The US electrical system

[tooki]

The idea of 400A 240V service to me is just baffling.  In the UK it's rare to see any home over 100A 240V service, single phase, and many older homes have 63A or 80A service.  Some larger homes have 125A.

This creates a real hassle for EV adoption because there isn't enough local capacity to have two car chargers @ 32A each on someone's driveway.  Many DNOs (the local network operators) have designed the power distribution networks with the assumption that all customers will use an average of 4-5kW at peak.  That falls apart when people are charging their cars and heating/cooling their homes with heat pumps. Local upgrades are going to be necessary.

Don’t you have 400V three-phase service for major appliances? (Here in Switzerland, that is quite common.)

[duckduck]

As a 'fun' diversion here...   
Many years ago in the bush, (I worked for that power authority), we would just string a 'clip' up
to the powerlines above with a pole, when out on the road. And connect it to a 're-wired' 30-Amp
kettle to make coffee. Took about 15 secs to boil !! Though it shook like hell,  haha...   

Also, in regards to effective energy management, ref a few times in this post...
I also worked more recently with a major company, ('Honeywell' actually!), where I was responsible
(amongst countless other things/equipment) for Energy Management systems in multi-story buildings.
Now, 'some' buildings owned & occupied by one company, are 'interested' in such savings...
However, multi-story bldg owners with MANY other companies residing within, would SCOFF at my
offerings of savings!!!  Why?... Because they would individually meter the whole bldg, and on-sell the
power to all the bldg customers!  Often making from $100,000 to $500,000 profit, JUST from re-sale
of electricity per year!!  They actually WANTED all their customers to be as in-efficient & wasteful as
possible!!  Always made me laugh, when the Govt was pushing for 'efficient' buildings... hahaha...   

Love the kettle. I would watch from a distance    I have much respect for the people that build and maintain the electric lines. When I make a mistake I might burn up a fancy LED or a $6 opamp.

Off topic but apropos, there is little incentive to improve the fuel efficiency of cargo ships because most ships are leased (ball park of US$10,000 per day) and the lessee pays for fuel. The ship owners couldn't care less. Large shipping companies that buy their ships outright e.g. Maersk care very much about fuel efficiency because it directly affects their bottom line.

[schmitt trigger]

If people think that 120 volts is too low a voltage for the larger loads (a thought which I also share, BTW), in Japan it is only 100 volts.

[themadhippy]

Don’t you have 400V three-phase service for major appliances

As mentioned above 3 phase in domestic premises is rare in the uk.I can only think of 2 occasions ive come across it in 35+ years and both were much larger than the average  2up 2 down.

[IanB]

The idea of 400A 240V service to me is just baffling.  In the UK it's rare to see any home over 100A 240V service, single phase, and many older homes have 63A or 80A service.  Some larger homes have 125A.

I was curious when he talked about 200 A service in the video, and then he showed a "small" pole mounted transformer which presumably provided the supply. I know those transformers are bigger than they look when they are down on the ground, but I still wondered how many lots of 200 A it could supply before being overloaded?

[Gregg]

It seems that no matter what the local electrical standards may be, there always seems to be ways of making electrical devices work.
The larger the demand for electrical distribution built to a given standard, the better the selection and price due to scales of economy.  The differences do make for interesting discussion 

Perhaps a far more interesting topic may be why 60Hz or 50Hz became standard.

[james_s]

I was curious when he talked about 200 A service in the video, and then he showed a "small" pole mounted transformer which presumably provided the supply. I know those transformers are bigger than they look when they are down on the ground, but I still wondered how many lots of 200 A it could supply before being overloaded?

Those "pole pig" transformers are typically 20-30kVA, often they have the kVA printed right on them. They are big, typically 3'-4' tall and weigh several hundred pounds. They may supply from one house to 5 or 6 houses depending on the logistics, they try to avoid running 240V over runs of more than a few hundred feet.

