[andrewla]

> The average lightning strike contains about 1 million joules, enough energy to fry the founding father in his boots. “The typical house in the U.S. has 100 amp service or about 28 horsepower,” says Kirtley.

Boy do I get frustrated when using compatible units without conversion. The unit that I hate more than any other unit in the universe is the KwH, which is dimensionally equivalent to the Joule, so I don't understand why we don't just use that instead.

"The typical house in the U.S. has 100 amp service or about 28 horsepower" -- seems that it would be way more interesting to say that "the typical house has 100 amp service at 120V, which means 12,000 J/s".

The way the original quote is phrased (and the introduction of horsepower of all things) seems insane to me; the clarification adds zero value. You still haven't addressed the main question, which is "is the energy in a lightning bolt a significant amount of energy compared to household usage". For all I know 28 horsepower is 1,000,000 J/s, so a lightning bolt would only power a house for a second.

EDIT: as many commenters have pointed out, apparently most houses get 240V service, so just double the number above. Still, this is easily fixable, and the main point is that horsepower does not add any value to this discussion.

[flyinghamster]

> 100 amp service at 120V

Strictly speaking, 240V. Normal electric service in North America is 240V split-phase, with the distribution transformer's center tap grounded and serving as the neutral line. We normally only use the full 240V for heavy loads like electric ovens, arc welders, large air conditioners, and such.

Large buildings often use 208V three-phase power, yielding 120V phase-to-neutral, and large commercial lighting installations are often 277V taken from one leg of a 480V three-phase feed. Voltages greater than 240 are not permitted in residential service, and I wouldn't be surprised if phase-to-neutral > 120 is out as well for homes.

[mepiethree]

Do you work in clean energy tech by any chance? Software people who know these things are like unicorns

[breakingcups]

There's probably a large overlap between software people and people who subscribe to Technology Connections: https://www.youtube.com/watch?v=jMmUoZh3Hq4

[trelane]

The residential side can be discovered if you're a DIY homeowner.

[jfim]

The kilowatt hour is a fantastic unit when talking about electrical consumption.

Are you running a 100W load (0.1kW) for an hour? That's 0.1kWh. Running it for ten would make a whole kilowatt hour.

This allows for easy calculations of how much something is going to cost in electricity, and the units are such that it's easy to do the math in your head.

[andrewla]

You're using a toy example to strawman the Joule counterpoint. How much do you use in a month, which is the typical billing cycle? Off-peak vs. on-peak cost?.

In the end there's no practical utility to this. We just pretend that we're living in a world where you get a 100W light bulb and know exactly what it will cost you, and not a world where half your bulbs claim to be 100W but are actually 14W with 100W-incandescent-equivalent and such.

[trelane]

> You're using a toy example to strawman the Joule counterpoint.

Not a toy example. That's exactly how I estimate energy consumption for off the shelf devices. And for battery life (W*h but still).

> 100W light bulb and know exactly what it will cost you, and not a world where half your bulbs claim to be 100W but are actually 14W with 100W-incandescent-equivalent and such.

If you've lived with lighting you're responsible for, you've replaced bulbs. You know the different technologies and the packages say how much power they require.

[MonkeyClub]

Same here, I find the KWh to be a very useful unit for daily calculations of that sort, where I want a quick upper bound on things to make estimations.

Last year I switched off my fully-functional 2008 workstation (a lovely Fujitsu Celsius W370 on OpenBSD, a furry joy) because of such an upper bound difference (300W vs 65W for the ThinkCentre that hides among the books on my desk's side).

This sort of works in a similar way with light bulbs as well. Although lumen would be the appropriate unit for luminosity, the packaging uses wattage to indicate luminosity.

Although lumens and Watts are correlated, they aren't dimensionally equivalent as Joules and Watts are (CMIIW).

That "100W" on the package an electrically 14W bulb simply means "it's only using 14W, but shines like a 100W bulb, go ahead, BOGOF".

[andrewla]

> 300W vs 65W

A watt to watt comparison is fine. Why hours? I can tell you right now that the big one uses ~4.5x the power. Is it really that much easier to convert the time you're using the device to seconds? If you're going to multiply by the electricity cost anyway, might as well break out the calculator one step early.

[trelane]

I use watt when I want to compare power, and watt*hour when dealing with energy. Hours because hours are a lot closer to the real spans of time I use, and therefore much easier to calculate with. E.g. it's more common to run a 3kW AC for 3h than 3s. So, 9 kWh instead of 9 kWs (or 180kWs, for the same time span)

> If you're going to multiply by the electricity cost anyway

I don't usually convert to money. If it's a linear cost per kWh, then I can deal with that at the end or, more likely, don't actually really care.

