Quick question for the electrical boffins:

AIUI mains voltage is now 230 volts -6% +10%. ie 216 to 253 - correct or
rubbish?

My question is how is it measured? I've stuck my AVO across the incomers to
the main fuse box, and can get the voltage down to about 216v if I switch on
about 6.5KWs of electrical load on the property - without any substantial
load the voltage is nearer 250V. So, under what load condition is the
voltage measured?

Thanks Julian.

"Julian" wrote in message
...
Quick question for the electrical boffins:

AIUI mains voltage is now 230 volts -6% +10%. ie 216 to 253 -
correct or
rubbish?

My question is how is it measured? I've stuck my AVO across the
incomers to
the main fuse box, and can get the voltage down to about 216v if I
switch on
about 6.5KWs of electrical load on the property - without any
substantial
load the voltage is nearer 250V. So, under what load condition is
the
voltage measured?

Thanks Julian.



My immediate reaction to your figures is that you have a high
resistance in your feed to the property - no way should 6.5 Kw drop 34
volts or 13.6%

AWEM

"Julian" wrote in message
...
Quick question for the electrical boffins:

AIUI mains voltage is now 230 volts -6% +10%. ie 216 to 253 - correct or
rubbish?

My question is how is it measured? I've stuck my AVO across the incomers
to
the main fuse box, and can get the voltage down to about 216v if I switch
on
about 6.5KWs of electrical load on the property - without any substantial
load the voltage is nearer 250V. So, under what load condition is the
voltage measured?

Thanks Julian.


This is apalling!
34 volts drop when you are drawing 26amps. So that is about a kW going to
waste somewhere. At least if you are measuring this at the incomers, you are
not paying for this lost power directly.

It is just possible that off load you are measuring a falsely high value due
to a non sinusoidal waveform and the way an avo treats that ( peak reading,
RMS correction).
Maybe repeat the measurements with a true RMS meter to check this.

To answer your question, it does not matter too much what load the voltage
is measured because it should not vary that much.

Bob

Julian wrote:

Quick question for the electrical boffins:

AIUI mains voltage is now 230 volts -6% +10%. ie 216 to 253 - correct or
rubbish?

That is the specification. In reality much of the UK supply is still at
240V like it always was since that meets the above spec.

My question is how is it measured? I've stuck my AVO across the incomers to
the main fuse box, and can get the voltage down to about 216v if I switch on
about 6.5KWs of electrical load on the property - without any substantial
load the voltage is nearer 250V. So, under what load condition is the
voltage measured?

Are you out in the sticks with a long overhead supply?

It sounds as if your supply has a rather higher than desireable
impedance. If you have a 60A supply and are dropping 34V on a load of
only 27A that would suggest you are going to be down to 175V on full
load, which is way too low, and likely to cause problems.

I think I would be tempted to contact the supplier about that.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"John Rumm" wrote in message
...
Julian wrote:

Quick question for the electrical boffins:

AIUI mains voltage is now 230 volts -6% +10%. ie 216 to 253 - correct or
rubbish?

That is the specification. In reality much of the UK supply is still at
240V like it always was since that meets the above spec.

My question is how is it measured? I've stuck my AVO across the incomers
to the main fuse box, and can get the voltage down to about 216v if I
switch on about 6.5KWs of electrical load on the property - without any
substantial load the voltage is nearer 250V. So, under what load
condition is the voltage measured?

Are you out in the sticks with a long overhead supply?

It sounds as if your supply has a rather higher than desireable impedance.
If you have a 60A supply and are dropping 34V on a load of only 27A that
would suggest you are going to be down to 175V on full load, which is way
too low, and likely to cause problems.

I think I would be tempted to contact the supplier about that.

Thanks to all the replies. You've made me more sure now that I do have a
problem because I'm having difficulty welding with large rods, in my old
house with the same equipment it was fine.

Regarding my supply, I have a transformer up the top of a pole in my garden,
this is a small jobby and supplies my next door neighbour too, but that's
all it does. Here it is:
http://freespace.virgin.net/julian.s...ransformer.JPG The other wires are
telephone. There's a lot of very old looking wires up there, I guess some
connections may have gone high resistance?

Regarding a true RMS meter, I don't have such an animal, but I'll see if I
can borrow one. My meter is a cheap Clarke thing.

I'm going to repeat my tests, just to make sure of myself and then contact
the supplier. What is full rated load, I note that I have a 100amp supplier
fuse?

Thanks again.

Julian.

"Julian" wrote in message
...

"John Rumm" wrote in message
...
Julian wrote:

Quick question for the electrical boffins:

AIUI mains voltage is now 230 volts -6% +10%. ie 216 to 253 -
correct or
rubbish?

That is the specification. In reality much of the UK supply is
still at
240V like it always was since that meets the above spec.

My question is how is it measured? I've stuck my AVO across the
incomers
to the main fuse box, and can get the voltage down to about 216v
if I
switch on about 6.5KWs of electrical load on the property -
without any
substantial load the voltage is nearer 250V. So, under what load
condition is the voltage measured?

Are you out in the sticks with a long overhead supply?

It sounds as if your supply has a rather higher than desireable
impedance.
If you have a 60A supply and are dropping 34V on a load of only
27A that
would suggest you are going to be down to 175V on full load, which
is way
too low, and likely to cause problems.

I think I would be tempted to contact the supplier about that.

Thanks to all the replies. You've made me more sure now that I do
have a
problem because I'm having difficulty welding with large rods, in my
old
house with the same equipment it was fine.

