Over the last week or so we've had 3 lamps literally explode into fragments.
Not just go, explode & shower glass everywhere.

One was a 60w incandescent, one a GU10 and the other a cooker hood lamp.
The first exploded when switched on, the others just exploded whilst on.
Not all at the same time mind.

Our power is regularly 250v, can't check right now, left my DMM on a job.
We have a substation at the end of the cul-delsac about 12 houses away.

Any ideas? Some kind of voltage spike?




--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

On Mon, 12 Apr 2010 21:05:34 +0100, The Medway Handyman wrote:

Our power is regularly 250v, can't check right now, left my DMM on a
job.

250 is getting close to the upper limit of 253v. I'd monitor it for a
while (a decent UPS with voltage measuring capability connected to a
PC is handy to log this sort of stuff) and make a complaint.

Any ideas? Some kind of voltage spike?

Could be, do you get visible changes in output from incandescent
lamps?

Your post made me look at the voltage plot here and I find that just
before 2230 last night the volts dropped from about 243 to 228 and
stayed there until 0630 when they recovered back to 240. There where
a couple of other minor drops just after 0700 and nearly 0830 down to
a tad above 230. The overnight drop and the suddenness of it coming
and going is most unusual, did the grid have a whoopsie or was it
something local?

--
Cheers
Dave.

The Medway Handyman submitted this idea :
Our power is regularly 250v, can't check right now, left my DMM on a job. We
have a substation at the end of the cul-delsac about 12 houses away.

There seem to be quite a few 230v lamps getting into the country and
they would be well over run at 250v. If you are regularly seeing 250v
then I bet your lamps do not last long anyway, even if 240v and despite
250 being within spec., it might be worth your talking with your
supplier.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

"The Medway Handyman" wrote in message
...
Over the last week or so we've had 3 lamps literally explode into
fragments. Not just go, explode & shower glass everywhere.

One was a 60w incandescent, one a GU10 and the other a cooker hood lamp.
The first exploded when switched on, the others just exploded whilst on.
Not all at the same time mind.

Our power is regularly 250v, can't check right now, left my DMM on a job.
We have a substation at the end of the cul-delsac about 12 houses away.

Any ideas? Some kind of voltage spike?




--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

Any neighbours reported anything similar?

The only exploding lamps I have ever seen have been in very cold and wet
conditions apart from one cfl which just exploded at switch on.

Adam

Dave Liquorice wrote:
On Mon, 12 Apr 2010 21:05:34 +0100, The Medway Handyman wrote:

Our power is regularly 250v, can't check right now, left my DMM on a
job.

250 is getting close to the upper limit of 253v. I'd monitor it for a
while (a decent UPS with voltage measuring capability connected to a
PC is handy to log this sort of stuff) and make a complaint.

Any ideas? Some kind of voltage spike?

Could be, do you get visible changes in output from incandescent
lamps?

Your post made me look at the voltage plot here and I find that just
before 2230 last night the volts dropped from about 243 to 228 and
stayed there until 0630 when they recovered back to 240. There where
a couple of other minor drops just after 0700 and nearly 0830 down to
a tad above 230. The overnight drop and the suddenness of it coming
and going is most unusual, did the grid have a whoopsie or was it
something local?

Voltage disturbances will almost certainly be local ( below 33Kv) there
are tap changers at 33Kv and higher. You will see grid problems in terms
of frequency long before there will be voltage drops..

James Salisbury laid this down on his screen :
Dave Liquorice wrote:
On Mon, 12 Apr 2010 21:05:34 +0100, The Medway Handyman wrote:

Our power is regularly 250v, can't check right now, left my DMM on a job.

250 is getting close to the upper limit of 253v. I'd monitor it for a
while (a decent UPS with voltage measuring capability connected to a
PC is handy to log this sort of stuff) and make a complaint.

Any ideas? Some kind of voltage spike?

Could be, do you get visible changes in output from incandescent
lamps?

Your post made me look at the voltage plot here and I find that just
before 2230 last night the volts dropped from about 243 to 228 and
stayed there until 0630 when they recovered back to 240. There where
a couple of other minor drops just after 0700 and nearly 0830 down to
a tad above 230. The overnight drop and the suddenness of it coming
and going is most unusual, did the grid have a whoopsie or was it
something local?

Voltage disturbances will almost certainly be local ( below 33Kv) there are
tap changers at 33Kv and higher. You will see grid problems in terms of
frequency long before there will be voltage drops..