The _actual_ cost you pay is often tiered anyway, so who knows what the price _actually_ is until you have the whole month's worth of power usage finalized. And then it's not clear what I could account to what tier.

> might as well break out the calculator one step early.

Bold to assume I use a calculator much.

[MonkeyClub]

Yeah exactly, I didn't even need to take time into account, I was looking for the upper bound presuming it's always on with a simple Wattage comparison.

But that was mostly because that workstation, albeit lovely, had a very long boot process.

The ThinkCentre boots in under a minute, so I actually end up only booting it when needed.

(Some of my work can be done offline, and I jump at every opportunity to `halt -p` and be in the quiet offline space/state.)

[2Gkashmiri]

>In the end there's no practical utility to this. We just pretend that we're living in a world where you get a 100W light bulb and know exactly what it will cost you, and not a world where half your bulbs claim to be 100W but are actually 14W with 100W-incandescent-equivalent and such.

Where i live, the pricing is based on the amount of energy "consumed" during a month. plus we use 220v.

i use the kwh extensively, my induction cooker is rated at 1300Watts so i know by running it for 1 hour i am consuming 1.3kwh.

my monthly "consumption" before installing a 5kwh solar on-grid used to be around 300Kwh during summer months so over time i have learned to "reduce" my monthly usage, aka kwh by reducing my electric hot water geyser( going to solar water heater) (2kw geyser).

the kwh is definitely a good indicator for me

[jfim]

To take your example, your 14 Watt lightbulb would use about 0.35kWh per day if running all day, or about 10kWh per month of nonstop usage. At 0.15$/kWh, that's about a dollar and fifty cents, assuming you'd want to leave it on all day and night.

All of that math can be done in your head too, if you're willing to approximate the number of hours in a day to 25 and the numbers of days in a month to 30.

[andrewla]

I'll take one more shot at explaining why this continues to be a strawman.

Why would I be running the light all day? The assumptions being made here are unrealistic enough that the answer becomes meaningless. The realistic question here, "how much money would I save by switching from a 100W incandescent bulb to a 14W LED bulb" is not helped by any of this kWh nonsense.

[jfim]

Maybe your utility company bills in joules, but mine does in kWh. You can easily figure how many kilowatts your bulb does (divide by 1000), and you can come up with an estimate of how many hours you use it in a day/month/year, which is then easy to turn into an actual dollar amount.

A joule is just a watt second instead of a kilowatt hour, and the 3600 factor (seconds per hour) is really annoying to use in mental math.

[johnwalkr]

Hours are usually more convenient to work with than seconds when talking about energy use (even in this case when you are comparing to other things. Plus it's the de facto standard unit more people are familiar with. Power bills, electric car capacity, and energy efficiency are all normally described in kWh.

[andrewla]

This is true, but it is exactly what I am railing against. It's just tradition -- energy in houses is kWh, so let's use that for other things too.

Instead, let's just use Joules everywhere. Easy peasy. Why are my batteries rated in Ah -- it's not like they're providing a variable voltage source; just give me Joules.

I know this is a ridiculous hill to die on, but I will die on it!

[trelane]

> it's not like they're providing a variable voltage source; just give me Joules.

They are, technically. https://www.batterypowertips.com/how-to-read-battery-dischar...

Probably doesn't matter though. :)

[themitigating]

The typical house has 240 volt service in the US (two legs of 120v). I would also say a decent number of homes have 200amp as well

[csdvrx]

> The typical house has 240 volt service in the US (two legs of 120v).

Can we wire that in a way to would allow installing .uk or .de Schuko Type-F plugs?

It would be funny (and weird!) to have 220V available on a european socket for say a desktop equipped with a 1.5kW PSU for the upcoming Nvidia 4090 :)

[jeramey]

You’d probably need to do this with an AC-DC-AC transformer to also get the circuit converted to the 50hz cycle European power systems use, but it’d just be a waste because of the power losses involved (not to mention the expense of the transformers). Also, a typical 15A circuit in a home will handle ~1.8kw of sustained load, so as long as you can dedicate a circuit to such a rig, you’d be fine.

[garaetjjte]

Computer power supplies won't care about 50/60Hz difference (maybe except some slight efficiency change).