Regarding my supply, I have a transformer up the top of a pole in my
garden,
this is a small jobby and supplies my next door neighbour too, but
that's
all it does. Here it is:
http://freespace.virgin.net/julian.s...ransformer.JPG The other
wires are
telephone. There's a lot of very old looking wires up there, I guess
some
connections may have gone high resistance?

Regarding a true RMS meter, I don't have such an animal, but I'll
see if I
can borrow one. My meter is a cheap Clarke thing.

I'm going to repeat my tests, just to make sure of myself and then
contact
the supplier. What is full rated load, I note that I have a 100amp
supplier
fuse?

Thanks again.

Julian.



100a x 230v (nominal) = 23kW

Be aware when my company fuse blew the other month, although it was in
a 100amp carrier, the fuse itself was only 60 amps. Chap from EDF was
happy to put a 100amp in having drunk his tea G Lots of big motor
with high starting current in my home workshop, as I explained to him.

AWEM

On Sun, 14 Jan 2007 14:19:48 GMT someone who may be "Julian"
wrote this:-

AIUI mains voltage is now 230 volts -6% +10%. ie 216 to 253 - correct or
rubbish?

My question is how is it measured? [snip] So, under what load condition is the
voltage measured?

A nominal supply voltage of 230V does not mean that the supply will
be at precisely 230V all the time. It means that it should be within
the specified tolerances at all times, other than when there is a
fault.

The precise voltage at your terminals at any particular time will
vary according to the load on the system (the load from you and
other customers in the area) and what the automatic voltage
regulation system is doing. It will be higher on no-load and will
reduce as load is applied, because it is (partly) a function of the
impedance of the external system. The same is true on your wiring.

Your voltage regulation doesn't sound particularly good. How many km
of 11kV route is there before it gets to the pole your photograph
shows? It is certainly worth repeating these measurements and then
having a gentle word with the technical people of your supplier,
which may take persistence on your part. It may well be that a high
resistance has developed somewhere on the external system.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

"Julian" wrote in message
...

"John Rumm" wrote in message
...
Julian wrote:

Quick question for the electrical boffins:

AIUI mains voltage is now 230 volts -6% +10%. ie 216 to 253 - correct
or
rubbish?

That is the specification. In reality much of the UK supply is still at
240V like it always was since that meets the above spec.

My question is how is it measured? I've stuck my AVO across the
incomers
to the main fuse box, and can get the voltage down to about 216v if I
switch on about 6.5KWs of electrical load on the property - without any
substantial load the voltage is nearer 250V. So, under what load
condition is the voltage measured?

Are you out in the sticks with a long overhead supply?

It sounds as if your supply has a rather higher than desireable
impedance.
If you have a 60A supply and are dropping 34V on a load of only 27A that
would suggest you are going to be down to 175V on full load, which is
way
too low, and likely to cause problems.

I think I would be tempted to contact the supplier about that.

Thanks to all the replies. You've made me more sure now that I do have a
problem because I'm having difficulty welding with large rods, in my old
house with the same equipment it was fine.

Regarding my supply, I have a transformer up the top of a pole in my
garden,
this is a small jobby and supplies my next door neighbour too, but that's
all it does. Here it is:
http://freespace.virgin.net/julian.s...ransformer.JPG The other wires
are
telephone. There's a lot of very old looking wires up there, I guess some
connections may have gone high resistance?

Regarding a true RMS meter, I don't have such an animal, but I'll see if I
can borrow one. My meter is a cheap Clarke thing.

I'm going to repeat my tests, just to make sure of myself and then contact
the supplier. What is full rated load, I note that I have a 100amp
supplier
fuse?

Thanks again.

Julian.



I doubt if the problem is cable going high resitance as the power loss would
soon escalate the problem. I suspect it is just an under rated transformer
on the end of a long line.
These sort of installations were fine in the days of light domestic loads
and with equipment (and customers) that tolerated the voltage drop every now
and then. Just not up to 21st century requirements.
You might need to lay it on a
Certainly a good plan to contact your local 'leccy board who will be
responsible for the distribution - not necessarily your electricity supplier
these days of course.
You might need to lay it on a bit thick to get them motivated.
One problem with these soggy supplies can be voltage spikes when loads are
removed which can damage things like computers, VCRs etc

Bob

Bob Minchin wrote:

You might need to lay it on a bit thick to get them motivated.
One problem with these soggy supplies can be voltage spikes when loads are
removed which can damage things like computers, VCRs etc

Persistent low voltages will also damage things like induction motors.
The fridge freezer being the most likely victim.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In message , Andrew Mawson
writes

"Julian" wrote in message
...
Quick question for the electrical boffins:

AIUI mains voltage is now 230 volts -6% +10%. ie 216 to 253 -
correct or
rubbish?

My question is how is it measured? I've stuck my AVO across the
incomers to
the main fuse box, and can get the voltage down to about 216v if I
switch on
about 6.5KWs of electrical load on the property - without any
substantial
load the voltage is nearer 250V. So, under what load condition is
the
voltage measured?

Thanks Julian.



My immediate reaction to your figures is that you have a high
resistance in your feed to the property - no way should 6.5 Kw drop 34
volts or 13.6%

Yeah -look for the molten pool of metal somewhere ...

--
geoff

"David Hansen" wrote in message
...
On Sun, 14 Jan 2007 14:19:48 GMT someone who may be "Julian"
wrote this:-

AIUI mains voltage is now 230 volts -6% +10%. ie 216 to 253 - correct or
rubbish?

My question is how is it measured? [snip] So, under what load condition is
the
voltage measured?

