Thinking outside the box a bit I think there could be lots of applications for “long extension cords”. Especially when you consider how light and thin a cord could be when you use high voltage.
While annoying to route around trees and a bit of a hazard considering the possibility of running the cord over, using a corded electric lawn mower worked passably well for a small yard.
This is an application where I find the old tech does a better job: push mowers.
I recently replaced my mower with an old push mower [1], someone local restores them and sells them for a reasonable price (much less than anything new or even a petrol or electric second hand mower.
It works so well I wouldn't go back unless I had more than about 200 sqm to mow. Modern push mowers are junk and put me off in the past, but the older ones are much heavier and better built. They cut grass cleaner than a rotary mower which is supposedly better for the grass too.
They really really are in NZ at least. I saw some at Mitre10 the other day and they were pretty much all plastic, wtf?
Someone local to me as well buys second hand mowers and fixes em up, puts a better motor on etc. Works well - been a very long time since I've touched an old push mower though!
My old man runs a landscaping/gardening/mowing business so I grew up helping mow lawns etc and you're quite right they've just gotten so bad. We'd buy those commercial ones, and over the years they just got bigger, heavier and shittier - breaking all the time. Dad went back to using just basic older mowers and they work just as well.
You're correct that those old push mowers are better for the grass if you don't have the catcher on - which is the reason for some mowers having that "mulch" function (spitting cut up grass back out without a catcher).
yep, they are very light and maneuverable and not have a battery pack allows for more interesting designs. but I have run over the cord before. things went quiet for some reason.
Perhaps, my own yard is just on the cusp: one battery charge with a cordless mower gets me about 75% of the way there. One decent length extension cord gets it done in one go, and I'd much rather have it done at once rather than wait for a charge cycle.
> I think there could be lots of applications for “long extension cords”
Ok, now I'm wondering how much one can decrease the weight of a rocket if it starts plugged to some cable.
Any ISP gain at the beginning of the trip helps decreasing a lot of weight, but cables weight something too, and 1km or 2 of cable falling vertically is a hell of a hazard...
There are rather big excavators/shovels as used in mining operations, for large-volume material handling, that are powered by a tether. I guess they don't nimble around much but rather stay in roughly the same spot, filling trucks to haul the rocks away for smelting/processing.
They do this with large mining machinery such as the drag lines and bucket wheel wheel excavators. They don't move very far so extension cords are acceptable.
And in mining they run portable medium voltage wiring through the tunnels to baby substations. They even make plugs and sockets rated to 15kV or possibly to 35kV, the upper limit for "medium voltage" in NA.
Obviously you aren't going around plugging these cables in like they're attached to a reading lamp. They are on disconnects or circuit breakers and the circuit is de-energized before connection or disconnection. Otherwise arcing would destroy the connector. A faulted circuit would cause an explosion on connection likely killing or severely injuring an operator.
Electricians working on medium voltage circuits must have medium voltage training and certifications.
The limiting capacity of an extension cord is the resistance it can carry - at high resistance the cord will basically catch on fire. High voltage can deliver much more power at lower resistance as compared to low voltage. The easy example is household power -- in the US, standard household electricity is 120v, so a common 14 gauge wire that can carry 12A at constant load would be able to deliver 1400 watts. If you use 240v, that same wire can deliver 2800 watts.
To extend that to extension cords -- if your boat/tool or whatever needs 5kw of power, at household voltage of 120v, you'd need a #4 wire which weighs 1.3 lbs/10 ft. At 240V, you'd need a #10 wire which weighs 0.3 lbs/10 ft. At 360v, only a #14 wire which weighs 0.13 lbs/10 ft.
So by tripling the voltage, you can cut down the weight of the cable by roughly 10x.
