Ground is just the bulk electrical potential of the earth (which is why grounding rods are just driven into ... well, the ground).
You are pretty much always connected to ground though some resistance. It can be really low (i.e., touching a wire or fixture that is directly connected to the aforementioned grounding rod). It can be really high (i.e., rubber soles of your shoes on a wood floor with polystyrene insulation).
There are pragmatic limits. For example, electrical tape is rated for something like 600V per mil. The resistance is so high as to be considered infinite under those conditions. In my industry, voltages are >100,000V. People have been seriously injured by taking large steps, due to voltage gradients on the surface of the ground itself!
There is also a capacitive element, though I may be getting into the weeds a bit. Two points may measure infinite impedance with a multimeter, because it is taking a DC measurement. In reality, there may be enough capacitance for the AC voltage to push and pull charge (current) through you at line frequency.
V per mil is a measure of electric field strength...this is different than resistance (ohms or volts per amp). All insulating materials (including air) are rated as to what voltage over what distance will cause them to break down...this is known as their dielectric strength. Resistance is related to HOW MUCH current (energy) will flow through something, with dielectric strength being how much voltage will cause an insulating material to break down and allow current (energy) flow. Probably WAY too deep for this forum, but wanted to correct a misstatement.
@lcw731: The first book looks good. I wouldn't buy the second book unless you want to know more about how electricity works.
Yeah, it is tough to know where to draw the line and I was a bit fast and loose with nomenclature. Still, R is always (V/I), but it is not a fixed value across all conditions. E-tape has a really big Resistance, until it doesn't due to over-voltage. That is what I was trying to convey with "under those conditions", but my communication often fails short of its intent.
That is pretty cool. Lots of people are still gainfully employed to characterize, simulate, and exploit the observed behavior of electricity.
25 years ago, I attended a seminar hosted by Lutron regarding dimming fluorescent lamps. A professor was visibly frustrated and saying things like, "the lamp doesn't want to do that!" When you spend too much time on this stuff, it becomes a sentient being with desires.
Did I mention that I hate wire nuts? I was tracing a circuit with 3 lights and 3 switches and came across this monstrosity in my basement. Lots of other problems, but they are complicated by tangled twists.
Finally got around to doing the first project today (was waiting for my wagos to arrive.
Installed according to the instructions sent by @agnes.zooz last week. It does not actually turn the lights on or off physical or digital.
Tried the smart start inclusion ( I really fail to se what the advantage to smart start is), as has been my usual experience just says pending in the app, BUT I did have a device (not with the name or location I provided in the Smart Start inclusion) appear in my device list.
This is the only smart dimmer (or switch for that matter) That I currently have installed. Clearly its getting power, because its showing up and logging. So what Am I doing wrong?
I am far from an expert on these nuances, but something seems amiss to me with your combination of Scene Control - Disabled and Smart Bulb Mode - (both) Disabled... Is that a combination Agnes suggested?
Perhaps that's totally correct, but the way Zooz tries to explain those Smart Bulb Mode parameter options is all hella confusing (at least to me)...
From the Z71 support page, so Param # may not line up...
UPDATE:
I grabbed another dimmer, uninstalled the first one (Pictured) , and installed the 2nd. Didn't work the first few times. finally got it to work after trying a few different configurations with wires. Ended up working with: LOAD Top Hole, LINE bottom hole, NEUTRAL Top Hole (I think that is the one that finally made the difference.
I don't know if the other dimmer is bad, or if it was wiring, as I was never able to get it to actually respond beyond just what was showing up in the logs.
Huh, that would be odd -- I assume you are referring to the 2 vertically-aligned holes at each "spot"? It shouldn't matter at all which one the wire goes in, but whatever works! As long as the wire is seated in there right and tightened down well, you should be all set.
If still wonky power behavior, play with the Smart Bulb Mode parameter options -- I would think you'd want the default which is "physical paddle control enabled", but again, those Zooz descriptions really give me a headache trying to decipher.
I have a Z71 that is wired line-only (no load) that I use solely as a scene controller -- My Smart Bulb Mode is "Physical and ZW control disabled" (and Scene Control - Enbaled), and it works great -- that Smart Bulb Mode setting seems completely unintuitive to me, but so it goes lol
This dimmer is connected to 4 can lights. Right now non are smart, just dumb ole dimmable cans. I have thought about putting RGB in these (mainly for night vision purposes , we not into all the crazy colors too much. Based on a converstion with a guy at church, I'm not even sure these are able to be changed like that. .You are correct I do want the physical control enabled. ill take a look at it.
I had already closed it all up, but Once I saw your comment, I went ahead and pulled it apart and shortened those wires just a hair. I hadn't even noticed, and it's better to be safe than sorry!