A nominal supply voltage of 230V does not mean that the supply will
be at precisely 230V all the time. It means that it should be within
the specified tolerances at all times, other than when there is a
fault.

The precise voltage at your terminals at any particular time will
vary according to the load on the system (the load from you and
other customers in the area) and what the automatic voltage
regulation system is doing. It will be higher on no-load and will
reduce as load is applied, because it is (partly) a function of the
impedance of the external system. The same is true on your wiring.

Your voltage regulation doesn't sound particularly good. How many km
of 11kV route is there before it gets to the pole your photograph
shows? It is certainly worth repeating these measurements and then
having a gentle word with the technical people of your supplier,
which may take persistence on your part. It may well be that a high
resistance has developed somewhere on the external system.



It may be an idea to obtain a "Loop Tester" this device can be used to
messure the effective resistance of the supply. The supply company or any
electrican will be able to do this. Also measure the voltage between N and E
when you have a high load.

In article ,
"Julian" writes:
Regarding my supply, I have a transformer up the top of a pole in my garden,
this is a small jobby and supplies my next door neighbour too, but that's
all it does. Here it is:
http://freespace.virgin.net/julian.s...ransformer.JPG The other wires are
telephone. There's a lot of very old looking wires up there, I guess some
connections may have gone high resistance?

That looks like rather a tiny transformer for two houses.
More like the sort of thing which runs the light in a phone
box out in the sticks.

--
Andrew Gabriel

In article ,
Julian wrote:

Thanks to all the replies. You've made me more sure now that I do
have a problem because I'm having difficulty welding with large
rods, in my old house with the same equipment it was fine.

Hmm... I'm glad I don't live next to anyone using
a welder in a rural area. The flickerings were a
source of constant irritation to FiL when a motor
mechanic lived next door and my pal had several
lightbulbs and his tv taken out during the dips/
/surges from his neighbour's welding. That became
the source of bitter emnity, lasting for years
and only solved when one of them died.

...... Here it is:
http://freespace.virgin.net/julian.s...ransformer.JPG

It doesn't look very large but the local electricity
Co will probably be very reluctant to spend the money
changing it. Watch out that they don't 'solve' the
low voltage problem by tapping up the transformer.

--
Tony Williams.

Andrew Gabriel wrote:

That looks like rather a tiny transformer for two houses.
More like the sort of thing which runs the light in a phone
box out in the sticks.

Yes, and old enough to date from the era when each house had one 60 W
lamp and one 5 A socket in each room, perhaps...

--
Andy

"Bob Minchin" wrote in message
...

This is apalling!
34 volts drop when you are drawing 26amps. So that is about a kW going to
waste somewhere. At least if you are measuring this at the incomers, you
are
not paying for this lost power directly.

It is just possible that off load you are measuring a falsely high value
due
to a non sinusoidal waveform and the way an avo treats that ( peak
reading,
RMS correction).
Maybe repeat the measurements with a true RMS meter to check this.

Reply to all:

OK, I borrowed my electrician friend's 'Fluke' meter and repeated the
experiment, he thinks it's true ROMS but not certain. One thing is clear, it
puts out some very different readings compared to my cheap Clarke thing -
there's a lesson there in itself!

09:00, measured at incomeres (earth and neutral seem common - there is a
word for this, but can't remember)

no appreciable load (just PC and the odd light bulb) 236volts

(all loads purely resistive)

5Kw 225v
9.5Kw 218v
12Kw 214v

Have I got a case for complaint, or should I just keep quite? I'm aware that
a new 'inverter' style high frequency welder will also solve my welding
problems, this is the main issue, dimming lights aren't something I can get
exited about. And I take the point that if the board adjust the tapings on
their transformer then I may get other problems.

Thanks Julian.

"Julian" wrote in message
...

sorry, ROMS = RMS!

James Salisbury wrote:

It may be an idea to obtain a "Loop Tester" this device can be used to
messure the effective resistance of the supply. The supply company or any
electrican will be able to do this. Also measure the voltage between N and E
when you have a high load.

There's enough data in the original article to calculate the impedance:

Voltage off-load = 250, on-load = 216, i.e. voltage drop = 34 V.

The load is stated as 6.5 kW, but that's probably a rated value at 230
or 240 V. Assuming it's 240 (most equipment in use is still rated at
240 V) the load current at 216 V will be about 24.4 A.

So the supply impedance = 34 / 24.4 = 1.4 ohm, which is awfully high.
(This figure could include some of the internal house wiring, depending
where the voltages were measured.)

If the external impedance really is that high I would worry about the
safety of the house wiring,particularly for any circuits of 30 A or
more, where the fault clearance times could be rather long and
normally-sized cables may not be adequately protected.

--
Andy

"Julian" wrote in message
...

"Bob Minchin" wrote in message
...

This is apalling!
34 volts drop when you are drawing 26amps. So that is about a kW
going to
waste somewhere. At least if you are measuring this at the
incomers, you
are
not paying for this lost power directly.

It is just possible that off load you are measuring a falsely high
value
due
to a non sinusoidal waveform and the way an avo treats that ( peak
reading,
RMS correction).
Maybe repeat the measurements with a true RMS meter to check this.

Reply to all:

OK, I borrowed my electrician friend's 'Fluke' meter and repeated
the
experiment, he thinks it's true ROMS but not certain. One thing is
clear, it
puts out some very different readings compared to my cheap Clarke
thing -
there's a lesson there in itself!