...and somewhere on the web is a live mains frequency display.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

"Harry Bloomfield" wrote in message . uk...
James Salisbury laid this down on his screen :
Dave Liquorice wrote:
On Mon, 12 Apr 2010 21:05:34 +0100, The Medway Handyman wrote:

Our power is regularly 250v, can't check right now, left my DMM on a job.

250 is getting close to the upper limit of 253v. I'd monitor it for a
while (a decent UPS with voltage measuring capability connected to a
PC is handy to log this sort of stuff) and make a complaint.

Any ideas? Some kind of voltage spike?

Could be, do you get visible changes in output from incandescent
lamps? Your post made me look at the voltage plot here and I find that just
before 2230 last night the volts dropped from about 243 to 228 and
stayed there until 0630 when they recovered back to 240. There where
a couple of other minor drops just after 0700 and nearly 0830 down to
a tad above 230. The overnight drop and the suddenness of it coming
and going is most unusual, did the grid have a whoopsie or was it
something local?

Voltage disturbances will almost certainly be local ( below 33Kv) there are tap changers at 33Kv and higher. You will see grid
problems in terms of frequency long before there will be voltage drops..

..and somewhere on the web is a live mains frequency display.

That and a lot more here
www.bmreports.com (It dosn't seem to like Google Chrome BTW)

--
Graham.

%Profound_observation%

ARWadsworth wrote:
"The Medway Handyman" wrote in
message ...
Over the last week or so we've had 3 lamps literally explode into
fragments. Not just go, explode & shower glass everywhere.

One was a 60w incandescent, one a GU10 and the other a cooker hood
lamp. The first exploded when switched on, the others just exploded
whilst on. Not all at the same time mind.

Our power is regularly 250v, can't check right now, left my DMM on a
job. We have a substation at the end of the cul-delsac about 12
houses away. Any ideas? Some kind of voltage spike?




--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

Any neighbours reported anything similar?

I'll have to ask.

The only exploding lamps I have ever seen have been in very cold and
wet conditions apart from one cfl which just exploded at switch on.

Far from it here.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

Harry Bloomfield wrote:
The Medway Handyman submitted this idea :
Our power is regularly 250v, can't check right now, left my DMM on a
job. We have a substation at the end of the cul-delsac about 12
houses away.

There seem to be quite a few 230v lamps getting into the country and
they would be well over run at 250v. If you are regularly seeing 250v
then I bet your lamps do not last long anyway, even if 240v and
despite 250 being within spec., it might be worth your talking with
your supplier.

Good point. I had a spate of measuring a while ago & it was frequently
250/252v.

I'll have to start a daily log.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

On Apr 12, 9:05*pm, "The Medway Handyman" davidl...@no-spam-
blueyonder.co.uk wrote:
Over the last week or so we've had 3 lamps literally explode into fragments.
Not just go, explode & shower glass everywhere.

One was a 60w incandescent, one a GU10 and the other a cooker hood lamp.
The first exploded when switched on, the others just exploded whilst on.
Not all at the same time mind.

Our power is regularly 250v, can't check right now, left my DMM on a job.
We have a substation at the end of the cul-delsac about 12 houses away.

Any ideas? *Some kind of voltage spike?


Small overvoltages dont cause explosions, they cause reduced filament
life. Arcover as the filament breaks can cause explosion. Are they on
fuses or mcbs?


NT

The Medway Handyman wrote:
Over the last week or so we've had 3 lamps literally explode into fragments.
Not just go, explode & shower glass everywhere.

One was a 60w incandescent, one a GU10 and the other a cooker hood lamp.
The first exploded when switched on, the others just exploded whilst on.
Not all at the same time mind.

Our power is regularly 250v, can't check right now, left my DMM on a job.
We have a substation at the end of the cul-delsac about 12 houses away.

Any ideas? Some kind of voltage spike?

A clear case of demonic possession. Have you noticed your wife's head rotating
at all?

..and somewhere on the web is a live mains frequency display.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk



Here is one: http://www.dynamicdemand.co.uk/grid.htm

NT wrote:
On Apr 12, 9:05 pm, "The Medway Handyman" davidl...@no-spam-
blueyonder.co.uk wrote:
Over the last week or so we've had 3 lamps literally explode into
fragments. Not just go, explode & shower glass everywhere.

One was a 60w incandescent, one a GU10 and the other a cooker hood
lamp. The first exploded when switched on, the others just exploded
whilst on. Not all at the same time mind.