[Monkeh]

I was curious when he talked about 200 A service in the video, and then he showed a "small" pole mounted transformer which presumably provided the supply. I know those transformers are bigger than they look when they are down on the ground, but I still wondered how many lots of 200 A it could supply before being overloaded?

Those "pole pig" transformers are typically 20-30kVA, often they have the kVA printed right on them. They are big, typically 3'-4' tall and weigh several hundred pounds. They may supply from one house to 5 or 6 houses depending on the logistics, they try to avoid running 240V over runs of more than a few hundred feet.

... a 30kVA transformer won't handle a single 200A service.

And we're the underbuilt ones?!

[tooki]

Perhaps a far more interesting topic may be why 60Hz or 50Hz became standard.

This paper has a quite comprehensive summary of the reasons: https://www.djtelectricaltraining.co.uk/downloads/50Hz-Frequency.pdf

[james_s]

... a 30kVA transformer won't handle a single 200A service.

And we're the underbuilt ones?!

I don't recall anyone saying anywhere is underbuilt?    Or do you just like being a dick?

I may have been mistaken in the rating so I just went and looked, the (pad mount, underground wired) transformer that feeds my house and I believe 3 others is 50kVA. This is as far as I know the continuous rating at max ambient temperature. A 200A service will *never* be pulling 200A continuously and it's typical to have 300A-400A cumulative in branch circuits off a 200A main, nobody is ever going to load them all up 100% at the same time. I've seen as small as 5kVA, I don't know what those are used for and at least as large as 75kVA. The only transformer of this type I've personally messed with is a 25kVA unit we used to step up 240V to 4800V to power a series streetlighting regulator, it was the smallest 4800V transformer we could find at the scrapyard.

Anyway suffice to say whatever we have here is clearly adequate, I've never seen my line voltage lower than 119V or higher than 123V at this house and it's extremely rare for a transformer to burn up outside of damage from a lightning strike.

[Monkeh]

... a 30kVA transformer won't handle a single 200A service.

And we're the underbuilt ones?!

I don't recall anyone saying anywhere is underbuilt?    Or do you just like being a dick?

https://www.eevblog.com/forum/chat/the-us-electrical-system/msg3104258/#msg3104258

I may have been mistaken in the rating so I just went and looked, the (pad mount, underground wired) transformer that feeds my house and I believe 3 others is 50kVA. This is as far as I know the continuous rating at max ambient temperature. A 200A service will *never* be pulling 200A continuously and it's typical to have 300A-400A cumulative in branch circuits off a 200A main, nobody is ever going to load them all up 100% at the same time. I've seen as small as 5kVA, I don't know what those are used for and at least as large as 75kVA. The only transformer of this type I've personally messed with is a 25kVA unit we used to step up 240V to 4800V to power a series streetlighting regulator, it was the smallest 4800V transformer we could find at the scrapyard.

50kVA makes more sense - at least it's capable of 200A. And yes, I get that in normal conditions you're not going to see full load from a single building, but it's not a 200A service if there isn't 200A behind it.

[Stray Electron]

7kw to dry yer clothes, aint you guys heard of washing lines

   Seriously, not since the 1960s. Besides with the now popular zero lot line subdivisions, there's NO room for one. I literally haven't seen a clothes line since probably 1968.

[tom66]

My clothes dryer uses 2.2kW and a total of ~2.7kWh to dry 8kg of clothes straight from the washing machine.

I don't understand how you'd need 7kW to dry clothes. One of the important things is to not overheat the clothes which damages fabrics and risks fire.   

[ciccio]

About NEW meters, I know (by experience) that the new electrical meters installed in Italy can be remote controlled (using some kind of signal over the power line) allowing the Utility Company to:
-read your meter, and bill you according to the (optional) tariff that changes day/night and workdays/weekends
-reduce the tripping current of the meter (if you forgot to pay a bill, the max power available will be reduced  from 3.5 kVA to 0.5 kVA for (I believe) 15 days, then to ZERO ).

Now they changed my GAS meter with a new one than can do the same things. It uses some kind of Wi-Fi (with some problems because most meters are installed in metal enclosures) and will allow for remote reading the meter and remote cutting off the gas supply.

