The title is still wrong.
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The US electrical system is not 120V
- Thread starter MZKM
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I'm originally from South Africa where the mains voltage is 240 volts. In a previous home in the USA we had wired the stove 240 volt circuit to SA style outlets for appliances that we brought with us (changed to a gas stove). But in typical US houses we have 120 volts for outlets with the exception of the dryer and cooker hookups which are 240 volts.
I use 230V phase+phase for my power amps and use 127V phase+neutral for DACs on both my systems.
Are you sure about those figures? 127 V single-phase, 220 V 3-phase systems have sometimes been used. Since you mention 127 V specifically, I suspect you have one of these that has been raised to match the newer 230 V standard. That would give a per-phase voltage to neutral of 133 V.
Yes, it is what I have measured here (São Paulo, Brazil).
Trouble Maker
Addicted to Fun and Learning
This kills me *I'm an EE by schooling, but never really practiced in the power/electronics area. I did rewire my entire house (1925 bungallow style farm house, pulled all new wire through the walls), new panel, new meter, new service (200A).
When talking about 200 amp or 400 amp service, this is per phase. So 400 amps is 120V*2phases*400A=96,000Watts
I can't imagine anyone ever using that much, it would cost you $11.52/hour to run at that rate (assuming average US electrical cost of 12cents/kWhr). Maybe, maybe only if everything in your house was electrically powered, and you had 3 water heaters, and 3 electric heaters, and you were running the oven, and had every light in the house on, and charging your 13 iPads, all at the same time. But most people in the US are running some of the big things off of gas or propane like house heating, hot water heater.
By NEC you have to dedicate 1.5amps/general light switch or outlet. And you can only use up to 80% of the circuits rating e.g. if you have a 15 amp circuit, you can only spec it up to 12 amps. In practice this means that you can have 8 things/15amp circuit if the are just lights or a general outlet. I can't remember if this is NEC, other building code in my area, or general best practice, but you also are supposed to have an outlet within 6' of any point on a wall. Probably so your average light or other thingamabob with a 6' cord can reach without an extension cord. OSHA or someone else says you aren't supposed to permanently connect something with extension cords, it's a temp thing and you should put in an outlet if you need 1 in that spot, but this might be work place specific. Then for kitchens and the like, you are supposed to have dedicated outlets for every appliance. We also did a big kitchen remodel after the electrical project. So our oven, vent hood, garbage disposal, dishwasher, microwave, and 2 (under-counter, smaller) refrigerator/freezers all have their own dedicated circuits. This is despite for some of them, 2 or 3 of them combined be under spec for one 15amp circuit. Then many things you connect now-a-days will consume less than 1.5 amps. Sure 20 years ago with incandescent bulbs you would want 1.5 amps for 1 light since that is only 180 watts. It would only take something like 2-4 of these at 1.5 amps to light up the whole interior of my house* all at once. This finally means that you have to way, way over spec the power coming into your house for some worst, worst, worst case scenario based off of power consumption of devices 15 years ago. The NEC is made by the industry who makes, sells and installs these devices (panels, wiring, outlets, circuit breakers), so they have every incentive to continue to increase the requirements since it will make them more money. They redo the code every 3 years and are continually increasing the requirements for ARC/GFIC fault detectors. A basic break is maybe $5 where the full ARC/GIFC is about $50. Just in the few years form when we did the main electrical project to when we did the kitchen there were increased requirements in the kitchen area.
I installed a panel with a manual switch over to run a backup generator and got a harbor freight generator. The panel also has power meters for each phase in it (only for backup feedback circuit, not for mains incoming circuit). Cheapest/easiest way to do it, essentially whole house power backup for ~$1k but it's manual rather than automatic. We got a ~9kwatt generator. I ran some test loads out to check everything, make sure my concept of what we could run would work, break in the generator with a real load. My idea was I just wanted lights, heat, refrigerators. In reality our house* can just about run off of 9kWatts with everything running. But we have 48,00Watt service.
*Our place is only about 1200sqft, so it's not a huge place like the new Mc Mansions you are talking about.
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Take two Tesla Model 3 and Y at 240v and 48 amps each add in AC in a warm climate at something like 40A x three or even more units.
Older Tesla model S could charge at 80A! Although Tesla learned this was overkill and I believe all the new models are now 48A as well.
I have a detached garage with only a 60A subpanel so I can only charge at a 40A rate as I need things like lighting, the garage door opener and outlets.
Older Tesla model S could charge at 80A! Although Tesla learned this was overkill and I believe all the new models are now 48A as well.
I have a detached garage with only a 60A subpanel so I can only charge at a 40A rate as I need things like lighting, the garage door opener and outlets.
Trouble Maker
Addicted to Fun and Learning
Good point. My wife had a Volt before, and our garage is not equipped with a high power feed yet. We have 3-15amp lines running to it. So we were just charging it at 1.4kW, it could only go up to I think 3.8kw anyway. Plus with it being a PHEV it wasn't really an issue. Even at 1.4kW, on weekdays she rarely had an issue with getting a full charge overnight. The rub was on the weekends if we went somewhere in the morning, then in the afternoon.
