why is the US not Metric

[Rerouter]

More marketing departments seem terrified of decimal points, leading to them using what ever unit gets there point across, e.g. if they want it to sound really big, or really small, either way you end up needing roughly 3 significant digits to actually know what to expect.

That and really stupid research that shows certain regions are biased towards lower economy numbers "Because that means less fuel is used" until they spend a few seconds actively thinking about it

Personally prefer L/100km for the work I do, because I have seen the above effect first hand far too many times,

They want there trucks to burn less fuel, not travel further, Yes I know what I said, and I have given up hope of winning that argument.

[vad]

Have you looked into the cost of 10AWG wire or calculated the losses you'd end up with?

Yes, I did few messages above. I’ll spare you from searching.

1.5V voltage drop (11% power loss at 12V at receptacle, 6% power loss with 24V at receptacle). And that’s at maximum load at furthest distance. I doubt AC-DC converter in a typical A19 LED bulb has near that efficiency.

250ft roll of 10/2 Romex is $130 at the nearest Home Depot. 12/2 is $60, 14/2 is $40.  You need 3 rolls to wire 10 branches in a typical single family house.

Voltage conversion is cheap and efficient now so it can be done at the point of use when needed. Less copper, lower losses, lower cost, there are lots of advantages. But not really enough to change it at this point, 120V works fine.

More electronic waste.

[vad]

litres per 100km alwoys confused me. I mean why?

I am more confused by MPG-e ratings of EVs that don’t have petrol tank.

[Monkeh]

Have you looked into the cost of 10AWG wire or calculated the losses you'd end up with?

Yes, I did few messages above. I’ll spare you from searching.

1.5V voltage drop (11% power loss at 12V at receptacle, 6% power loss with 24V at receptacle). And that’s at maximum load at furthest distance. I doubt AC-DC converter in a typical A19 LED bulb has near that efficiency.

250ft roll of 10/2 Romex is $130 at the nearest Home Depot. 12/2 is $60, 14/2 is $40.  You need 3 rolls to wire 10 branches in a typical single family house.

Or you could use a tiny fraction of the copper, existing hardware, and have greater flexibility and no single point of failure for all your lighting, and probably still come out on top on efficiency.. Even if you do fall slightly behind, substantially less copper used, no single point of failure, no DC rated switching arrangements, no separation of ELV and LV wiring needed. Oh, and you won't need terminations suited to ludicrously large wiring either.

[vad]

Have you looked into the cost of 10AWG wire or calculated the losses you'd end up with?

Yes, I did few messages above. I’ll spare you from searching.

1.5V voltage drop (11% power loss at 12V at receptacle, 6% power loss with 24V at receptacle). And that’s at maximum load at furthest distance. I doubt AC-DC converter in a typical A19 LED bulb has near that efficiency.

250ft roll of 10/2 Romex is $130 at the nearest Home Depot. 12/2 is $60, 14/2 is $40.  You need 3 rolls to wire 10 branches in a typical single family house.

Or you could use a tiny fraction of the copper, existing hardware, and have greater flexibility and no single point of failure for all your lighting, and probably still come out on top on efficiency..

Unfortunately, I still have to come across AC-powered A19 LED bulb that can work reliably in fully-enclosed or semi-enclosed luminaries (up to promised 25,000+ hours MTBF, without intermittent thermal shutdowns or bricking itself). And I still have to come across AC-powered A19 LED bulb that can dim properly.

[Monkeh]

Unfortunately, I still have to come across AC-powered A19 LED bulb that can work reliably in fully-enclosed or semi-enclosed luminaries (up to promised 25,000+ hours MTBF, without thermal intermittent shutdowns or bricking itself). And I still have to come across AC-powered A19 LED bulb that can dim properly.

I'll show you again for the hard of seeing:


It's tiny, it's SELV, it's efficient (okay I haven't measured it), it's cheap, it uses existing reasonably sized distribution, and it takes the LV stage out of your lamps. Sure, it's AC output, but you can do DC too - and active rectification will become cheap in a hurry if you want it to. I think we both know they'd end up needing to use bridge rectifiers to prevent wiring mistakes or unpolarised connectors being problematic anyway.

And of course, there are much better examples around which take discrete dimmer inputs and so forth.

