On 9/20/2013 1:53 PM, Bill Turner wrote:
ORIGINAL MESSAGE: (may be snipped)
On Fri, 20 Sep 2013 11:42:04 +0200, Peter wrote:
Bill,
The supply is a neutral (which is theoretically at ground potential and actually may be
so, or very close to it) and a single phase 240volt line - in my case 234, as it happens.
The neutral is the centre point of the star connected (wye connected) sub-station
transformer secondary, is grounded at the transformer and various places along its run.
That run maybe in older installations a lead sheathed or steel wire armoured cable, with
red yellow and blue phases on it, and in newer installations can be aluminium sheathed.
The sheath or the armouring can be the neutral or there may be a neutral wire as well.
Each house gets a tap of neutral and one phase, so house 1 gets red phase, house 2 gets
yellow phase, house 3 gets blue phase and they all get the neutral. By using the
aluminium sheath as neutral, "advantage may be taken of higher technology
cable" i.e. cheaper!
73
Peter G3RZP
REPLY:
Ok I think I understand. It sounds like the system we used many years ago
before 240 V service to houses became common.
Nearly 70 years ago, here in Lower Michigan, our old farm house had the
same feed we have now except the voltage was 220 instead of 240 nominal
and maybe a 30 A service with screw in fuse blocks following a pair of
cartridge fuses about 4 or 5" long by roughly 5/8" dia all on a board.
The house was fed with a center tapped 220, plus neutral for 110 each
side. There was no fuse panel as we think of them. Most of the outlets
were 2 wire. Half the house still had knob and tube with fabric
insulation.<:-)) But we did have 110-0-110 for a 220 feed. It was
still a nominal 110-0-110 into the late 70s. Kitchen range was 3 #6
feeding 220. I'm not sure when they went to 230 and 240, but it is 240
at present and AFAIK it's been 240 since we moved here in 84, 29 years ago.
73
Roger (K8RI)
In the early days each house
got only a hot and neutral or hot and neutral plus ground but it was only
120 V instead of 240, of course. Purists will point out that way back, the
standard here was 110 V, then it was upped to 115, then 117 and now 120.
Those numbers may not have been universal across the US, but that's what we
had where I lived in Southern California.
As a historical note, if you go way, way back in some areas we had 50 cycle
instead of 60 cycle. I remember my parents saying when the change was made
they had to take their clocks in to have the motors changed. That was in
Iowa back in the '30s.
Also, we typically don't have three phase in residential areas, or at least
not in any areas I have ever lived in. Three phase is commonly used for long
distance HV transmission lines and industrial areas.
Thanks for the info.
73, Bill W6WRT
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