[ThePowerOfFuet]

Computer power supplies don't give a shit about frequency. They will happily accept 120/50 or 240/60.

[trelane]

There may be ordinances requiring a specific plug type, and I'm pretty sure the NEC has opinions on outlets. :)

That said, it's your house, so you may be able to do that in some places. I've thought about it myself, so I can get a euro tea kettle.

That said, the power will still be at 60Hz not 50, which will matter for some uses (e.g. impedances will change).

[AnotherGoodName]

You probably have a few such sockets around. Not the UK or eu form factor but 240v at least. Look at how your dryer or AC plugs into the wall and you'll see something different to the usual plugs.

[trelane]

These are all standardized and have meaning. https://www.electronicshub.org/electrical-outlet-types/

There are definitely 240V for higher power usage (because they will need half the current for the same power with double voltage, and current (current density, technically) is what causes joule heating and melts wires/ starts fires.

The sockets will be incompatible with Euro or UK sockets. You could change the socket to a euro socket, bit the frequencies will be wrong for euro or uk devices (60Hz in the us, 50 in europe & UK.) This may or may not be important depending on what you're hooking up to it (understand that impedance and other electrical things are a function of frequency). The safest option would be to get something to convert the power (there seen to be products to do that) and put _that_ behind the Euro or UK outlets.

[themitigating]

Maybe motors because you can replace the neutral (in eu) with a hot (us) and it's basically doing the same thing.

[yourapostasy]

A surprising (but still tiny) number of US houses also can have three-phase brought out to them by the electric utility. Some utilities will charge you upfront for stringing it up and lighting up the wires, but another surprising number of utilities will just amortize it from the monthly cost of service.

It's still rare enough you have to ask ahead of time if you want it for any building you get into, but in some major metro areas it has gone from "you have got to be joking" to "sure, let me check on that".

Now if only I can find a reliable, durable three-phase solar inverter...

[themitigating]

3 phase gets you 108v on each hot leg. Many items will specify 110v/120v . 108v is close enough

[samatman]

This is true, but I'm fairly certain that the amps of available power are calculated on a 120v basis, a 10 actual-amp washing machine would use 20 accounting amps at maximum power.

[sokoloff]

The rating of a service (and by extension, the main breaker) is available at 240V. It's true that if all of your 200A load is consumed on a single leg, with zero amps consumed on the opposing leg, that you would only be able to consume 200A * 120V nominal or 24kW, but if the load is balanced, you can pull 200A @ 240V nominal or 48kW.

[Schroedingersat]

> The unit that I hate more than any other unit in the universe is the KwH, which is dimensionally equivalent to the Joule, so I don't understand why we don't just use that instead.

kWh/yr is worse. It's just watts but obfuscated. Gets used for appliances.

[ravi-delia]

The KwH makes sense if you consider that while units are largely path-independent, mental calculations are not. At any given moment, the sensible measure of your house's electricity usage is in kW. And to work backwards to figure out consumption, the hour certainly beats the second. Sure, you could call it 3.6e6 joules, but at that what point what does it buy you?

Horsepower is clearly insane though, I have no idea why you'd bother.

[andrewla]

For most realistic conversations you'd be talking about the relative consumption of two devices. Watts/kW is totally fine for this.

Regardless, head-math or otherwise, the vast majority of people will never do this calculation at all, except maybe to weigh the relative power consumption. And if they do the math, having a calculator and having all the units be compatible with each other (so just a natural conversion of W to J/s) is totally fine.

[greenbit]

Idk, I think OP indicated that a typical lightning bolt would power a typical house (presumably at the stated nominal full load) for about 15 minutes. I.e., you'd need 4 strikes per hour, per hour. Now granted most houses won't run at peak load all the time, maybe you'd only need one strike per hour per house - but that's still clearly a lot more lightning than is generally seen.

[andrewla]

The article is short and such an indication should be easy to cite directly. If I missed it, please let me know.

As far as I can see, nowhere in the article does it give enough information (even if you take into account unit conversions) to say how much of a house's electricity would be supplied by a lightning bolt.

[samatman]

The kWh is of course exactly what you want if you're working with power over time.

Example: a 100 amp house circuit running maxed out in the US will use 12 kWh per hour, or 0.2 per minute. Try doing it in your head with joules. Annoying right?

12 kWh / h? Am I a crazy person? No. I'm working on a useful problem.

[csours]

I thought that quoting in horsepower was very interesting as many people are currently thinking about the load that EVs put on the grid.