Cutting the gas supply to a defaulting customer required physical access to the meter, that in old buildings is many times inside the house, and this created problems to the field technicians. Now the supplier can do this from their control room...

[bdunham7]

... a 30kVA transformer won't handle a single 200A service.

And we're the underbuilt ones?!

You'd have to understand what that rating means to make that statement.  Where I live, one 25kVA plated xformer is feeding 4 houses that were originally built 50 years ago with 100A service, but with many upgraded to 200A since.  If they need service, the utility company is swapping them out for 50kVA versions, but mostly they are still fine.  Using too large a transformer increases losses at low power, so they use low-Z oil-cooled transformers that can sustain massive overloads from their rated power.  IIRC, a typical xformer of this type can sustain a 175% continuous overload at 68F ambient and a 400% overload for an hour.  Or something like that. 

[bdunham7]

My clothes dryer uses 2.2kW and a total of ~2.7kWh to dry 8kg of clothes straight from the washing machine.

I don't understand how you'd need 7kW to dry clothes. One of the important things is to not overheat the clothes which damages fabrics and risks fire.

'merica.  Everything is bigger.  My first car had a 7.5 liter engine. 

[Halcyon]

Electromechanical spinning disk meter on my nest. I'm not a big fan of "smart" meters or "smart" anything else. Also, get off my lawn.

 

[free_electron]

I'm shocked by the 200 Amps main breaker.  Here in Italy a standard family has a 3.0 to 5.5 kVA contract, which means a 16 or 20  Amp breaker.

do you have any idea of the load of a 5 ton airco unit ? that thing pulls 30 to 32 ampere on a hot day ... throw in an electric water boiler, a 5 kilowatt oven (or a double one)  , a 3 kilowatt cooktop , a  2 kilowatt microwave, a 2 horsepower food disposal unit , a dishwasher, washing machine and electric clothes dryer,  a well pump , a 2 hp pool pump , 1kw saltwater chlorine generator,  ... yup you need that 200 ampere !

I just bought a new home. Planning to go solar... looking at a 16 kilowatt array with 4 battery units.... covers 120% of my usage.

[NiHaoMike]

do you have any idea of the load of a 5 ton airco unit ? that thing pulls 30 to 32 ampere on a hot day ... throw in an electric water boiler, a 5 kilowatt oven (or a double one)  , a 3 kilowatt cooktop , a  2 kilowatt microwave, a 2 horsepower food disposal unit , a dishwasher, washing machine and electric clothes dryer,  a well pump , a 2 hp pool pump , 1kw saltwater chlorine generator,  ... yup you need that 200 ampere !

The demand can be way reduced with smart engineering, even if 5 tons of A/C really is needed. (Hint: if your insulation is decent, it's unlikely unless you truly have a huge house.) The water heater isn't going to need to run at full capacity when the A/C is needed at all, plus one based on a heat pump reduces the power usage down to a few hundred watts. The oven is only going to draw full power during preheating, same with the cooktop. The microwave is only used for short bursts and the disposal for even shorter. Heat pump dryers also use much less power. The pool equipment doesn't need to run full time so a smart controller can run it when demand is low and/or energy is cheap.

[cliffyk]

At first I had a problem watching the video as I could not get General Trelane, the lonely Squire of Gothos out of my mind:



That and that it started out with the fellow prattling on sensationally about a bunch of stuff I learned in 8th Grade shop class kind of shot his credibility right off the bat. However once I saw where he was going it was not bad.

Maybe I missed it, but it did seem that he glossed over or did not emphasize that the so-caled "neutral" wire in our silly earth return split phase system is anything but neutral. It carries the full difference of the loads applied to each phase. If you draw 200 A from 120 V phase "A", and 100 A from phase "B", the "neutral" wire will be carrying 100 A--enough to be a BIG surprise for anyone believing it to be "neutral", and mucking about with it while the full phase load is unbalanced.