Our power is regularly 250v, can't check right now, left my DMM on a
job. We have a substation at the end of the cul-delsac about 12
houses away.

Any ideas? Some kind of voltage spike?


Small overvoltages dont cause explosions, they cause reduced filament
life. Arcover as the filament breaks can cause explosion. Are they on
fuses or mcbs?

Fuses


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

Gib Bogle wrote:
The Medway Handyman wrote:
Over the last week or so we've had 3 lamps literally explode into
fragments. Not just go, explode & shower glass everywhere.

One was a 60w incandescent, one a GU10 and the other a cooker hood
lamp. The first exploded when switched on, the others just exploded
whilst on. Not all at the same time mind.

Our power is regularly 250v, can't check right now, left my DMM on a
job. We have a substation at the end of the cul-delsac about 12
houses away. Any ideas? Some kind of voltage spike?

A clear case of demonic possession. Have you noticed your wife's
head rotating at all?

Only after a few cans of special brew.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

Vortex5 presented the following explanation :

..and somewhere on the web is a live mains frequency display.

-- Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk



Here is one: http://www.dynamicdemand.co.uk/grid.htm

That's the one, thanks.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On Apr 13, 5:39*pm, "The Medway Handyman" davidl...@no-spam-
blueyonder.co.uk wrote:
NT wrote:
On Apr 12, 9:05 pm, "The Medway Handyman" davidl...@no-spam-
blueyonder.co.uk wrote:
Over the last week or so we've had 3 lamps literally explode into
fragments. Not just go, explode & shower glass everywhere.

One was a 60w incandescent, one a GU10 and the other a cooker hood
lamp. The first exploded when switched on, the others just exploded
whilst on. Not all at the same time mind.

Our power is regularly 250v, can't check right now, left my DMM on a
job. We have a substation at the end of the cul-delsac about 12
houses away.

Any ideas? Some kind of voltage spike?

Small overvoltages dont cause explosions, they cause reduced filament
life. Arcover as the filament breaks can cause explosion. Are they on
fuses or mcbs?

Fuses


Ah, going to MCBs would mean much quicker blows, fair chance it'd
prevent it happening. Might also be worth checking you've got the
right fuse wire in, not 10A or 15A. And maybe that, as I've seen
before, you don't have more than one fuse parallelled.


NT

Vortex5 wrote:


..and somewhere on the web is a live mains frequency display.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk



Here is one: http://www.dynamicdemand.co.uk/grid.htm

That frequency in some way represents the frequency of "generators all over the
country". I wonder how much it actually varies throughout the country. I know
they are all locked to the same frequency, but I doubt that the synching is perfect.

On Wed, 14 Apr 2010 12:13:09 +1200, Gib Bogle
wibbled:

Vortex5 wrote:


..and somewhere on the web is a live mains frequency display.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk



Here is one: http://www.dynamicdemand.co.uk/grid.htm

That frequency in some way represents the frequency of "generators all
over the country". I wonder how much it actually varies throughout the
country. I know they are all locked to the same frequency, but I doubt
that the synching is perfect.

On *average* it is perfect - think what would happen if one end of the
country became 180 degrees out of phase with the other which would
eventually happen if there was a sustained difference in frequency. There
are phase variations over the grid though.

What does happen though, is due to very long transmission lines, there
can occur oscillations in the phase difference, most pronounced between
southern England and Scotland, but there is no net difference in the
average cycle counts.

The danger with that is if the oscillations become pronounced it can lead
to high currents in the transmission lines with the risks of trips
opening.

Not sure what National Grid do now, but back when the main control room
was in London. there was a device nicknamed "the Scottish
Wobblemeter" (really) that indicated the phase difference between the two
ends of the grid. If that started oscillating, corrective measures may be
needed urgently.



--
Tim Watts

Managers, politicians and environmentalists: Nature's carbon buffer.

On Wed, 14 Apr 2010 06:24:07 +0000, Tim Watts wibbled:

On Wed, 14 Apr 2010 12:13:09 +1200, Gib Bogle
wibbled:

Vortex5 wrote:


..and somewhere on the web is a live mains frequency display.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk



Here is one: http://www.dynamicdemand.co.uk/grid.htm

That frequency in some way represents the frequency of "generators all
over the country". I wonder how much it actually varies throughout the
country. I know they are all locked to the same frequency, but I doubt
that the synching is perfect.