09:00, measured at incomeres (earth and neutral seem common - there
is a
word for this, but can't remember)

no appreciable load (just PC and the odd light bulb) 236volts

(all loads purely resistive)

5Kw 225v
9.5Kw 218v
12Kw 214v

Have I got a case for complaint, or should I just keep quite? I'm
aware that
a new 'inverter' style high frequency welder will also solve my
welding
problems, this is the main issue, dimming lights aren't something I
can get
exited about. And I take the point that if the board adjust the
tapings on
their transformer then I may get other problems.

Thanks Julian.




As others have said, with this sort of fault you will have excessive
light flickering, as will the other house you mention on the same
transformer. It's probably worth seeing what effect your welder has on
their lights, and maybe having a joint approach to the supplier.

AWEM

Julian wrote:

5Kw 225v
9.5Kw 218v
12Kw 214v

Have I got a case for complaint,

Where are you measuring the voltage? To avoid including voltage drop in
the house wiring you need to do it on the busbars of the consumer unit
(preferably using fused test leads), or at a point on a different final
circuit to the one you are loading.

Also take several sets of readings and average the results.

--
Andy

"Andy Wade" wrote in message
...

Where are you measuring the voltage? To avoid including voltage drop in
the house wiring you need to do it on the busbars of the consumer unit
(preferably using fused test leads), or at a point on a different final
circuit to the one you are loading.

Already stated thus:

09:00, measured at incomeres.

ie connection from meter to bus on the fuse box.

On Mon, 15 Jan 2007 08:54:40 +0000 (GMT), Tony Williams wrote:

http://freespace.virgin.net/julian.s...ransformer.JPG

It doesn't look very large but the local electricity Co will probably
be very reluctant to spend the money changing it. Watch out that they
don't 'solve' the low voltage problem by tapping up the transformer.

Well the problem is regulation not low voltage, I wouldn't expect any
competent power linesman to make that mistake. In my experience power
distribution linesmen know their stuff, you don't F about with power
distribution networks, get it wrong an there is a BIG BANG and lots of
explaining or you or a collegue are pushing up the daisies.

It does look a tad small but these trannys can deliver a surprising
amount of juice. Ours is a square boxed jobbie a bit larger than that one
but the cut out on the pole is 200A (46kW). One would assume that that
cut out is designed to go pop before the tranny catches fire...

I note that the 11kV feed is single phase, how long is this 11kV spur?
But as others have pointed out that sort of volt drop at that load
indicates 1kW or so going somewhere, a single joint dissipating that much
power wouldn't last long. Report it to the local power company, they need
to come and investigate.

--
Cheers
Dave. pam is missing e-mail

Julian wrote:
Quick question for the electrical boffins:

AIUI mains voltage is now 230 volts -6% +10%. ie 216 to 253 - correct or
rubbish?

My question is how is it measured? I've stuck my AVO across the incomers to
the main fuse box, and can get the voltage down to about 216v if I switch on
about 6.5KWs of electrical load on the property - without any substantial
load the voltage is nearer 250V. So, under what load condition is the
voltage measured?

Thanks Julian.


any load.

You are due for a replacement street/house transformer.

My old setup did this. The microwave caused every light to dim.
Transformer on a pole. Yuk.

When I finally undergrounded the supply I gort a huge steel cabinet in
the garden corner. Problems solved., I have my own 100KVA substation :-)

Contact the electricity company. They are supposed to be duty bound to
fix this for you.

Julian wrote:
"John Rumm" wrote in message
...
Julian wrote:

Quick question for the electrical boffins:

AIUI mains voltage is now 230 volts -6% +10%. ie 216 to 253 - correct or
rubbish?
That is the specification. In reality much of the UK supply is still at
240V like it always was since that meets the above spec.

My question is how is it measured? I've stuck my AVO across the incomers
to the main fuse box, and can get the voltage down to about 216v if I
switch on about 6.5KWs of electrical load on the property - without any
substantial load the voltage is nearer 250V. So, under what load
condition is the voltage measured?
Are you out in the sticks with a long overhead supply?

It sounds as if your supply has a rather higher than desireable impedance.
If you have a 60A supply and are dropping 34V on a load of only 27A that
would suggest you are going to be down to 175V on full load, which is way
too low, and likely to cause problems.

I think I would be tempted to contact the supplier about that.

Thanks to all the replies. You've made me more sure now that I do have a
problem because I'm having difficulty welding with large rods, in my old
house with the same equipment it was fine.

Regarding my supply, I have a transformer up the top of a pole in my garden,
this is a small jobby and supplies my next door neighbour too, but that's
all it does. Here it is:
http://freespace.virgin.net/julian.s...ransformer.JPG The other wires are
telephone. There's a lot of very old looking wires up there, I guess some
connections may have gone high resistance?

Regarding a true RMS meter, I don't have such an animal, but I'll see if I
can borrow one. My meter is a cheap Clarke thing.

I'm going to repeat my tests, just to make sure of myself and then contact
the supplier. What is full rated load, I note that I have a 100amp supplier
fuse?

Thanks again.

Julian.


Those transformers were out up when at most a house would draw 3KW, and
they are crap, old fashioned, use rubbish cores and you need a better one.

With luck, they may underground your supply as well, if ou suggest it to
them.

Bob Minchin wrote:
"Julian" wrote in message
...
"John Rumm" wrote in message
...
Julian wrote:

Quick question for the electrical boffins:

AIUI mains voltage is now 230 volts -6% +10%. ie 216 to 253 - correct
or
rubbish?
That is the specification. In reality much of the UK supply is still at
240V like it always was since that meets the above spec.

