The US electrical system

[rstofer]

If you are in the US and  you have an heater in a room, (e-g- an electric stove), it will be powered via a ridicolus plug at 120 V. The plug will overheat and a fire will start, in the standard US home built with wood.
When I was in Seattle 20 years ago, I noticed a lot of firetrucks passing by, a lot more than was usual in Europe.
My US friend said: it's normal, Christmas is coming...

That is just wrong!  I can't even imagine an oven or stovetop that isn't running on 240V.

stove, noun, "A heater, a closed apparatus to burn fuel for the warming of a room."

Not a great leap to realise he's not talking about your kitchen stove.

It never occurred to me to call a portable heater a stove.  Most of the portable heaters (also called space heaters) I have seen are on the order of 1.5 kW or about 12.5 Amps.  That is slightly more than a 15A breaker wants to provide on a full time basis.

Some come with 'tilt' switches to shut them down when they are turned over.

As to 'stove':
https://www.merriam-webster.com/dictionary/stove

Definition of stove (Entry 1 of 2)
1a: a portable or fixed apparatus that burns fuel or uses electricity to provide heat (as for cooking or heating)
b: a device that generates heat for special purposes (as for heating tools or heating air for a hot blast)
c: KILN

The stove is sometimes called a range but both terms are used in the US.  The term stovetop (one word) comes up when searching Home Depot:
https://www.homedepot.com/c/ab/types-of-stovetops/9ba683603be9fa5395fab90a04794ac

[james_s]

In all of North America, the newest utility meters can turn off the power to your house without even going outside the main power station

Not just limited to  america,but anywhere were smart meters are installed.However that aint the worst aspect of smart meters,with them the utility providers are now able to measure your  power factor and charge accordingly

clothes dryer is probably 30A at 240V.

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

I've had a smart meter on my house for the entire 15 years I've lived here, recently it was upgraded to a newer style. In neither case did it have the ability to cut the power remotely, if they want to cut the power they have to either physically yank the meter or disconnect the feed at the distribution transformer. It's possible that US-style smart meters capable of remote cutoff exist but I've never seen one.

Just because the dryer circuit is 30A doesn't mean the dryer draws 30A. 5.5kW is typical of an electric clothes dryer. Clothes lines exist but they are rare here, electricity is cheap in most states, half to one third what it costs in the UK and a large number of residential areas have those horrid HOAs that ban clothes lines among other things. Obviously  urban city dwellers don't really have it as an option either.

[james_s]

If you are in the US and  you have an heater in a room, (e-g- an electric stove), it will be powered via a ridicolus plug at 120 V. The plug will overheat and a fire will start, in the standard US home built with wood.
When I was in Seattle 20 years ago, I noticed a lot of firetrucks passing by, a lot more than was usual in Europe.
My US friend said: it's normal, Christmas is coming...

That is just wrong!  I can't even imagine an oven or stovetop that isn't running on 240V.

stove, noun, "A heater, a closed apparatus to burn fuel for the warming of a room."

Not a great leap to realise he's not talking about your kitchen stove.

It never occurred to me to call a portable heater a stove.  Most of the portable heaters (also called space heaters) I have seen are on the order of 1.5 kW or about 12.5 Amps.  That is slightly more than a 15A breaker wants to provide on a full time basis.

Some come with 'tilt' switches to shut them down when they are turned over.

As to 'stove':
https://www.merriam-webster.com/dictionary/stove

Definition of stove (Entry 1 of 2)
1a: a portable or fixed apparatus that burns fuel or uses electricity to provide heat (as for cooking or heating)
b: a device that generates heat for special purposes (as for heating tools or heating air for a hot blast)
c: KILN

The stove is sometimes called a range but both terms are used in the US.  The term stovetop (one word) comes up when searching Home Depot:
https://www.homedepot.com/c/ab/types-of-stovetops/9ba683603be9fa5395fab90a04794ac

Ah, English, the US and the UK may both speak a language called "English" but there are substantial differences and context matters.

"Stove" in the USA is a kitchen stove, range, or what the UK would call a "hob". Except when it's not, "stove" also commonly refers to a wood stove which is a sort of fireplace used for heating rooms. You would never hear "stove" used to describe a portable space heater, which I've heard called an "electric fire" in the UK.

