Arcam
Living the Tesla Nightmare
That's interesting, so you get 2 taps on your incomming supply?
sorry, I did mean 120v, I was thinking of a shaver socket
sorry, I did mean 120v, I was thinking of a shaver socket
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It's called "split phase".That's interesting, so you get 2 taps on your incomming supply?
sorry, I did mean 120v, I was thinking of a shaver socket
Split-phase electric power - Wikipedia
I would basically say 3 tap points. In our electrical panels, we have two connections that are the two opposite points of a 240V sine wave. But then we also have a center tap, which is the neutral, that generally stays at 0V.
For the 240V connections, you connect the circuit from one hot side to the other hot side. For the 120V connections, you connect from either one of the hot sides to the neutral in the middle.
eprosenx
Active Member
Residential in the US is 120v/240v single phase, but "split phase".
So there are three wires coming from the utility transformer into your house.
Two hots and one neutral.
The Neutral is tied to ground at the transformer and at the building service entrance location.
Voltage from hot to hot is 240v (nominal). Voltage from either hot to neutral is 120v (nominal).
So you get both when you order electrical service here (you can wire things up either way). As @Rocky_H points out, we use 120v for basically all general purpose lighting and plugs around the house, but then large loads like the Oven/Range/AC/Water Heater, etc... are 240v.
If we were going to redesign the electrical system here from the ground up I am curious what modern best practice would be. I suspect a higher voltage to all the household convenience outlets would be adopted since insulation has gotten much better and less expensive over time while copper wire has gotten more expensive. But there is basically no chance of a change here since there are so many devices already in use that it makes switching virtually impossible.
Note that we also use 60Hz AC while much of the rest of the world uses 50Hz. Some have said 50Hz is safer for humans? I don't know, I have not dug deep into that one.
Edit: I was writing this as Rocky posted something and I failed to refresh before submitting. He covered most of this!
Arcam
Living the Tesla Nightmare
I can see the lower voltage argument to a point with very old consumer/fuse boards, but what at whatever load for the same wattage the cables on 120v need to be twice as thick. I understand that it is too ingrained now in the US to change over, can your 220v supply still give 100A?
Sorry, this is digressing from the original post, happy to leave it here.
Sorry, this is digressing from the original post, happy to leave it here.
Yes, Nosecone Tesla's could do 80amp charging at 240v, which required a 100amp circuit, but that is hardwired into the circuit.
/edit. The biggest "plug" we have on the NEMA chart is 60amps at 240v. There are also larger plugs available for 277v but you don't see 277v really outside of industrial settings, it's not something available typically in residential.
/edit 2. Chart of US plugs showing amps and volts: MTI Corp - Leading provider of lab equipments and advanced crystal substrates
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Yep. And a lot of houses have a 200A feed. Though I can't imagine what single device you would use that could draw that much. (Maybe if you wanted to put your own Level 3 DC charger in your garage?)
You're still stuck on that "same wattage" thing. What kind of wattage are you talking about? Like I said, any of the regular household products are low power, so 14 gauge or 12 gauge wire can be used for that stuff, because they never go over about 15-20 amps. That's still pretty thin wire. Any loads that DO require higher power, where the wiring thickness might be a problem with 120V, just DON'T use 120V.
Arcam
Living the Tesla Nightmare
It was just an observation on the AWG of the cables required to supply the same piece of equipment. In the UK we would typically use 14 gauge (1.5mm) for lighting circuits and 10 gauge (2.5mm) for 32amp ring mains (effectively 5mm cable - 2 * 2.5mm) all or course at 230v.
I am presuming that either "live" combined with the neutral could supply the 120v rail in a property, would a typical property balance the load between the 120v rails with say the ground floor on one and the upper floor on the other?
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eprosenx
Active Member
We usually have a lot of 120v circuits in the house for various things, so yes, they are balanced across the two “hot” legs as you describe. If you look at a USA circuit breaker panel each alternating spot is on the opposeite phase leg. So if you install them in order you will get aboit half on each hot.
If you install a double wide breaker it spans two hots and gives you 240v.