My question is how is it measured? I've stuck my AVO across the
incomers
to the main fuse box, and can get the voltage down to about 216v if I
switch on about 6.5KWs of electrical load on the property - without any
substantial load the voltage is nearer 250V. So, under what load
condition is the voltage measured?
Are you out in the sticks with a long overhead supply?

It sounds as if your supply has a rather higher than desireable
impedance.
If you have a 60A supply and are dropping 34V on a load of only 27A that
would suggest you are going to be down to 175V on full load, which is
way
too low, and likely to cause problems.

I think I would be tempted to contact the supplier about that.
Thanks to all the replies. You've made me more sure now that I do have a
problem because I'm having difficulty welding with large rods, in my old
house with the same equipment it was fine.

Regarding my supply, I have a transformer up the top of a pole in my
garden,
this is a small jobby and supplies my next door neighbour too, but that's
all it does. Here it is:
http://freespace.virgin.net/julian.s...ransformer.JPG The other wires
are
telephone. There's a lot of very old looking wires up there, I guess some
connections may have gone high resistance?

Regarding a true RMS meter, I don't have such an animal, but I'll see if I
can borrow one. My meter is a cheap Clarke thing.

I'm going to repeat my tests, just to make sure of myself and then contact
the supplier. What is full rated load, I note that I have a 100amp
supplier
fuse?

Thanks again.

Julian.



I doubt if the problem is cable going high resitance as the power loss would
soon escalate the problem. I suspect it is just an under rated transformer
on the end of a long line.

Just the transformner, as when mine got replaced, all problems vanished.

David Hansen wrote:

Your voltage regulation doesn't sound particularly good. How many km
of 11kV route is there before it gets to the pole your photograph
shows? It is certainly worth repeating these measurements and then
having a gentle word with the technical people of your supplier,
which may take persistence on your part. It may well be that a high
resistance has developed somewhere on the external system.


The 11KV will be OK. We are miles down one branch. Its fine. The
transformer will not be.

Dave Liquorice wrote:
On Mon, 15 Jan 2007 08:54:40 +0000 (GMT), Tony Williams wrote:

http://freespace.virgin.net/julian.s...ransformer.JPG
It doesn't look very large but the local electricity Co will probably
be very reluctant to spend the money changing it. Watch out that they
don't 'solve' the low voltage problem by tapping up the transformer.

Well the problem is regulation not low voltage, I wouldn't expect any
competent power linesman to make that mistake. In my experience power
distribution linesmen know their stuff, you don't F about with power
distribution networks, get it wrong an there is a BIG BANG and lots of
explaining or you or a collegue are pushing up the daisies.

It does look a tad small but these trannys can deliver a surprising
amount of juice. Ours is a square boxed jobbie a bit larger than that one
but the cut out on the pole is 200A (46kW). One would assume that that
cut out is designed to go pop before the tranny catches fire...


Being able to deliver the juice with little drop, and being able to
deliver it without going bang, are two different things.

You cam easily dissipate 5KW or more from a pole mounted transformer
without it going bang...


Modern ones may be better, but the one that came off my pole was circa
1948 vintage and total utter crap at anything over a few amps.

I know it wasn't the 11KV, because a new substation completely fixed it.

And an 11KV line that sags because *one* person puts a few KVA on it is
absolute balls. Its rated for ALL the people on it and maybe if they ALL
switched on their tellies you might see a sag, but not just one sodding
person.

There is only one thing that fits the bill. The transformer, or
connections to it. In short the problem is between the 11KV line and the
consumer unit.

Apart from bits of wire, there is only the pole mounted transformer,
and my experience of those is that they are useless if more than 20
years old.

In my case they were only to happy to get rid of it and have me bear
part of the cost of a bit of undergrounding I suggest the OP uses this
as a lever..to get the lot buried at little or no expense.




I note that the 11kV feed is single phase, how long is this 11kV spur?

More to the point how many other people are on it?

If more than two it ain't the problem. Otherwise half a dozen people
putting an electric fire on would dive it into the ground, at that
implied impedance.


But as others have pointed out that sort of volt drop at that load
indicates 1kW or so going somewhere, a single joint dissipating that much
power wouldn't last long. Report it to the local power company, they need
to come and investigate.

In article ,
Andrew Mawson wrote:

As others have said, with this sort of fault you will have
excessive light flickering, as will the other house you mention
on the same transformer. It's probably worth seeing what effect
your welder has on their lights, and maybe having a joint
approach to the supplier.

AFAIR, I thought that FiL made a mistake in
using the words 'motor mechanic', 'welding',
and 'flickering lights'. The electricity Co
were not interested in replacing the transformer.
I suppose an intermittant load, such as welding,
would not generate enough revenue to cover the
cost of installing an uprated transformer.

The OP does have a case here though because the
voltage is below 230 -6% with only a 12KW load.

It would be useful for him to check the voltage
when both houses are taking no load. Anywhere
near 250V would be ammunition to argue *against*
their simple getout of tapping up.

--
Tony Williams.

"The Natural Philosopher" wrote in message
...

I note that the 11kV feed is single phase, how long is this 11kV spur?

More to the point how many other people are on it?

If more than two it ain't the problem. Otherwise half a dozen people
putting an electric fire on would dive it into the ground, at that implied
impedance.

Just two of us on the 11kv line. About 500 yards up the lane there is
another group of houses and a pub, they have a transformer also. There are
three 11kv wires to that. (so that would be 3 phase) After that the three
phase 11kv wanders off across fields and I loose it from sight. Maybe Google
earth would be helpful.