I believe the tilt cutout is a mandatory feature of portable heaters in the US, along with a thermal fuse. It was not always but it has been for decades.

I'm consistently surprised at the number of otherwise technical people in other parts of the world who are not aware that US homes have 240V despite the fact that our portable appliances and lighting are 120V.

[james_s]

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.
The new meters (the ones that allow for remote reading) are programmed for a maximum load of 3.3 kVA continous (in my case, with a 3.0 kVA contract) and it will trip if you drain more than the max for a long time (minutes?).
A contract with larger limits has higher costs.
I understand the US electric supply does not discourage customers from using a lot of energy (as long as they pay the bills), but in Europe a limited amouut of current to the users side allows for better planning of the network.

200A 240V is the standard service installed in the USA, I've seen 150 and even as small as 100A service in older houses but not anything built in the last 40 years.

Larger houses often have a 400A service with dual  panels. I've seen very large houses with a 600A service and three panels but that is not common.

[engrguy42]

Yeah, it's a bit of a surprise that, especially here in an "EE" forum people are surprised at how the electrical system in the US is configured. Geez, has nobody ever looked at that transformer on the pole in front of the house and wondered why the 3 wires are coming out? And nobody's ever opened up their main panel??

Anyway, it's only been like that freakin' FOREVER, so I guess I can understand the sudden revelation...

Regarding smart meters, yeah, there are some that can do what's called "DSM" (Demand Side Management) to curtail or shut people off, but as far as I know they haven't yet been widely adopted. Hell, some of us still have the old electromechanical spinning disk meters.

Anyway, the power company can just shut off the line serving your neighborhood anytime it wants, and that's probably by remote control (sending a signal over comm lines to the substation or an automated circuit opening device on the line serving your area), so not much difference. And they do that sometimes when bad stuff happens and have have to shut you off for some reason. Nothing new.

[tooki]

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.
The new meters (the ones that allow for remote reading) are programmed for a maximum load of 3.3 kVA continous (in my case, with a 3.0 kVA contract) and it will trip if you drain more than the max for a long time (minutes?).
A contract with larger limits has higher costs.
I understand the US electric supply does not discourage customers from using a lot of energy (as long as they pay the bills), but in Europe a limited amouut of current to the users side allows for better planning of the network.

LOL what? I live in a one bedroom apartment, and in my panel, I have 3x 13A circuits for outlets and lights, then 3x 13A for the washer, dryer, and dishwasher, and then 16A three-phase for the oven and stove (hob). And this is considered on the weak side by today’s standards here in Switzerland. (And this is in an apartment with central hot water and radiator heat, so not heated by my own electrical.)

[IanB]

So nobody has commented on his observation that 208 V provides 86.6% less power to heaters than 240 V? When in fact the ratio is 75%?

I would be bummed about that. 4500 W on the water heater at 240 V was reduced to 3380 W at 208 V.

I'm sure he meant to say 75% but somehow misspoke.

[NiHaoMike]

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

Modern heat pump dryers are pretty efficient, some even run on a normal 120V circuit.

So nobody has commented on his observation that 208 V provides 86.6% less power to heaters than 240 V? When in fact the ratio is 75%?

I would be bummed about that. 4500 W on the water heater at 240 V was reduced to 3380 W at 208 V.

I'm sure he meant to say 75% but somehow misspoke.

The "2/3" 120/208V system is common in apartments and condos in densely populated cities. There, heating appliances running cooler keeps apartment owners happy by reducing maintenance costs.

[james_s]

So nobody has commented on his observation that 208 V provides 86.6% less power to heaters than 240 V? When in fact the ratio is 75%?

I would be bummed about that. 4500 W on the water heater at 240 V was reduced to 3380 W at 208 V.

I'm sure he meant to say 75% but somehow misspoke.

You can get 208V water heaters and room heaters, I don't know how often they actually get used in those applications but they are available. 208V is pretty much universal in larger apartment buildings, they're fed with 3 phase with 2 phases to each unit.

[Bud]

If you are in the US and  you have an heater in a room, (e-g- an electric stove), it will be powered via a ridicolus plug at 120 V.

It is a 2 phase 240v plug. Typically used by electric dryers and kitchen stoves.

