I’m new to HA; just ordered some gizmos for testing and have a configured Pi waiting.
I’ve been viewing lots of videos and much of the information appears to be slanted from the European electrical perspective. I keep running across some issue about the ‘neutral’ wire, and don’t understand what they’re talking about.
I realize Europe has no split phase and is 50hz. I don’t know what nomenclature they use to distinguish hot, neutral and ground, but I’d like to understand what the foreigners are talking about. When I go looking for a product on
and it cautions about neutral required or not I want to understand what the issue is.
I’m an EE so I understand things from the US perspective but this European neutral business has me wondering how they do their trivial house wiring and why there’s a distinction.
In europe lights are commonly connected to switch with live and light wire. Neutral wire is used usually on cross switches, if my translation is good. Meaning you can turn light from two or more switches. And I’m talking now about manual switches.
You can use live neutral and light wire if you want for single light switch but as I know most people dont use this.
In smart switch setup you will need a switch with neutral wire if your wiring require it, usually on cross switches. If not use switch without neutral. You can’t power switch that require neutral without it nor you can use switch without neutral on neutral wire setup.
In the U.S., a neutral wire is required in all junction boxes which includes outlet boxes, switch boxes and light boxes. All neutral wires are connected together and you never switch a neutral wire. The neutral is connected to earth ground at the circuit breaker box, and no where else.
All ground wires are connected together in all junction boxes they go through. At the circuit breaker, the ground wires are connected to earth ground, and no where else. Switches, outlets light fixtures, etc, usually have a ground lug that is also connected to the ground wire. You will often find these green pigtail wires used for this purpose:
I don’t think so. We have the same spec as you do. Live and light wire are just that. When you connect those two wires you got light. Neutral is just neutral. Ground wire is used in outlets and not switches. I’m not electrical engineer. I tried just to explain as I can.
@ddaniel is correct as I understand it. Here, in the UK:
lights mainly 2 wires (no neutral*)
sockets always 3 wires (with neutral).
Here’s a decent (UK) explanation that explains the 2-wire system (but it looks exactly the same as @stevemann’s diagram). It explains that the origin of 2-wires (ilo 3-wires) was to save cable during WW1 and WW2. It also explains how to wire 2 switches using 3-wires (thus avoiding a possible phase mismatch between switches)
You really can’t talk as the European Union as being one.
The electrical standards have not been run through the mill yet, so each country still have their own standard.
I am in Denmark, where we have one standard. Sweden have another and Germany have a third.
@stevemann did a wonderful job of getting the right images for the US explanation, the one I’m familiar with. It appears the issue is just terminology differences. I figured it had to be something like that since switch wiring is about as low as you can go; there’s nothing that can be removed to make it simpler.
BTW - Since you mentioned WW-II …
Here, on the island, an electrician told me to forget about the ground wire for the commercial site I was building because it’s not necessary and saves money. He was confounded when I insisted on ground wires, since I was supplying the wire. I wanted his crew’s labor, not his advice.
During the wiring, I happened to see his workers had shoved 11 wires into one piece of conduit when I noticed them struggling. They were trying to get the 12th wire into 1" flexible conduit. I told them to pull every wire out and there will only be 3 wires per conduit. I told them to not reuse the stretched wire (because it was stretched). They knew I was some crazy Gringo for sure then.
As i remeber they have 3 wires or more. I cant remember exactly but when i installed smart switches instead manual cross switches they pulled neutral wire on them. Maybe you are right, not sure.
There aren’t any terminology differences. Neutral in the EU is exactly the same as neutral in the US. The difference is the wire color (US: white, EU: blue) and the neutral to phase voltage (120V vs 240V). This has nothing to do with split phase when talking about lighting fixtures. In both regions, lighting circuits (and most outlet circuits too) are done with single phase wiring: one neutral, one phase.
Historically, no neutral was available in a switch box (but it is always available in outlets), because it technically isn’t needed there for dumb lighting. This was true in both US and EU. More ‘recently’ neutral has started to become available at switch boxes, making things like smart switches or modern dimmers easier to install. Dumb three way switches do not need a neutral either. They use a traveler switching the phase only.
When looking at single phase circuits, there is no difference between EU and US functionally. The grounding system is slightly different due to the use of GFCI’s at the breaker panel in the EU, but that doesn’t affect the neutral in anything after the panel.
Things become very different when talking about multi-phase circuits though (split-phase in the US vs three-phase in the EU).
No you can’t, at least not with the second diagram you posted. You need a neutral for an outlet, and there is none there. The second schematic is used for extending a normal 2 way (on/off) switch into a 3-way one after the fact, as both the lamp wire and the line wire are only available at the first switch.
A ground wire to the switch is not required if the switch is being installed in a metal box and grounded through the plaster ears. Even then I ground the switch just to keep the inspector happy.
Switches that have plastic housings will have a ground wire. In fact the manufacturer cannot obtain an Underwriter’s Laboratories (U.L.) approval without a ground.