On *average* it is perfect - think what would happen if one end of the
country became 180 degrees out of phase with the other which would
eventually happen if there was a sustained difference in frequency.
There are phase variations over the grid though.

What does happen though, is due to very long transmission lines, there
can occur oscillations in the phase difference, most pronounced between
southern England and Scotland, but there is no net difference in the
average cycle counts.

The danger with that is if the oscillations become pronounced it can
lead to high currents in the transmission lines with the risks of trips
opening.

Not sure what National Grid do now, but back when the main control room
was in London. there was a device nicknamed "the Scottish Wobblemeter"
(really) that indicated the phase difference between the two ends of the
grid. If that started oscillating, corrective measures may be needed
urgently.

BTW - this is why the Interconnectors to France and Ireland are DC - the
impossibility of phase locking to another sizeable system with a weedly
link.



--
Tim Watts

Managers, politicians and environmentalists: Nature's carbon buffer.

Tim Watts wrote:

On *average* it is perfect - think what would happen if one end of the
country became 180 degrees out of phase with the other which would
eventually happen if there was a sustained difference in frequency. There
are phase variations over the grid though.

What does happen though, is due to very long transmission lines, there
can occur oscillations in the phase difference, most pronounced between
southern England and Scotland, but there is no net difference in the
average cycle counts.

The danger with that is if the oscillations become pronounced it can lead
to high currents in the transmission lines with the risks of trips
opening.

Not sure what National Grid do now, but back when the main control room
was in London. there was a device nicknamed "the Scottish
Wobblemeter" (really) that indicated the phase difference between the two
ends of the grid. If that started oscillating, corrective measures may be
needed urgently.

It boggles the mind.

wrote:
On 14 Apr,
Gib Bogle wrote:

That frequency in some way represents the frequency of "generators all over
the country". I wonder how much it actually varies throughout the
country. I know they are all locked to the same frequency, but I doubt
that the synching is perfect.

They are all connected together so are either synced, or there is a big bang!

There may be some phase shift around the country, but they are all locked to
the same frequency, unless there is some break in the national grid.

Larger systems can become unstable when operated as a single grid,
continental Europe (and probably the US) is too large and is not a single
locked grid.

Actually most of Europe is one grid http://www.entsoe.eu/index.php?id=10

James Salisbury wrote:
wrote:
On 14 Apr, Gib Bogle wrote:

That frequency in some way represents the frequency of "generators
all over
the country". I wonder how much it actually varies throughout the
country. I know they are all locked to the same frequency, but I doubt
that the synching is perfect.

They are all connected together so are either synced, or there is a
big bang!

There may be some phase shift around the country, but they are all
locked to
the same frequency, unless there is some break in the national grid.

Larger systems can become unstable when operated as a single grid,
continental Europe (and probably the US) is too large and is not a single
locked grid.
Actually most of Europe is one grid http://www.entsoe.eu/index.php?id=10

er actually its five..

and 'one grid' is misleading.

You cant actually have a large area GRID, you can have a large area
interconnected and broadly synchronous zone though.

What is not permissible is a 'ring' as the propagation delays from one
part to another would result in large circulating currents wasting power.

The Natural Philosopher wrote:
James Salisbury wrote:
wrote:
On 14 Apr, Gib Bogle wrote:

That frequency in some way represents the frequency of "generators
all over
the country". I wonder how much it actually varies throughout the
country. I know they are all locked to the same frequency, but I
doubt
that the synching is perfect.

They are all connected together so are either synced, or there is a
big bang!

There may be some phase shift around the country, but they are all
locked to
the same frequency, unless there is some break in the national grid.

Larger systems can become unstable when operated as a single grid,
continental Europe (and probably the US) is too large and is not a
single
locked grid.
Actually most of Europe is one grid http://www.entsoe.eu/index.php?id=10

er actually its five..

and 'one grid' is misleading.

You cant actually have a large area GRID, you can have a large area
interconnected and broadly synchronous zone though.

What is not permissible is a 'ring' as the propagation delays from one
part to another would result in large circulating currents wasting power.
I would say that;

Austria, Belgium, Bosnia-Herzegovina, Bulgaria, Czech Republic, Croatia,
Denmark (West), France, FYROM, Germany, Greece, Hungary, Italy,
Luxemburg, Montenegro, Nederland, Poland, Portugal, Romania, Serbia,
Slovakia, Slovenia, Spain and Switzerland

Could be seen as _most_ of Europe....