[TimFox]

Just to clarify language usage in the US:
The typical appliance found in the kitchen for heating food is called a "range", and can be either electrical or gas-powered.  The usual range has a cooktop above an oven, possibly with a second oven mounted above the cooktop.  Here is a good discussion of options and fuels, along with the required electrical connections:  https://www.abt.com/learn/kitchen-range-buying-guide
In informal usage, this is sometimes called a "stove" or "cook stove", but it is rare in US usage to refer to a space-heating appliance as a stove.
The plug required for a 240V range or clothes dryer is large: the older style has only three prongs, but the newer ones have four prongs (NEMA 14-30).  A typical electric dryer pulls 30 A at 240 V.
An historical note:  the "Franklin stove", see  https://www.ushistory.org/franklin/science/stove.htm  , was an American invention (Benjamin Franklin, 1742) for space heating to improve efficiency over a traditional fireplace.

[themadhippy]

And in the uk
Range = somewhere cowboys  live or chavs shop
cooker = thing for cooking food with ovens. heating rings and maybe a grill
stove = can be a  heater or a cooker  if your posh,but more common  to break or smash, ,as in " I'll stove yer head in"

[filssavi]

Just as an addendum, 3kW single phase in italy is just the standard contract, the utility will happily give you more, if you ask.

Normal homes usually have a single phase system,  in that cases to avoid unbalances you can ask for up to 6 kW (each kW over the standard will cost 20-40€ more each month).
You can also ask to have a three phase feed, for which there are no additional costs, in that case you can usually have a lot more power (up to 100kW over which you have to connect to the medium voltage grid),

You are allowed to draw up to 10% more indefinitely, while for higher draws over the meter will trip.

So the low size of electric feeds has more to do with how the people use electricity than anything else. Mainly we don't need that much electrical power, clothes are usually air dried (dryers are getting more common but just barely), heating and cooking is done with natural gas. the houses are small enough that a 1/1.5kw A/C system is enough. etc.

I think things will start to change probably when electric cars will get more common.

[TimFox]

From the past participle of "stave", the verb "stove" means "to break in a stave or staves of (a cask or barrel) so as to release the wine, liquor, or other contents", and the mid-19th century stories of whaling referred to ships "stove in" by whales.  The generalization to heads is straightforward.
Yes, cowboys have a "home on the range (noun)", but what, pray tell, do you mean by "chavs shop"?

[IanB]

To add to the British perspective, a stove is generally a fixed device in which you burn wood or coal, for heating or cooking. If for heating it is usually qualified, as for example "a wood-burning stove". If the word "stove" is used by itself, it would usually be understood as a cooker, and a "stove-top" would be where you cook with pots and pans.

Under no circumstances would stove be used to describe an electric, gas or kerosene fueled space heater. Such a thing would simply be called a heater.

[richard.cs]

I imagine a 120 V unit would incinerate its heating element on 230 V.

It might survive better than you expect, a 240 V one wired wired between phases (so 415 V) seemed to work just fine, just boiled 3x quicker. 

200A 240V is the standard service installed in the USA, I've seen 150 and even as small as 100A service in older houses but not anything built in the last 40 years.

UK typical is 60-100 A, single phase, 230 V nominal, over 100 A you generally have to go to three phase but it is not common domestically.

[duak]

Good point Richard - root 3 times the voltage is 3X the power so 1/3 of the time.  240 V is about double 120 V so we're looking at 4X the power and 1/4 of the time - providing the delta T between the element and water doesn't get too excessive.

Apparently Lao Tzu said "the light that burns twice as bright burns half as long".  I expect 4X the power would reduce life by a greater factor.

History corner?: I  sort of understand why North America has a lower nominal line voltage of 110 to 120 V is due to the Current Wars.  Edison was into DC and Westinghouse and others were AC.  Somewhere along the way it was legislated (although lifted later) to limit AC.   A recent movie was based on it: https://en.wikipedia.org/wiki/The_Current_War   I don't think Europe went into the DC dead end.  Now can someone explain Japan's 100 V at 50 or 60 Hz?