[vad]

Unfortunately, I still have to come across AC-powered A19 LED bulb that can work reliably in fully-enclosed or semi-enclosed luminaries (up to promised 25,000+ hours MTBF, without thermal intermittent shutdowns or bricking itself). And I still have to come across AC-powered A19 LED bulb that can dim properly.

I'll show you again for the hard of seeing:


It's tiny, it's SELV, it's efficient (okay I haven't measured it), it's cheap, it uses existing reasonably sized distribution, and it takes the LV stage out of your lamps. Sure, it's AC output, but you can do DC too - and active rectification will become cheap in a hurry if you want it to. I think we both know they'd end up needing to use bridge rectifiers to prevent wiring mistakes or unpolarised connectors being problematic anyway.

I, personally, have three problems with this particular device: (1) it is not UL-listed, (2) my nearest Home Depot does not stock 12VAC operated A19 LEDs, (3) I doubt it will work properly with Lurton Caseta dimmers.

[wraper]

I, personally, have three problems with this particular device: (1) it is not UL-listed, (2) my nearest Home Depot does not stock 12VAC operated A19 LEDs, (3) I doubt it will work properly with Lurton Caseta dimmers.

No shit Sherlock. It's rated  for 230V AC therefore not for US market. And it's not a LED driver.

[Monkeh]

I, personally, have three problems with this particular device: (1) it is not UL-listed

It is quite amazing that products intended for sale in the UK and/or EU are not UL listed, yes. My point is the technology and products exist, and they've quite specifically not gone the route of relatively high current DC distribution around properties for the last 30 years for good reasons.

(2) my nearest Home Depot does not stock 12VAC operated A19 LEDs

Of course they don't, if they did people would put them in 120V outlets and things would explode. It should be readily apparent that you will require an appropriately non-interchangable fitting for such radically different supplies, whether you go the route of distributing them unreasonable distances or use local regulation..

(3) I doubt it will work properly with Lurton Caseta dimmers.

I'm not going to research how those operate to determine that. I rather doubt your proposal would either.

And it's not a LED driver.

Indeed, it's merely a stand-in for the basically identical constant-voltage DC, constant-current DC, and variable voltage or current dimming drivers, because I lack the patience to dug up specific examples of such for this guy.. Mind you, there's a multitude of 12V AC/DC operated LED lamps, dimmable and not, which are suitable for use with a supply such as this.

[wraper]

Indeed, it's merely a stand-in for the basically identical constant-voltage DC, constant-current DC, and variable voltage or current dimming drivers, because I lack the patience to dug up specific examples of such for this guy.. Mind you, there's a multitude of 12V AC/DC operated LED lamps, dimmable and not, which are suitable for use with a supply such as this.

It's drop in SMPS replacement for (usually toroidal) halogen lamp transformers.

[Monkeh]

Indeed, it's merely a stand-in for the basically identical constant-voltage DC, constant-current DC, and variable voltage or current dimming drivers, because I lack the patience to dug up specific examples of such for this guy.. Mind you, there's a multitude of 12V AC/DC operated LED lamps, dimmable and not, which are suitable for use with a supply such as this.

It's drop SMPS replacement for (usually toroidal) halogen lamp transformers.

Yes, I'm aware of that - I've used more than a few of them. It's the first thing I had a picture of to hand. It's quite suitable for supplying 12V LED lamps so long as they take AC (which they generally do).

[vad]

I, personally, have three problems with this particular device: (1) it is not UL-listed, (2) my nearest Home Depot does not stock 12VAC operated A19 LEDs, (3) I doubt it will work properly with Lurton Caseta dimmers.

No shit Sherlock. It's rated  for 230V AC therefore not for US market. And it's not a LED driver.

Thanks for letting me know before I ordered 50 of those. I was already pulling out credit card from the wallet.

[VK3DRB]

Besides the Altium grid lines "standard" being a dog's breakfast, many Chinese PCB manufacturers only specify their capability dimensions in imperial measurements (eg: minimum track width 7mils, rather than 0.18mm). This is only to appease US engineers who cannot fathom (sorry, 1.8288m) the metric system (Just kidding, sort of!).

One thing the Chinese government could do is force manufacturers to publish them in both metric and imperial, or better still, ban imperial measurements all together. They could do it very quickly .

Whereas if it were the British government it could take endless debates, several elections, a referendum, protests, resignations and billions of euros pounds over many years, and end up going nowhere .