[CatalinaWOW]

All of these comments about service capacities in America are just snapshots in time.  I presume the same thing is true in the rest of the world.

I vividly remember a visit to my grandfathers house when an immense blizzard occurred.  It was electrified in the 1930s through an effort called REA in the US (Rural Electrification Association I believe).
When all power in the house went out I was sent out to check the fuses (old Edison base glass fuses), particularly to see if the main fuse had gone.  I reported back that the largest fuse I could find was 30 Amps and it couldn't be the main, so where was the main fuse.  Turns out that was the main and a surge had taken it out.

The house I grew up in was typical for its time (mid 1940s construction) and had 60 Amp service.

By the time I was starting to look at home buying 100 Amp service was common, but not dominant

Another twenty years and 200 Amp service is close to becoming standard.

While the values may be different I would bet that much of the rest of the world has a similar trajectory.  As worldwide wealth increases the number of electical gadgets, from kettles, to TVs, to hair dryers and computers and air conditioners is growing.

[cliffyk]

The first house we owned was a 3-room "winterized" summer cottage on a 50' x 80' lot (we paid $2700 for it in 1964)--it had a 30A "Edison" fused entrance, "knob and tube wiring", and an LPG floor furnace that you did not care walk on barefoot and gobbled up over 500 lbs. of propane / month in January and February. Taxes; IIRC were $65 a year...

[james_s]

My clothes dryer uses 2.2kW and a total of ~2.7kWh to dry 8kg of clothes straight from the washing machine.

I don't understand how you'd need 7kW to dry clothes. One of the important things is to not overheat the clothes which damages fabrics and risks fire.

I've never seen a 7kW clothes dryer. Mine is a big Maytag unit with a 5.5kW heater, many are around 4kW. The circuit capacity is 30A, that doesn't mean the dryer draws 30A. The next size down is 20A and that is insufficient for a 5.5kW dryer.

I think the wattage of the dryer is a rather useless metric though, what matters is the kWh required to dry a load of clothes. A lower powered dryer will consume less instantaneous power but all else being equal it will run longer. Seems like mine takes 30-40 minutes to dry a full load out of the washer, and it handles 2-3 times the load of a typical UK dryer. Bigger capacity machines are run less frequently, I doubt there is that much difference in consumption per item of clothing.

[NiHaoMike]

I think the wattage of the dryer is a rather useless metric though, what matters is the kWh required to dry a load of clothes. A lower powered dryer will consume less instantaneous power but all else being equal it will run longer. Seems like mine takes 30-40 minutes to dry a full load out of the washer, and it handles 2-3 times the load of a typical UK dryer. Bigger capacity machines are run less frequently, I doubt there is that much difference in consumption per item of clothing.

A heat pump makes a big difference there. Or even a heat recovery exchanger, for that matter.

[cliffyk]

My clothes dryer uses 2.2kW and a total of ~2.7kWh to dry 8kg of clothes straight from the washing machine.

I don't understand how you'd need 7kW to dry clothes. One of the important things is to not overheat the clothes which damages fabrics and risks fire.

I've never seen a 7kW clothes dryer. Mine is a big Maytag unit with a 5.5kW heater, many are around 4kW. The circuit capacity is 30A, that doesn't mean the dryer draws 30A. The next size down is 20A and that is insufficient for a 5.5kW dryer.

I think the wattage of the dryer is a rather useless metric though, what matters is the kWh required to dry a load of clothes. A lower powered dryer will consume less instantaneous power but all else being equal it will run longer. Seems like mine takes 30-40 minutes to dry a full load out of the washer, and it handles 2-3 times the load of a typical UK dryer. Bigger capacity machines are run less frequently, I doubt there is that much difference in consumption per item of clothing.

The "Whole Picture" is, for many, a difficult concept to grasp--this is why "waterfall" projects generally fail...

It's akin to Squire Trelane's (apparently due to a prior video); getting roasted for supposedly stating 120 VAC was "safe"--he did not, he said it was "safer" which is a factual statement...