AIUI, out in the road there are three live wires and one neutral. The phase
s of the lives are 120 degrees out of phase with one another. The potential
difference between any two live wires is 440V. The potential difference be
tween any live and neutral is 230V. Domestic supplies only tap one live and
the neutral to give you a single phase supply, so if you want a 3 phase su
pply for a workshop or whatever, you have to get the leccy blokes in to dig
up the road and tap you into one of the other live wires. Do I have that r
Oh, and before some helpful soul offers up a practical solution, such as "g
et yerself a phase converter, mate, it's a lot cheaper" I should just point
out that I'm NOT looking for solutions, here, I'm simply enquiring as to w
hether my understanding of the basic situation is correct or not. Thanks!
On Sunday, 7 July 2013 15:08:12 UTC+2, Archibald wrote:
"get yerself a phase converter, mate, it's a lot cheaper" I should just po
int out that I'm NOT looking for solutions, here, I'm simply enquiring as t
o whether my understanding of the basic situation is correct or not. Thanks
Er, technical and theoretical. I'm already aware that the most cost-effecti
ve practical solution is to hook up a phase converter to the distribution b
oard via its own spur and that's what I'll probably end up doing.
I don't really see any 'legal' angle provided the leecy board or their
agents does the work.
In addition to the cabling, you will need a change of meter and
I doubt that they will want to balance the loads for domestic use so
your main house load can stay on one phase and the three phase go off to
your workshop etc
When selecting your wiring to the 3 phase load, you may want to run a
neutral as well because some machines use the neutral for control
circuits. Latest machines tend to use a 440-110 or a 440-24 transformer
for controls. If you are buying secondhand stuff, my suggestion would be
to be prepared with a neutral too.
Incidentally if you go down either the converter or inverter route, you
might find this of interest.
Some converters will use the single phase neutral as one of the output
phases thus not providing a neutral in the correct relationship to the
Inverters will usually only provide 3 phase output at the same voltage
as the input. i.e. run from 240v single phase will only produce 240v
three phase output so motors in your machines need to be dual voltage -
marked as 240/440v or similar.
It's curious. I've been heavily into electronics for decades yet nothing I'
ve learned it seems, is relevant to domestic/industrial electric installati
Though I'm intimately acquainted with the concept of phase, phase-shift and
know the difference between current, voltage and power inside-out I'm stil
l struggling to get to grips with this 'macro' stuff. These two fields are
like chalk and cheese. I suppose an electrician would be equally perplexed
if required to calculate the output impedance of a buffer/current-amplifier
I mean they're clearly two different disciples entirely. In my typically mi
llivolt/milliamp world, we don't have to contend with forces sufficient to
rip a machine's internals to pieces as you do with power engineering, so th
e need for nice, smooth 3 phase supplies simply doesn't arise in the first
I've found that most sparks I talk to don't have an in depth
understanding of the subject. They are taught largely by rote both in
college and as apprentices. They know all the how but very little why.
There are exceptions naturally.
My background like yours is in electronics but I've learned to adapt
over the years.
On Sunday, 7 July 2013 18:58:22 UTC+2, Bob Minchin wrote:
y millivolt/milliamp world, we don't have to contend with forces sufficient
to rip a machine's internals to pieces as you do with power engineering, s
o the need for nice, smooth 3 phase supplies simply doesn't arise in the fi
I think you may be right. A recently qualified young electrician told me, i
n regards to electrical safety, that "even just a few megaohms can kill you
." I shuddered at the time, but feel much less alarmed now in the light of
On Sunday, 7 July 2013 20:05:34 UTC+1, firstname.lastname@example.org wrote:
lly millivolt/milliamp world, we don't have to contend with forces sufficie
nt to rip a machine's internals to pieces as you do with power engineering,
so the need for nice, smooth 3 phase supplies simply doesn't arise in the
in regards to electrical safety, that "even just a few megaohms can kill y
ou." I shuddered at the time, but feel much less alarmed now in the light o
f your remarks.
Aren't megaohms poisonous just like snakes ;-)
On 07/07/2013 15:32, email@example.com wrote:
I found doing a bit of software development work on high power HF
amplifiers / transmitters was quite enlightening in that respect... It
certainly changes ones TTL/5V view of the world, when dealing with 10kV
step up transformers!
On Sun, 7 Jul 2013 05:59:03 -0700 (PDT), firstname.lastname@example.org
No good tapping into just one of the other live wires you need two
Five wires in total
Plus a new three phase meter (or another two single phase ones)
and a big hole in your bank account
Not entirely sure, but when they replaced the main fuse and housing here
some years ago, I'm sure I remember seeing four cores (three phases +
neutral, with the sheath as earth). It could well be that they brought
3-phase to every house on the road when they were built in the 30s and
only connected one phase at each. If I were to need 3-phase, that'd be a
useful cost saving!
This house (built 1911) has all 3 phases incoming - I assume so proper
balance could be obtained empirically. When they built a new estate of 25
bungalows, just round the corner, some 30 years ago - they were all on the
same phase. How things change.
When I worked for an electricity board, it was more usually done
surreptitiously, in one case by cutting small holes through the wall and
driving six inch nails through the neighbour's meter tails, in order to
keep the electricity bill down.
The basic numbers in the UK are 415v 3Ph. 240v single phase = 240v from
any of the three phases, to neutral. 415v as measured from any phase
aay of the other two.
If you have 1ph + N, you are lacking two more phases to make a 3ph
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