Today I recieved my British Gas electricity monitor and I have noticed that
when I turn on the kitchen lights that are two 58 watt T8 tubes running on
two conventional ballast gear trays the wattage on the monitor shows a draw
of 160 watts which means that if the tube draws 58w then the ballast is
drawing 22watts, would this be correct?.

Trevor Smith

Trevor Smith wrote:
Today I recieved my British Gas electricity monitor and I have noticed
that when I turn on the kitchen lights that are two 58 watt T8 tubes
running on two conventional ballast gear trays the wattage on the
monitor shows a draw of 160 watts which means that if the tube draws 58w
then the ballast is drawing 22watts, would this be correct?.

Trevor Smith
Just be aware that any device that only measures current cannot be an
accurate watt-meter.

A

In article ,
Andy Dee writes:
Trevor Smith wrote:
Today I recieved my British Gas electricity monitor and I have noticed
that when I turn on the kitchen lights that are two 58 watt T8 tubes
running on two conventional ballast gear trays the wattage on the
monitor shows a draw of 160 watts which means that if the tube draws 58w
then the ballast is drawing 22watts, would this be correct?.

Trevor Smith
Just be aware that any device that only measures current cannot be an
accurate watt-meter.

Yes, it can't take the power factor into account.
Your fitting must have a power factor correction capacitor, or for a
a 58W tube, it would register about 2.2 times the actual power used.
A capacitor can't fully compensate though, because part of the low
power factor is not simply due to phase shift, and the capacitor can
only compensate for the phase shift component.

Ballast efficiency is marked with an EEI (Energy Efficiency Index)
rating on the ballast.

With the information you've given, I can't tell how much of the 22W
is a misreading due to power factor, and how much is ballast losses.
It can't possibly all be ballast losses, because the ballast would
overheat. For a 58W tube and ballast, max ballast losses a
EEI=D 12W
EEI=C 12W
EEI=B2 9W
EEI=B1 6W

If you are interested, you could pop the cover off, and read what
the ballast EEI rating is. It's no longer legal to sell EEI=C or D
ballasts in the EU.

If you want a more efficient light, rewire the luminaire with an
electronic ballast. You can get one which will do twin tubes
(although both will go out when one dies), or separate ballasts
for each tube. Electronic ballasts are required to be more efficient
than even the EEI=B1 rating.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel wrote:


Yes, it can't take the power factor into account.
Nor the supply voltage.
A

On Fri, 11 Dec 2009 17:25:54 -0000, Trevor Smith wrote:

Today I recieved my British Gas electricity monitor and I have noticed that
when I turn on the kitchen lights that are two 58 watt T8 tubes running on
two conventional ballast gear trays the wattage on the monitor shows a draw
of 160 watts which means that if the tube draws 58w then the ballast is
drawing 22watts, would this be correct?.

Trevor Smith

Had one of those and gave it away! Damned thing was telling me that a 15W
CFL was 30W; also that my PC was about 100W - it'd catch fire! The CFL was
near enough PF, but the PC has ~99% PF...

I just wanted to know what's watt.
--
Peter.
The head of a pin will hold more angels if
it's been flattened with an angel-grinder.

On Dec 11, 6:12*pm, (Andrew Gabriel)
wrote:

Ballast efficiency is marked with an EEI (Energy Efficiency Index)
rating on the ballast.

With the information you've given, I can't tell how much of the 22W
is a misreading due to power factor, and how much is ballast losses.
It can't possibly all be ballast losses, because the ballast would
overheat. For a 58W tube and ballast, max ballast losses a
EEI=D 12W
EEI=C 12W
EEI=B2 9W
EEI=B1 6W

If you are interested, you could pop the cover off, and read what
the ballast EEI rating is. It's no longer legal to sell EEI=C or D
ballasts in the EU.

If you want a more efficient light, rewire the luminaire with an
electronic ballast. You can get one which will do twin tubes
(although both will go out when one dies), or separate ballasts
for each tube. Electronic ballasts are required to be more efficient
than even the EEI=B1 rating.

mind if that's pasted into the wiki?
http://wiki.diyfaq.org.uk/index.php?title=Fluorescent


NT

"Andrew Gabriel" wrote in message
...
In article ,
Andy Dee writes:
Trevor Smith wrote:
Today I recieved my British Gas electricity monitor and I have noticed
that when I turn on the kitchen lights that are two 58 watt T8 tubes
running on two conventional ballast gear trays the wattage on the
monitor shows a draw of 160 watts which means that if the tube draws 58w
then the ballast is drawing 22watts, would this be correct?.

Trevor Smith
Just be aware that any device that only measures current cannot be an
accurate watt-meter.

Yes, it can't take the power factor into account.
Your fitting must have a power factor correction capacitor, or for a
a 58W tube, it would register about 2.2 times the actual power used.
A capacitor can't fully compensate though, because part of the low
power factor is not simply due to phase shift, and the capacitor can
only compensate for the phase shift component.

Ballast efficiency is marked with an EEI (Energy Efficiency Index)
rating on the ballast.

With the information you've given, I can't tell how much of the 22W
is a misreading due to power factor, and how much is ballast losses.
It can't possibly all be ballast losses, because the ballast would
overheat. For a 58W tube and ballast, max ballast losses a
EEI=D 12W
EEI=C 12W
EEI=B2 9W
EEI=B1 6W

If you are interested, you could pop the cover off, and read what
the ballast EEI rating is. It's no longer legal to sell EEI=C or D
ballasts in the EU.

