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Re: [TowerTalk] Power Distribution

Subject: Re: [TowerTalk] Power Distribution
From: jimlux <>
Date: Sun, 08 Aug 2010 07:43:51 -0700
List-post: <">>
Milan Dlabač wrote:
> OK Jim,
> But let me tell You, that most of family houses in Europe (even in Czech
> rep.) - probably more than 90% of family houses have 3 - phase  power system
> as normal way.Peak input power of my house is around 20 kW - including heat
> pump, washer, dryier, el.stove, ham radio  and etc. and still we have input
> circuit breaker 3x32A.I thing, that this is normal modern way how to do it.I
> can not imagine 200A input circuit breaker .Your system is older and I
> understand, that rebuilding could be quite expansive.

I think that it's "compatibility with existing infrastructure" that 
drives single phase residential use here in the US more than anything. 
It would be interesting to see the history of residential 
electrification in Europe, particularly the differences between the 
1910-1920 era and 1945-1960.  In the US, there was a huge build out of 
electrical distribution in the 1930s (depression era public works 
projects, Rural Electrification Administration, etc.), most of which is 
still in use  (it causes problems when it gets hot in the summer here.. 
all those 60+ year old transformers up on power poles finally dying)

As for the standard "200A service".. that's about 48kW, but nobody draws 
that much for very long. It was chosen more as a "nice round number" I 
suspect.  Yours is about half that.. 100 Amp service here would be 
comparable and there are quite a few residences with that level of 
service (or smaller, say in condominiums or apartments.. multi-unit 
dwellings in general)

Houses in the US tend to be larger than Europe, and we are fairly 
profligate with our electricity consumption to boot (having had and 
still having very cheap electricity on a per kWh basis).

The other thing is that the *installation cost* difference between a 
100Amp and 200Amp service is negligible.. the size of the feeder from 
the transformer is roughly the same, etc.

The transformers are certainly not sized for N-houses * 48kW/house.  My 
house has a 200 Amp service, but there are 8 houses on a single 50kVA 
transformer. Clearly they are not expecting us all to draw the max at 
the same time. As it happens our transformer is undersized, so we get 
light blink when the neighbor's AC turns on, etc.


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