Cheers,

[Gregg]

The North American standard of 120V line to a grounded neutral may have been deemed safer in the days of knob and tube wiring. 
Over a hundred years ago electricity in the home was mostly used for lighting and electric lights although crappy by our standards were far safer than gas lights.  A common wiring method was to run the hot line across the uninsulated attic staying off the wood about an inch by the ceramic ‘knob’ insulators. The wire had minimal insulation often rubber with a cloth cover and were routed through wood via ceramic tubes. Splices were in open air, sometimes soldered, sometimes just twisted together and covered with friction tape maybe with a layer of rubber tape if you had the premium installation.  A tap off the hot line was run through the ceiling to light fixtures and another wire routed down to the light switch on the wall where it switched to the neutral which was often located in the basement.  Outlets were wired similarly hot from the attic and neutral to the basement. 
Early services were often 30 amp 120 volt with two screw in fuses that could easily be bypassed with a coin.  The wire was often 14 ga powered via a 20 or 30 amp fuse because it was rated for free air to help dissipate heat.
Standards back then were minimal at best and many ways were found to make this system far less safe.   Things like blown in insulation, kitchen appliances, Christmas tree lights and electric heaters could easily over tax the system.  It wasn’t uncommon to have a homeowner install an outlet and run the neutral to a water pipe instead of the actual neutral wire.

[james_s]

Another factor that likely contributed to the voltage choice is that 120V incandescent lamps are substantially more efficient than 240V incandescent lamps. The lower the voltage, the shorter and thicker the filament is for the same wattage. A shorter, thicker filament has lower convective losses. A 240V 60W bulb is only slightly brighter than a 40W 120V bulb.

[richard.cs]

Another factor that likely contributed to the voltage choice is that 120V incandescent lamps are substantially more efficient than 240V incandescent lamps. The lower the voltage, the shorter and thicker the filament is for the same wattage. A shorter, thicker filament has lower convective losses. A 240V 60W bulb is only slightly brighter than a 40W 120V bulb.

Well, were more efficient, prior to the invention of the "coiled coil" filament in the 1910s. It's just a way of making a long thin filament behave convectively as a short fat one.

[rstofer]

The "2/3" 120/208V system is common in apartments and condos in densely populated cities. There, heating appliances running cooler keeps apartment owners happy by reducing maintenance costs.

120/208V 3 Phase 4 Wire is quite common for industrial and commercial applications.  Obviously, it is used for all small receptacle loads in both applications since the voltage between neutral and any of the 3 phases is 120V.
277/480V 3 Phase 4 Wire is the other common industrial supply and most large commercial and industrial lighting runs on 277V and the motors run on 480V.  Industrial applications will have both 120/208 3 Phase and 277/480V 3 Phase distributed internally.  The utility will provide just the 277/480V and the owners will use small transformers to create 120/208V 3 Phase where necessary.
120/240V 3 Phase 4 Wire is an oddball configuration (called 'wildcat' by some) where one transformer is the common 120/240V single phase and the second transformer provides the other 240V leg.  Between the neutral and the 2d transformer output is 208V and this leg is never used for a non-3 Phase application.  This is known as an open delta arrangement.  It requires only 2 transformers so the utility tends to like it but the 240V 3 Phase is a little low for larger motors.  The transformer delivering 120/240 single phase will be larger than the transformer providing just the 3rd phase for motor loads.

None of these 3 phase configurations are delivered to residential occupancies, as far as I know.  Those are strictly 120/240V Single Phase.

We have all kinds of transformer schemes.  For 3 phase transformers, the secondary can be either wye or delta connected.  Loads are usually delta connected and have no use for the neutral.  The neutral is always grounded, sometimes solidly, some times with a resistor.  These resistor grounded systems exist to limit fault current, most typically for large motor installations. 

In thinking about it, it's a real mess!

[richard.cs]

120/208V 3 Phase 4 Wire
277/480V 3 Phase 4 Wire
120/240V 3 Phase 4 Wire
120/240V Single Phase.

In thinking about it, it's a real mess!

There are too many different voltages, and too many of them are too similar to really be useful, e.g. 208/240/277 are all too similar to have significant advantage, but are different enough to be incompatible for many types of equipment.

[tom66]

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.

[richard.cs]

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.

And the expected average for a house without electrical heating is 2 kW, this is the assumption used for network design. The UK approach with fewer larger transformers compared to the North American one does allow designing more for the average because there are more customers per transformer, but you still have to get that average right.

[GlennSprigg]

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...