So on your “ring” circuits, do you attach both ends back to the panel? How about for your lighting circuits?
richrootes
Member
It was a real eye opener when we moved from the UK to Canada - the household wiring is one of the few things I miss from the old country.....
eprosenx
Active Member
Great video, but I totally disagree that the UK plug is the best. It is friggin huge!
The feature he talks about where the pins are partially insulated I am positive they were added later to reduce danger. They were likely forced into this as the large plug size made it easy to zap yourself with a partially plugged in plug.
Mainland Europe has similar insulated pins on their plugs too.
The US now requires tamper resistant receptacles for all new construction. They function similarly to what was described in the video (though the ground is not the trigger since many small US appliances do not require a ground).
I also am not convinced that having a fuse in the plug is a great idea. Many consumers are not capable of troubleshooting that. Though maybe the biggest downside is the physical size of the plug required. If it was such a great idea I would assume it would have caught on elsewhere in the world (which I have not seen).
I actually like IEC plugs (used in datacenters), though they need ways to be held into the receptacles so they don’t fall out. That is their downside. C13/C14 and C19/C20 are the common ones we use.
Arcam
Living the Tesla Nightmare
Makes sense, I looked at the Wiki article that RockyH posted up earlier.
So you can get 100a at 120v and 200a at 220v, we only get 100a at "230v" (I get 244v) single phase on domestic circuits. The UK used to be 240v nominal but with the rest of Europe at 220v the "standard" is now 230v across Europe. The weird thing is we just expanded the tolerance to meet that standard
So we were 240v +/-6% now we are 230v +10/-6%.Ring mains start and end at the same breaker, single ended low power circuits are 16a max and lighting circuits are again single ended and normally 6a. All other high power circuits like showers, electric hobs, EV chargers are all single ended 32 - 40 amp.
Well, um, possibly...in theory...maybe. But that's just not something that is done. No one would ever use 120V for a 12kW power circuit. They don't make 120V breakers that big. That's what I keep mentioning about 120V only being used for the low power circuits because of that wire size issue.
I'm really confused and don't understand what this means at all. Physically there can't be any such thing as a "single ended circuit". Circuit sounds like the word "circle" for good reason. All AC circuits must be a closed loop to have any current flow at all. So I am assuming that the phrase "single ended" is kind of a nickname for some way of connecting them. From the breaker at one end, what do the other ends of these circuits connect to for their return path?
In the U.S. wiring system, all circuits--both 120V and 240V--have a full return path back to the breaker at the electrical panel, so they are all complete loops. ("rings", as you would say)
Arcam
Living the Tesla Nightmare
You are very close on the understanding of single ended, it is when one end it attached to the socket and the other the breaker with no loop back, we have limits on how many sockets may be daisy chained like this. So we would run 3 core (normally 2.5mm) which would carry the live, neutral and earth so no "return" path is required, all EV charging points are wired this way.
The ring main is as you describe with both live ends coming back to the breaker and neutral/earth tags to their respective points in the fuse board.
Oh. Well, the terminology is just funny then. You say there is no loop back. But then you say the wiring runs have live, neutral, and earth. The Neutral IS the loop back. That's exactly how our 120V circuits are.
Arcam
Living the Tesla Nightmare
Sorry yes, you are quite correct in what you say, the neutral is the return. I was attempting to differentiate between a Ring and non Ring.
Now you guys should go back and forth on the proper pronunciation of aluminum.
Notice how there is no letter i after the v in mischievous?
DMC-Orangeville
Audi eTron & John Deere 5100E
You spelled it incorrectly. It's aluminium.......
Darn American spelling. It's
Colour
Neighbour
Theatre
Centre
geesh.......
Many thanks for this information. Just had my wall charger installed this morning on a 100amp circuit. Try as we might, we couldn't get it to show it was drawing 80amps on setting "D" on the dial. B showed 64, C showed 72, but D showed 72 as well (instead of the 80 listed in the charger manual) and it had me and my electrician stumped. Sounds like the Model S will only draw 72 regardless as a max?
Also went through the "lockable" discussion for the breaker, so glad to see that was expected as well.
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