Bobbo wrote:
Why does the US/Canada do it differently than the rest of the world? Because, we can. It would have been just as easy to only use 240v here, then you wouldn't have, or need, two legs.
Mostly an historical issue. North America got the first grids and the local delivery portion tended to be a lot of focus on lights. That didn't take a ton of power and if you had low voltage, the lights still worked (just a little dimmer).
By the time they realized that they needed more power, it was going to be very expensive to upgrade everything to 240v. Instead, they did smaller incremental voltage increases. That's why you will hear people talking about 110v, 115v and 120v.
Since other parts of the world developed their grids later, they jumped straight to a higher voltage...but don't think it's all perfect and consistent, they still have issues going from country to country.
As far as the RV, it's pretty much identical to a typical household system except only 50amp @240v rather than 100-400amp @ 240v.
The fundamental issue driving the voltage is amperage per cable. The more amps, the bigger the cable required. By splitting out the loads, you can keep the cables manageable (though people already complain about 50amp cords). If you jump that up to 75-100amps, the cables become drastically larger.
- 30amp cords are typically 10 gauge (2.59mm diameter -5.26mm2 area)
- 50amp cords are typically 6 guage (4.11mm diamter - 13.29mm2 area)
- theoretically to run 100amp, you would want to jump up to something like a 3 gauge (5.83mm diamter - 26.65mm2 area)
As you can see the cables get really thick as the amperage goes up and it's not just your extension cord but the cables throughout the park.
50amp campsites only became common in the last 20-30yrs, so the issue of higher demand was already known. If you are putting in 50amp-120v, it costs next to nothing to jump up to 50amp-240v (mostly just a small increase in cost for the extra copper in the cabling), so it made a lot of sense to jump straight to the higher voltage system.
And if you look, the newest biggest rigs often have 3 air/con units, electric stoves, and a host of other electrical devices. 3 air/con units can draw 40amp @ 120v continous, so it would be marginal to handle the startup load on the 3rd air/con with the other 2 already running...let alone anything else. By splitting out the loads across both legs, it works a lot better.
