Re: voltage question.....

On Nov 7, 2:13 pm, Jerry Avins <j...@xxxxxxxx> wrote:
Fully Half Baked wrote:
On Nov 7, 4:46 am, Jerry Avins <j...@xxxxxxxx> wrote:
Clearwater's wrote:
On Nov 6, 6:13 pm, Fully Half Baked <jfez...@xxxxxxxxxxxxxx> wrote:
......
The
problem with an earth rod is it's resistance depends on the type of
ground. If you live somewhere soggy you're ok but in the desert you
have problems.
Perhaps it is time to resurrect the old story (urban myth
or maybe a rural myth, or maybe it is just a shaggy
dog story after all) about the woman living on a
remote farmstead who said that her dog knew when
a telephone call was coming and would bark to alert
her about 10 to 15 seconds before the phone rang,
and would stop immediately after the phone rang.
But this happened only on sunny days; on rainy
days, the dog stayed indoors and was oblivious
to incoming telephone calls.
A skeptic at the phone company who didn't believe the
tale of the psychic dog investigated and found that the
the phone installer had used a ground rod as the return
wire and had not installed the rod properly.  Furthermore,
on sunny days, the dog was chained to the ground rod
with a metal chain.  When a telephone call came, the
ringer would not sound because the bad ground meant
that no current was flowing.  Thus, the entire ringing
voltage would be applied to the dog who would start
yelping in pain.  After a few seconds, the dog would
urinate, wetting the ground rod and reducing the
resistance considerably.  The phone would start
ringing, and the dog, no longer being subjected to
electrical shock, would quiet down.
Moral: Do not piss on ground rods of unknown provenance.
The phone in my country house had a four-party phone line, but I never
heard anyone else's ring. (I could hear any of the conversations if I
picked up my instrument.) The phone company used two ringing
frequencies, and the ringers were selective. That could account for two
private rings, but how did they do four? (Answer an a day or two.) There
was no 60 Hz hum in the talk circuit.

There are two conventions for carrying 220V overhead lines on private
poles. With one, the middle wire is the neutral. The other puts the
neutral wire (always grounded at each building) on top for a modicum of
lightning protection. A cousin, a licensed electrician, helped rewire
the place and grounded one of the hot phase at the sewage-pump shed. For
much of a summer, we got shocks from the kitchen faucet. Our power bills
seemed high. Finally, I borrowed a clip-on ammeter and measured four
amperes flowing in the pump-house ground rod. I never figured out why so
little.

Jerry
--
Engineering is the art of making what you want from things you can get..
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

I rekon it's because you have 220/4 = 55 ohms. If you had a fault
that's a dead short to earth it's not going to blow anything more than
a 4 amp fuse.

In a 220V 2-wire system, each wire carries 110V with respect to the
neutral. In the house, outlets are wired hot-to-neutral except for heavy
equipment. So yes, 4A implies 27.5 ohms. Direct measurement showed much
less. I suspect that weeks of current modified the ground path, which
reverted before I made that measurement.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

What country is that and what are you calling neutral? In the UK a
single phase supply is 230Vrms phase wire and neutral wire which is
connected to earth. Your supply can be either 2 or 3 wire because
neutral and earth can be either combined or separate but the end
result is still 230Vrms between phase and neutral.
.

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