Anyway, A friend of a friend once worked as an engineer for MANWEB. He's
hopefully going to chat with me tomorrow on the best tactics regarding
getting an upgrade. It does sound to me like a geriatric transformer
problem.

Thanks for the help chaps, I've got plenty of ammo now!

Julian.

Julian wrote:
"The Natural Philosopher" wrote in message
...
I note that the 11kV feed is single phase, how long is this 11kV spur?
More to the point how many other people are on it?

If more than two it ain't the problem. Otherwise half a dozen people
putting an electric fire on would dive it into the ground, at that implied
impedance.

Just two of us on the 11kv line. About 500 yards up the lane there is
another group of houses and a pub, they have a transformer also. There are
three 11kv wires to that. (so that would be 3 phase) After that the three
phase 11kv wanders off across fields and I loose it from sight. Maybe Google
earth would be helpful.

Oh so you have a two phase spur off the main 3 phase and 500 yards of
that to just the one transformer?

Hmm. Its about 30 grand a kilometer to underground..

Id say that 500 myards of spur is not goi ng to sag..lets face it its
less than an amp to give you 11KW...and to get a 20% V drop on that
would mean a 2KV drop..around 2Kohms...iI cannot see 500 yards of cable
being that high unless its about to fall apart..

Sadly I think its get the power company in, and they will just replace
the overhead transformer..


Anyway, A friend of a friend once worked as an engineer for MANWEB. He's
hopefully going to chat with me tomorrow on the best tactics regarding
getting an upgrade. It does sound to me like a geriatric transformer
problem.


99.9% certain, yes. They don;t do new overhead installations anyway,
which dates yours to probably no later than 1960 or so.


Thanks for the help chaps, I've got plenty of ammo now!


Oh, you have a cast iron case. That's probably why its sagging. These
days they use silicon iron laminations ;-) ;-)

The supply is out spec, and they HAVE to fix it.


Julian.

Tony Williams wrote:
In article ,
Andrew Mawson wrote:

As others have said, with this sort of fault you will have
excessive light flickering, as will the other house you mention
on the same transformer. It's probably worth seeing what effect
your welder has on their lights, and maybe having a joint
approach to the supplier.

AFAIR, I thought that FiL made a mistake in
using the words 'motor mechanic', 'welding',
and 'flickering lights'. The electricity Co
were not interested in replacing the transformer.
I suppose an intermittant load, such as welding,
would not generate enough revenue to cover the
cost of installing an uprated transformer.

The OP does have a case here though because the
voltage is below 230 -6% with only a 12KW load.

It would be useful for him to check the voltage
when both houses are taking no load. Anywhere
near 250V would be ammunition to argue *against*
their simple getout of tapping up.

Those pole transformers don't have taps.

I dunno if better ones are available..as I said. mostly they prefer to
underground in the case of any serious faults wherever possible.

Even 11KV overheads are not being built..too much maintenance in the gales.

In article om, Dave
Liquorice writes
On Mon, 15 Jan 2007 08:54:40 +0000 (GMT), Tony Williams wrote:

http://freespace.virgin.net/julian.s...ransformer.JPG

It doesn't look very large but the local electricity Co will probably
be very reluctant to spend the money changing it. Watch out that they
don't 'solve' the low voltage problem by tapping up the transformer.

Well the problem is regulation not low voltage, I wouldn't expect any
competent power linesman to make that mistake. In my experience power
distribution linesmen know their stuff, you don't F about with power
distribution networks, get it wrong an there is a BIG BANG and lots of
explaining or you or a collegue are pushing up the daisies.

It does look a tad small but these trannys can deliver a surprising
amount of juice. Ours is a square boxed jobbie a bit larger than that one
but the cut out on the pole is 200A (46kW). One would assume that that
cut out is designed to go pop before the tranny catches fire...

I note that the 11kV feed is single phase, how long is this 11kV spur?
But as others have pointed out that sort of volt drop at that load
indicates 1kW or so going somewhere, a single joint dissipating that much
power wouldn't last long. Report it to the local power company, they need
to come and investigate.


Seen this problem out a a number of comms sites out in the sticks.

Almost invariably an underrated transformer for today's loads. Grumble
and kick up a fuss and get the tranny uprated!...
--
Tony Sayer

Julian wrote:

OK, I borrowed my electrician friend's 'Fluke' meter and repeated the
experiment, he thinks it's true ROMS but not certain. One thing is clear, it
puts out some very different readings compared to my cheap Clarke thing -
there's a lesson there in itself!

Possibly, however you can't rely on getting the same readings each day
since it is not only your property providing the load.

The true RMS nature of the meter may have had an impact if you have a
reasonable amount of load that is not at a unity power factor.

09:00, measured at incomeres (earth and neutral seem common - there is a
word for this, but can't remember)

TN-C-S and PME usually.

no appreciable load (just PC and the odd light bulb) 236volts

(all loads purely resistive)

5Kw 225v
9.5Kw 218v
12Kw 214v

The situation was probably worse than your figures initially suggest
since I guess you were assessing the load by reading the power
consumption off the spec plate on the equipment. Since you were not
actually feeding the specified voltage, the actual power drawn by the
resistive load will have been below spec. So 214V at 11kW is probably
more likely.

If you have access to a clamp meter that you could stick round one of
the meter tails then that would give you much more accurate information
regarding the actual current load.

Have I got a case for complaint, or should I just keep quite? I'm aware that

Yes you do have a case for complaint. There is no need to mention the
welding requirement as such, but just commenting on dim lights, and
other electrical goods not functioning as they should - especially early
evening etc ought to be enough.

