| Of course most "Edison" socket lamps like to have the base which
| occasionally can come in contact with the users skin connected to the
| neutral conductor.
We need to get rid of those. I know, maybe we can ban light bulbs :-)
|> Consider a 240/139 volt star/wye system. The center is grounded. All
|> are 240 volts. All breakers will be 2-pole. All switches will be 2-pole.
|> The insulation systems can assume no voltage is more than 139 volts above
|> ground reference (as the nominal reference value).
| Well, most folks would "consider" this to be a PITA.
I consider the added cost of larger/more branch circuit conductors to be
|> Now consider grounding that system at one end instead of the center. What
|> changes? The voltage relative to ground changes. Now the highest is 240
|> instead of 139. It will cost a bit more to insulate for that. But 2/3 of
|> the loads will have a grounded conductor. Breakers and switches can be of
|> the single pole type for these only. Of course this can make for
|> and/or imbalance. It's also about the same as corner grounded delta.
| It's not the insulation (which is typically good for 600 volts) but the risk
| of death or serious injury if some poor idiot ends up getting shocked.
| That said, the air handler in our home is designed for 240 volt operation
| and has a warning that no conductor can be over 150 volts from ground. So
| my HVAC system would be perfectly happy with your 139?/240 system.
And about everything else designed that way could be happy. And most of
the appliances used in Germany would work, given they cannot depend on
one conductor or the other always being the grounded one given the Schuko
is not polarized.
|> In single phase, those 240 volt loads would be supplied with each end of a
|> 240/120 Edison style split just like we have now in North American. If we
|> only had 240 volt single phase utilization everywhere like this, we could
|> supply these loads with either 240/120 single phase or 240/139 three phase
|> I'd rather have the grounding at the center of the system so I can keep
|> system in balance with like loads all around. But my point is, there is
|> fundamental _electrical_ reason we can't have an unbalanced relative to
|> system design. There are good _costs_ reasons to avoid that.
|> And for the most part we also have line-to-grounded-conductor utilization
|> which can be powered in North America by either 240/120 single phase or by
|> 208/120 three phase systems.
| The 120/208 system is downright silly. If local distribution MUST be 3
| phase, it might make sense to have a 7 wire system with the 3 phases on 3
| separate 120/240 system. Folks who NEED 3 phase can get 120/208 AND
| 120/240 with 2 extra wires.
If I had a home so large that it needed so much power that I had to have
three phase, that would be the way I would want to go. But it might be
done by having 480/277 coming in and 3 gray humming boxes in the electrical
room (a house that big means electrical gets its own room). Of course if
I had that, I'd want to use that 480 somewhere :-)
Likewise, if I build an apartment building bigh enough to require three
phase, I'd want that to supply each apartment with genuine 120/240.
I had previously posted my preference for line-to-line systems so we can
use the higher voltage across the build to avoid crazy voltage mixes between
single phase and three phase systems, while keeping line-to-ground lower
for reduced shock risk in the mode most humans get zapped. I had also
proposed that if I got to go back in time and decide the system, I'd have
chosen to go with 288 volts line-to-line for everything, which could be
had with 144 volts on single phase and 166 volts on three phase.
|> Still, I would prefer a line-to-line system (always center grounded,
|> because of the reduced copper wiring requirements, and the decreased power
|> lossage, of the higher voltage that can be had at a lower relative ground
| The "service" conductors are almost all Al today. Inside the building most
| electricians perfer sticking to Cu with the possible excepts of stove, water
| heater, and HVAC circuits.
The service conductors are mostly irrelevant. With a 120/240 system, the
loads will be "mostly" in near balance, and the effect on the conductors is
equivalent to 240 volt loads.
It's the branch circuit conductors I'm concerned with. There are a lot of
them and they tend to have more amps on them in the 120 volt parts of the
| Cu is dirt cheap compared to Cu.
| But the cost (including panel capacity) of 2 pole breakers for all loads is
| a "deal breaker."
Is it? Compared to the cost of wiring the circuit?
With a 240 volt circuit, you can put more on it. That means fewer circuits.
So you can approach maybe half as many circuits. So the total number of
circuit breaker poles would be only slightly increased, not doubled.
|>While breaker costs and switch costs are higher due to the 2-pole
|> needs, the branch circuit wiring costs will be lower for a given voltage
|> relative to ground.
| Not compared to 120/240 basic service.
You can put a lot more watts on smaller wires with 240 volts, compared to
with 120 volts. So either you have circuits with smaller wires, or you
have fewer circuits, or some combination.
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