General > General Technical Chat
The US electrical system
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:
--- Quote from: tom66 on June 26, 2020, 09:14:00 pm ---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.
--- End quote ---
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:
--- Quote from: james_s on June 27, 2020, 03:32:07 am ---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.
--- End quote ---
A heat pump makes a big difference there. Or even a heat recovery exchanger, for that matter.
cliffyk:
--- Quote from: james_s on June 27, 2020, 03:32:07 am ---
--- Quote from: tom66 on June 26, 2020, 09:14:00 pm ---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.
--- End quote ---
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.
--- End quote ---
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...
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version