(A friend had a similar problem in that his garage door opener would not
work in the evening when the supply fell to 200V. Another friend
recently got compensation for a new freezer after a couple of days of
persistently low volts at his premises pushed it over the edge (although
that was down to 100V on occasion))

a new 'inverter' style high frequency welder will also solve my welding
problems, this is the main issue, dimming lights aren't something I can get
exited about. And I take the point that if the board adjust the tapings on
their transformer then I may get other problems.

You would need to point out the big swing in voltage - there is a good
chance you could be close to the upper limit with no load (including the
neighbours).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Mon, 15 Jan 2007 11:52:25 +0000, The Natural Philosopher wrote:

Id say that 500 myards of spur is not goi ng to sag..lets face it its
less than an amp to give you 11KW...and to get a 20% V drop on that
would mean a 2KV drop..around 2Kohms...iI cannot see 500 yards of cable
being that high unless its about to fall apart..

I wouldn't expect the cable to have anything like that resistance. It's a
hefty bit of copper up there. They replaced and/or upgraded the 11kV line
up the otherside of the valley that feeds the village the other year. I
was surprised at the 1/2 dia copper they where putting up...

But a few iffy connections or just one a bit high and you can loose the
regulation. The board need to come out and investigate. it could be an
underated transformer (but why has it only just come to light?) or any
number of poor joints from the CU to the 33kV substation upstream.

--
Cheers
Dave. pam is missing e-mail

"John Rumm" wrote in message
...
Julian wrote:

OK, I borrowed my electrician friend's 'Fluke' meter and repeated the
experiment, he thinks it's true ROMS but not certain. One thing is clear,
it puts out some very different readings compared to my cheap Clarke
thing - there's a lesson there in itself!

Possibly, however you can't rely on getting the same readings each day
since it is not only your property providing the load.

Yes, I understand that, but I had the two meters running together for
comparison.


The true RMS nature of the meter may have had an impact if you have a
reasonable amount of load that is not at a unity power factor.

09:00, measured at incomeres (earth and neutral seem common - there is a
word for this, but can't remember)

TN-C-S and PME usually.

no appreciable load (just PC and the odd light bulb) 236volts

(all loads purely resistive)

5Kw 225v
9.5Kw 218v
12Kw 214v

The situation was probably worse than your figures initially suggest since
I guess you were assessing the load by reading the power consumption off
the spec plate on the equipment. Since you were not actually feeding the
specified voltage, the actual power drawn by the resistive load will have
been below spec. So 214V at 11kW is probably more likely.

That's true, I never thought of that. Yes I just looked at the rating labels
(fan heaters and kettles)



If you have access to a clamp meter that you could stick round one of the
meter tails then that would give you much more accurate information
regarding the actual current load.


My mate's got one of those, I'll borrow it soonest.


Have I got a case for complaint, or should I just keep quite? I'm aware
that

Yes you do have a case for complaint. There is no need to mention the
welding requirement as such, but just commenting on dim lights, and other
electrical goods not functioning as they should - especially early evening
etc ought to be enough.

I'm on the blower to them tomorrow. I've been chatting with my neighbours,
and they have noticed dimming lights when I weld - so the problem is common
to both our installations. Next door are nice people, they're not bothered
by my welding because it is infrequent and we do favours for each other, and
they are prepared to complain too to help my case.

Julian.

"Julian" wrote in message
...

"John Rumm" wrote in message
...
Julian wrote:

OK, I borrowed my electrician friend's 'Fluke' meter and repeated
the
experiment, he thinks it's true ROMS but not certain. One thing
is clear,
it puts out some very different readings compared to my cheap
Clarke
thing - there's a lesson there in itself!

Possibly, however you can't rely on getting the same readings each
day
since it is not only your property providing the load.

Yes, I understand that, but I had the two meters running together
for
comparison.


The true RMS nature of the meter may have had an impact if you
have a
reasonable amount of load that is not at a unity power factor.

09:00, measured at incomeres (earth and neutral seem common -
there is a
word for this, but can't remember)

TN-C-S and PME usually.

no appreciable load (just PC and the odd light bulb) 236volts

(all loads purely resistive)

5Kw 225v
9.5Kw 218v
12Kw 214v

The situation was probably worse than your figures initially
suggest since
I guess you were assessing the load by reading the power
consumption off
the spec plate on the equipment. Since you were not actually
feeding the
specified voltage, the actual power drawn by the resistive load
will have
been below spec. So 214V at 11kW is probably more likely.

That's true, I never thought of that. Yes I just looked at the
rating labels
(fan heaters and kettles)



If you have access to a clamp meter that you could stick round one
of the
meter tails then that would give you much more accurate
information
regarding the actual current load.


My mate's got one of those, I'll borrow it soonest.


Have I got a case for complaint, or should I just keep quite? I'm
aware
that

Yes you do have a case for complaint. There is no need to mention
the
welding requirement as such, but just commenting on dim lights,
and other
electrical goods not functioning as they should - especially early
evening
etc ought to be enough.

I'm on the blower to them tomorrow. I've been chatting with my
neighbours,
and they have noticed dimming lights when I weld - so the problem is
common
to both our installations. Next door are nice people, they're not
bothered
by my welding because it is infrequent and we do favours for each
other, and
they are prepared to complain too to help my case.

Julian.