[CatalinaWOW]

Besides the Altium grid lines "standard" being a dog's breakfast, many Chinese PCB manufacturers only specify their capability dimensions in imperial measurements (eg: minimum track width 7mils, rather than 0.18mm). This is only to appease US engineers who cannot fathom (sorry, 1.8288m) the metric system (Just kidding, sort of!).

One thing the Chinese government could do is force manufacturers to publish them in both metric and imperial, or better still, ban imperial measurements all together. They could do it very quickly .

Whereas if it were the British government it could take endless debates, several elections, a referendum, protests, resignations and billions of euros pounds over many years, and end up going nowhere .

Look at the bright side.  If they specified capabilities in metric it would probably be rounded to some nice number like 0.2 mm, so you gained 10%. 

[james_s]

Unfortunately, I still have to come across AC-powered A19 LED bulb that can work reliably in fully-enclosed or semi-enclosed luminaries (up to promised 25,000+ hours MTBF, without intermittent thermal shutdowns or bricking itself). And I still have to come across AC-powered A19 LED bulb that can dim properly.

I have lots of LEDs in fully enclosed and semi enclosed fixtures, some have been in dusk till dawn service since 2011. Philips and Ecosmart mostly. I did have some issues with the hall light which is fully enclosed, has two lamps and gets run many hours a day so I put some filament type LED bulbs in there and those have been fine, I think the ones I used there are Feit.

I can't say whether any will last the full 25,000 hours because even running ~12 hours a day since 2011 I'm not there yet but so far so good. The earlier Philips ones were actually rated for 50,000 hours.

Also noteworthy is the fact that the vast majority of the heat is from the LEDs themselves, not the driver.

[james_s]

Of course they don't, if they did people would put them in 120V outlets and things would explode. It should be readily apparent that you will require an appropriately non-interchangable fitting for such radically different supplies, whether you go the route of distributing them unreasonable distances or use local regulation..

Actually they do, well they're 12VDC.

https://www.homedepot.com/p/Feit-Electric-60-Watt-Equivalent-Warm-White-3000K-A19-LED-12-Volt-RV-Marine-Light-Bulb-BPA800-830-LED-12/301842502

The were once common in fancier RVs (caravans) and yachts that were equipped with some standard domestic light fixtures. They used to be incandescent of course and I've seen CFL versions as well. Now that inverters are so cheap and widespread I don't think you see them in new stuff but the bulbs are still readily available. Typically they are not located on the same shelves as all the ordinary light bulbs but most hardware stores will stock them.

Yes, if someone puts one in a 120V socket it instantly blows, but it's not really a hazard to anything but their wallet.

HID lamps are widely available that will physically fit into a standard domestic light socket as well, some of the lower wattage types will start from 120V without any assistance at which point they of course fail instantly, usually the molybdenum ribbons fail at the arc tube pinch seals. As with the RV bulbs, they rely on people having just a bit of knowledge beyond "hey I can stuff it in here".

[Monkeh]

Of course they don't, if they did people would put them in 120V outlets and things would explode. It should be readily apparent that you will require an appropriately non-interchangable fitting for such radically different supplies, whether you go the route of distributing them unreasonable distances or use local regulation..

Actually they do, well they're 12VDC.

Well, frankly, that's stupid.

Does not really happen here, with the exception of 110V lamps - but they're fairly restricted in availability.

E: Although it seems there's a handful of them making their way over from China thanks to your influence..

[james_s]

It's a complete non-issue, I don't think I've ever personally known anyone who put an RV bulb into a household socket. I'm sure someone has done it somewhere but it's certainly not common. They say 12V right on the bulbs, they're significantly more expensive than standard bulbs and while they are fairly widely available you kind of have to go out of your way to get them. If you do give a 12V bulb 120V it just blows out, pop, no drama or excitement. I put a 6V cadelabra base lamp in a 120V socket once when I was a kid, blew it instantly but didn't cause any harm beyond that.

It's not just the US that uses 120V, there are a whole handful of countries:
https://www.school-for-champions.com/science/ac_world_volt_freq_list.htm

[Simon]

litres per 100km alwoys confused me. I mean why?

I am more confused by MPG-e ratings of EVs that don’t have petrol tank.

