining my degrees while working as an electrician, I spent the better part of the last 50 years in “the field” doing everything from mechanical design to semiconductor physics. Care to guess how many times I’ve explained to PhD’s why residential power is not 2 phase but is split phase…? 
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No biggie … it took us several days to get through this discussion and one thing for sure, these things are complicated enough, without even adding the ‘local terminology’. My position is: we’re here to learn and exchange few ideas. In that regards, and thanks to the many people who have contributed, I think we met the goal. BTW: I’m new to this openHAB ‘frenzy’ and consider myself from the ‘learners’ camp … not the contributors (yet).
… peace. -
Also my reference to ‘… know my way around …’ maybe was not too appropriate, and I apologize.
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Care to elaborate on the 2-phase vs. split phase? I could google it, but sometimes people with field experience are better at explaining things than those with books
Back many years ago, in a country east of the Atlantic ocean, all buildings had 4 wires coming in. 3 phases + neutral, the so-called Y pattern. And, depending on whether one wanted to power small electrical appliances/light or a washing machine, one would pick either a Neutral + 1 phase (220 Volts) … or 2 phases (380 Volts)… or maybe it was 127/220 V … The way I understand it, some/most houses in the US have that a ‘similar’ option especially if one needs to run an electric (as opposed to gas) clothes dryer.
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Absolutely no apology necessary. 
And the frenzy does tend to subside. Well maybe, I say that standing in my house full of self designed mqtt IOT ESP32/Arduino boxes, Linux pc’s (including far too many Raspberry Pi’s), 3D printers, laser cutter, Bridgeport mill, 11x36 metal lathe, wood shop, electronics shop, chemistry that shouldn’t be in my basement…the list goes on. 
The 240VAC coming from the pole in residential US is a transformer winding with a center tap. Think of an old power supply with the output winding that had 3 wires, had 12V across the outer two wires, but 6V between the center tap and either outer wire. In the case of the residential service, replace the 12V with 240V. Then 120Volt between one line and the center tap IS out of phase with the other line to center tap (180 degrees). So if you want 240V, you connect between the lines (as happens for dryers, etc.) For the 120V outlets the connection is actually between one line and centertap, referred to as neutral.
See: https://en.wikipedia.org/wiki/Split-phase_electric_power
The 3 phase you refer to can be visualized as 3 transformers with one leg from each being connected together, this becomes neutral. The remaining 3 lines are the “hot” lines. The voltage between phases is 120 degrees reference to each other, and again the service can be connected between 2 hots, or between one hot and the center. That’s a Y “wye” pattern. There is also a delta pattern…
Some good visualizations here: https://electrical-engineering-portal.com/3-phase-transformer-connections
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Thank you. That explains why, if you start with 3-phases (wye pattern), the voltage options (2 phases or phase+neutral) are related by sqrt(3) i.e., 220/127 = 380/220 = 1.732 … whereas for the split phase, using the so-called ‘voltage divider’ (as you described), one gets exactly a factor of 240/120 = 2.
The wye/delta discussion takes me back over 30 years ago … to my college days. Back then, whether it was rigid body kinematics or electrical circuits, we did a lot of calculations ‘graphically’. But, I’m digressing once more.
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Yes, I remember one such presentation by an old school engineer with lots of diagrams to end up with a circuit that could be used to run 3 phase motors off single phase.
I also consider myself lucky to have graduated and then landed a job where I was mentored by a group of gents that I refer to as “classic” engineers. They were comfortable, whether they were in a machine shop, chem lab, or with a scope probe in their hand. I knew then I was never going to be the “specialist” engineer. And it was a enjoyable ride.