If you want a more efficient light, rewire the luminaire with an
electronic ballast. You can get one which will do twin tubes
(although both will go out when one dies), or separate ballasts
for each tube. Electronic ballasts are required to be more efficient
than even the EEI=B1 rating.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Just had a look and the ballasts are EEI=B2 and whilst I was doing that I
check again the load on the monitor and it now shows that the two lights are
drawing 120 watts which means with the EEI=B2 ballast losses taken into
account they are more efficient than they should be.
Conclusion, these monitors are a very rough guide and I will properly do
what PeterC did and give it away.

Trevor Smith

In article ,
NT writes:
On Dec 11, 6:12*pm, (Andrew Gabriel)
wrote:
Ballast efficiency is marked with an EEI (Energy Efficiency Index)
rating on the ballast.

With the information you've given, I can't tell how much of the 22W
is a misreading due to power factor, and how much is ballast losses.
It can't possibly all be ballast losses, because the ballast would
overheat. For a 58W tube and ballast, max ballast losses a
EEI=D 12W
EEI=C 12W
EEI=B2 9W
EEI=B1 6W

If you are interested, you could pop the cover off, and read what
the ballast EEI rating is. It's no longer legal to sell EEI=C or D
ballasts in the EU.

If you want a more efficient light, rewire the luminaire with an
electronic ballast. You can get one which will do twin tubes
(although both will go out when one dies), or separate ballasts
for each tube. Electronic ballasts are required to be more efficient
than even the EEI=B1 rating.
mind if that's pasted into the wiki?
http://wiki.diyfaq.org.uk/index.php?title=Fluorescent

Yes sure. This is all for magnetic ballasts.

For electronic ballasts, there's A3, A2, and A1, but it's more
complicated how they're used, and I haven't looked up the precise
details. I think A3 only allows a total of about 1W more than the
tube power rating, and A2 and A1 have total power consumptions
less than the tube rating. This works by underruning the tubes,
and relying on the HF operation being more efficient to get the
same light output as at 50Hz operation. Would need to look into
that some more before it's accurate enough for the wiki though.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Dec 11, 11:15*pm, (Andrew Gabriel)
wrote:
In article ,
* * * * NT writes:



On Dec 11, 6:12*pm, (Andrew Gabriel)
wrote:
Ballast efficiency is marked with an EEI (Energy Efficiency Index)
rating on the ballast.

With the information you've given, I can't tell how much of the 22W
is a misreading due to power factor, and how much is ballast losses.
It can't possibly all be ballast losses, because the ballast would
overheat. For a 58W tube and ballast, max ballast losses a
EEI=D 12W
EEI=C 12W
EEI=B2 9W
EEI=B1 6W

If you are interested, you could pop the cover off, and read what
the ballast EEI rating is. It's no longer legal to sell EEI=C or D
ballasts in the EU.

If you want a more efficient light, rewire the luminaire with an
electronic ballast. You can get one which will do twin tubes
(although both will go out when one dies), or separate ballasts
for each tube. Electronic ballasts are required to be more efficient
than even the EEI=B1 rating.
mind if that's pasted into the wiki?
http://wiki.diyfaq.org.uk/index.php?title=Fluorescent

Yes sure. This is all for magnetic ballasts.

For electronic ballasts, there's A3, A2, and A1, but it's more
complicated how they're used, and I haven't looked up the precise
details. I think A3 only allows a total of about 1W more than the
tube power rating, and A2 and A1 have total power consumptions
less than the tube rating. This works by underruning the tubes,
and relying on the HF operation being more efficient to get the
same light output as at 50Hz operation. Would need to look into
that some more before it's accurate enough for the wiki though.

cheers. If you do get that extra data I'll put it in.


NT

On Fri, 11 Dec 2009 23:37:41 GMT, wrote:

On 11 Dec,
"Trevor Smith" wrote:

Today I recieved my British Gas electricity monitor and I have noticed that
when I turn on the kitchen lights that are two 58 watt T8 tubes running on
two conventional ballast gear trays the wattage on the monitor shows a draw
of 160 watts which means that if the tube draws 58w then the ballast is
drawing 22watts, would this be correct?.

It won't account for power factor, so the difference will be reactive "power"
which is sucked from the mains then returned.

I've just been checking various appliances on my plug in power meter. I've
been assuming the figures in the handbook of my 2 year old Philips TV are
correct. It claims less than 1W on standby so I've been leaving it on
standby.

I now find it's taking nearer 25W and about 4W when switched off. Trading
standards?? And do I demand a refund?

Interesting - I've a 3yo Philips TV that shows 0.9 - 1W on the plug-in
meter and I used to leave that on standby sometimes; now do so only for 30
min. gaps or less.
I never checked it with BG's thing - wish had. But which is correct?
--
Peter.
The head of a pin will hold more angels if
it's been flattened with an angel-grinder.

On 11 Dec, 23:37, wrote:
I now find it's taking nearer 25W and about 4W when switched off. Trading
standards?? And do I demand a refund?

How long did you wait after switching it into standby? Our Panasonic
TVs only enter their very low power standby mode after a few minutes,
when there is an audible click from (presumably) a relay in the set.
Until then the power consumption is much higher.

I suggest you repeat your measurement after the TV has been in standby
for, say, at least ten minutes.

Richard.
http://www.rtrussell.co.uk/