It's to try and help the stupid people that are not very good as basic arithmetic.

[Rerouter]

The best way I have found to compare an EV to a Petrol/diesel is to look at the equivalent cost of power for the distance, then work out how much fuel you could buy on average for that cost.

Of the 6 EV buses I've worked with, they averaged about 17L/100 vs a similar size and style diesel at 31L/100, and as power gets more expensive, that gets closer to parity,

[Simon]

Yes but the average person cannot just look up wikipedia and find out the power density of petrol and calculate tho W/mile and compare it to the figures given for EV.

[Rerouter]

I did not say that... ok, example time.

Take a fancy Model S, Its a 85 KWh battery,
Its range is about 400 Km
And right here it costs 32c/KWh

.... $27.2 for 400 Km

Petrol here is about $1.30/L
so I could buy 20L for the same price

So 20L / 400Km
= 5L / 100Km equivalent,

I can buy a number of much cheaper cars that average about 6-6.5, So you don't save that much unless someone else is paying for the power.

[Simon]

Well veering off topic again but last time i worked it out with a economy 7 tarriff here in the UK at 8p/kWh I could run a car at break even price with petrol including battery lease if i did at least 7000 miles per anum. Petrol has risen in price since I did that calculation based on 250W/mile.

My current tarif mirrors wholesale prices and i can charge even less than 8p/kWh most of the time at night:

00:00 - 00:30    6.30 p/kWh
00:30 - 01:00    4.20 p/kWh
01:00 - 01:30    4.20 p/kWh
01:30 - 01:00    5.80 p/kWh
01:00 - 01:30    5.86 p/kWh
01:30 - 02:00    3.76 p/kWh
02:00 - 02:30    5.46 p/kWh
02:30 - 03:00    4.79 p/kWh
03:00 - 03:30    3.99 p/kWh
03:30 - 04:00    3.61 p/kWh
04:00 - 04:30    4.37 p/kWh
04:30 - 05:00    4.45 p/kWh
05:00 - 05:30    5.21 p/kWh
05:30 - 06:00    6.30 p/kWh
06:00 - 06:30    6.30 p/kWh
06:30 - 07:00    7.14 p/kWh
07:00 - 07:30    5.57 p/kWh
07:30 - 08:00    6.72 p/kWh
08:00 - 08:30    4.47 p/kWh
08:30 - 09:00    6.72 p/kWh
09:00 - 09:30    6.30 p/kWh
09:30 - 10:00    6.09 p/kWh
10:00 - 10:30    6.30 p/kWh
10:30 - 11:00    6.30 p/kWh
11:00 - 11:30    7.14 p/kWh
11:30 - 12:00    7.14 p/kWh
12:00 - 12:30    6.30 p/kWh
12:30 - 13:00    6.93 p/kWh
13:00 - 13:30    6.05 p/kWh
13:30 - 14:00    6.72 p/kWh
14:00 - 14:30    5.59 p/kWh
14:30 - 15:00    4.41 p/kWh
15:00 - 15:30    3.57 p/kWh
15:30 - 16:00    5.88 p/kWh
16:00 - 16:30    21.84 p/kWh
16:30 - 17:00    23.31 p/kWh
17:00 - 17:30    27.30 p/kWh
17:30 - 18:00    27.41 p/kWh
18:00 - 18:30    26.46 p/kWh
18:30 - 19:00    26.46 p/kWh
19:00 - 19:30    9.32 p/kWh
19:30 - 20:00    8.40 p/kWh
20:00 - 20:30    7.92 p/kWh
20:30 - 21:00    6.30 p/kWh
21:00 - 21:30    8.40 p/kWh
21:30 - 22:00    6.30 p/kWh
22:00 - 22:30    7.98 p/kWh
22:30 - 23:00    7.14 p/kWh

[boffin]

litres per 100km alwoys confused me. I mean why?

I am more confused by MPG-e ratings of EVs that don’t have petrol tank.

Exactly why /100km makes more sense.  Much easier to compare
7litres / 100km  against  17kWh / 100km (Golf v eGolf for example). 

You can more directly understand the difference.

[Simon]

Yes but it's more difficult to calculate what is required of a certain journey which is why it is stupid. So i am going to drive 15m, how much fuel/electricity do I need? the first thing you will do either directly or indirectly is to reverse it to fuel/power per mile or km