She is planning to get probably a Bolt when we go back to the US here in a few months. I'll probably do a small rewire and use 2 of the lines to get up to 3.8kW level since the Bolt is only EV. I think it can do up to 7.2kW, but we don't have the lines to the (detached) garage for that. Still we will have 2 other gas cars, so even if we can't use the Bolt due to low charge it won't really be an issue.
Eventually we will replace the garage (only 1.5 car now and I want a 3+car) and I will put a sub panel out there. Probably just do a 100amp or more panel to future proof it and have plenty of circuits available.
Even at 'just' 10kW charge rate, you could charge the largest of all of the EV vehicles that exist battery overnight. At the 40amp charge rate, you are right around there. How is it living with that charging rate at home? That's driving 200miles+today, charging overnight, then doing it again the next day. At that rate even if you only did it 5 days/week you would rack up 52kmiles in 1 year. I don't really see the point of needing to charge much faster than that. Especially since most people right now have more than just EVs at home. Long term I don't think the viability of EVs hinges on any faster at home charging, but on more availability of faster charging structure at work, shopping, rest-stops, etc.
Still, we are talking about these cars charging which have huge draws compared to most household items and we are still talking about 40amps, 48amps, when some people are putting 300amp or 400amp services in their homes. One could have 2 of those 80amp charge rate older model 3s and still not use half of that size service.
She is planning to get probably a Bolt when we go back to the US here in a few months. I'll probably do a small rewire and use 2 of the lines to get up to 3.8kW level since the Bolt is only EV. I think it can do up to 7.2kW, but we don't have the lines to the (detached) garage for that. Still we will have 2 other gas cars, so even if we can't use the Bolt due to low charge it won't really be an issue.
Eventually we will replace the garage (only 1.5 car now and I want a 3+car) and I will put a sub panel out there. Probably just do a 100amp or more panel to future proof it and have plenty of circuits available.
Even at 'just' 10kW charge rate, you could charge the largest of all of the EV vehicles that exist battery overnight. At the 40amp charge rate, you are right around there. How is it living with that charging rate at home? That's driving 200miles+today, charging overnight, then doing it again the next day. At that rate even if you only did it 5 days/week you would rack up 52kmiles in 1 year. I don't really see the point of needing to charge much faster than that. Especially since most people right now have more than just EVs at home. Long term I don't think the viability of EVs hinges on any faster at home charging, but on more availability of faster charging structure at work, shopping, rest-stops, etc.
Still, we are talking about these cars charging which have huge draws compared to most household items and we are still talking about 40amps, 48amps, when some people are putting 300amp or 400amp services in their homes. One could have 2 of those 80amp charge rate older model 3s and still not use half of that size service.
Power...
I'm a mini-power hog. 2600 sq feet, all electric.
Estimate, usually weekly measures, as daily averages.
Blue is base, Red is Air Conditioning stacked on top.
Last summer was kinda hot.
I'm a mini-power hog. 2600 sq feet, all electric.
Estimate, usually weekly measures, as daily averages.
Blue is base, Red is Air Conditioning stacked on top.
Last summer was kinda hot.
Trouble Maker
Addicted to Fun and Learning
That right there is the data we are looking for. Big (but basically average for new home size in US now) house, all electric, in Florida swamp ass hot summer. Over an average day still not using what a 400amp service can pull in 1 hour.
It's kind of funny to see that there is basically never a time of year, on average, that you don't use A/C. NO THANKS, I'll stick to the northern climates.
I need to get some power monitors in my panel. What are you using?
It's kind of funny to see that there is basically never a time of year, on average, that you don't use A/C. NO THANKS, I'll stick to the northern climates.
I need to get some power monitors in my panel. What are you using?
Think about class D if you haven't already.
I just read the electric meter and the hours on the heat pump thermostat on Wednesday night when I remember to, or as soon as I remember that I didn't. Plug two numbers into a copied from last week row on a spreadsheet.
Using an estimated 4.6kW draw for the AC/Heat, apportion the usage.
That value makes the base usage pretty steady, so I figure it isn't too far off. It is labeled on the air handler as 5kW.
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Ray you need to break out the pull of the Krells daily separate from everything else.
restorer-john
Grand Contributor
I thought about solar, decided against it at the time, invested what I would have spent on the Utility (TECO) stock, the dividend pays the bill, the utility sold itself to Emera, collected a substantial capital gain, bought the new shares, and have some more gain and dividends still.
Then the utility started building solar farms nearby.
The JBLs are the daily drivers now, 5W each.
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Not if you have an old school electric clock. That 60 hz is what kept it accurate. Now days with the 60 hz being very tightly controlled those old clocks keep better time than ever.
Going solar/off-grid is very reasonable in these times.
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