So you need to talk in terms of lights flickering as the 'fridge
starts up and when you put the kettle on, and going really dim with
the electric cooker, and your electronic alarm clock keeps resetting
and you're worried if perhaps there is a safety issue - and perhaps
sound a little panicky G (and should all that snow have melted SO
quickly arround their transformer last winter)

AWEM

Andrew Mawson wrote:

and you're worried if perhaps there is a safety issue - and perhaps
sound a little panicky G (and should all that snow have melted SO
quickly arround their transformer last winter)

As Andy mentioned in another post, there is a potentially serious safety
issue here.

All the circuits in your house will be protected by overcurrent devices
which you expect to open fast enough to clear a fault should one occur,
and without the wiring in the house suffering damage as a result. With a
much lower than expected voltage, you can no longer rely on this being
the case since you are outside the design parameters of the circuit and
cable, and it will take longer than expected to open the protective device.

The problem is compounded if you have a supply with Neutral and Earth
combined at the origin of the installation. Your high supply impedance
will also translate into a high earth fault loop impedance. Which in
turn could leave metal work rendered live due to a fault, in that state
for much longer than expected (assuming the circuit is no RCD protected).

If you refer to appendix 2 of the on site guide, this lists the maximum
allowable impedances for different protective devices. Note that this is
the impedance measured at the far extent of the circuit in the property,
not at the CU, and hence includes the loop impedance of the house wiring
as well as that of the supply.

For example a 30A rewireable fuse is only safe with impedances up to
0.91 ohms. A type B 32A MCB 1.2 ohms


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
The Natural Philosopher writes:

Oh so you have a two phase spur off the main 3 phase and 500 yards of
that to just the one transformer?

Hmm. Its about 30 grand a kilometer to underground..

Id say that 500 myards of spur is not goi ng to sag..lets face it its
less than an amp to give you 11KW...and to get a 20% V drop on that
would mean a 2KV drop..around 2Kohms...iI cannot see 500 yards of cable
being that high unless its about to fall apart..

A very rough rule of thumb is that a HV feed is good for
1 mile per kV, i.e. 11 miles for 11kV feed. Of course,
there are many other influencing parameters too.

--
Andrew Gabriel

Dave Liquorice wrote:
On Mon, 15 Jan 2007 11:52:25 +0000, The Natural Philosopher wrote:

Id say that 500 myards of spur is not goi ng to sag..lets face it its
less than an amp to give you 11KW...and to get a 20% V drop on that
would mean a 2KV drop..around 2Kohms...iI cannot see 500 yards of cable
being that high unless its about to fall apart..

I wouldn't expect the cable to have anything like that resistance. It's a
hefty bit of copper up there. They replaced and/or upgraded the 11kV line
up the otherside of the valley that feeds the village the other year. I
was surprised at the 1/2 dia copper they where putting up...

its not all copper..its wound round a steel core for strength..there is
a relationship between span and how fat a cable has to be to not sag and
touch the ground..or an adjacent conductor..they pick that size of steel
and wind what copper they need over the top.


But a few iffy connections or just one a bit high and you can loose the
regulation. The board need to come out and investigate. it could be an
underated transformer (but why has it only just come to light?) or any
number of poor joints from the CU to the 33kV substation upstream.

No, it can't be. It can only be in the section that is private to you,
or your load would not be able to have the impact it has without the
whole local area going down in darkness every time people switched on
'big brother'

Its a bad connection to YOUR transformer, YOUR spur or a bad transformer.

John Rumm wrote:
Andrew Mawson wrote:

and you're worried if perhaps there is a safety issue - and perhaps
sound a little panicky G (and should all that snow have melted SO
quickly arround their transformer last winter)

As Andy mentioned in another post, there is a potentially serious safety
issue here.

All the circuits in your house will be protected by overcurrent devices
which you expect to open fast enough to clear a fault should one occur,
and without the wiring in the house suffering damage as a result. With a
much lower than expected voltage, you can no longer rely on this being
the case since you are outside the design parameters of the circuit and
cable, and it will take longer than expected to open the protective device.

The problem is compounded if you have a supply with Neutral and Earth
combined at the origin of the installation. Your high supply impedance
will also translate into a high earth fault loop impedance. Which in
turn could leave metal work rendered live due to a fault, in that state
for much longer than expected (assuming the circuit is no RCD protected).

If you refer to appendix 2 of the on site guide, this lists the maximum
allowable impedances for different protective devices. Note that this is
the impedance measured at the far extent of the circuit in the property,
not at the CU, and hence includes the loop impedance of the house wiring
as well as that of the supply.

For example a 30A rewireable fuse is only safe with impedances up to
0.91 ohms. A type B 32A MCB 1.2 ohms


I think most pole mounted transformers simply have an earth strap
running down the pole..connected to neutral ..and a local earth spike.

On Mon, 15 Jan 2007 11:54:49 +0000, The Natural Philosopher wrote:

Tony Williams wrote:
In article ,
Andrew Mawson wrote:

As others have said, with this sort of fault you will have
excessive light flickering, as will the other house you mention
on the same transformer. It's probably worth seeing what effect
your welder has on their lights, and maybe having a joint
approach to the supplier.

AFAIR, I thought that FiL made a mistake in
using the words 'motor mechanic', 'welding',
and 'flickering lights'. The electricity Co
were not interested in replacing the transformer.
I suppose an intermittant load, such as welding,
would not generate enough revenue to cover the
cost of installing an uprated transformer.

The OP does have a case here though because the
voltage is below 230 -6% with only a 12KW load.

It would be useful for him to check the voltage
when both houses are taking no load. Anywhere
near 250V would be ammunition to argue *against*
their simple getout of tapping up.

Those pole transformers don't have taps.

Oh yes they do.

--
the dot wanderer at tesco dot net