Why are my halogen downlighters cheaper on than off????

[dnoble]

My wife set up a British Gas monitor thingy to sit next to the one from our new solar panel which shows how much is being generated. I've noticed when I switch on 9 downlighters in the kitchen the power consumption drops by about 120w and jumps back up when they go off! I've checked this lots of times and am sure it's not a coincidence. Also I dont think it can be reading "back to front" (if that's possible) as it jumps up normally if I switch on the kettle etc.
I've noticed the halogen bulbs dont last long (replaced at least twice a year) Could there be some weird thing wrongwith the transformer accounting for this apparent anomaly?
Thanks in advance for any thoughts.
Dan

[clivejo]

I think your British Gas monitor is one of those ones that strap on the cable and measure the electromagnetic field.  Unfortunately, these are not accurate and can give misleading reading when powering different types of loads (resistive, inductive etc) as they have differing Power factors.  I have a wheel type meter and one of these wireless monitors and they are always out of sync.  The manual of the wireless monitor does give a warning that it should only be use as a monitor and NOT a meter!

Its probably the transformers used in your halogen lights causing the misreading of the actual power being used, and its definitely NOT cheaper to have lights on than off!

[Billy]

Don't know about that but they don't last long.  I replaced nearly all my halogens with leds and have reaped the benefits.

billy
 

what you don''t use you don't have to generate!

[dnoble]

I take your point, Clive, but wouldn't that relate more to accuracy? This seems to be defying the laws of physics!

[clivejo]

Its not defying physics, its the way the device measures and approximates consumption.  All very interesting stuff - for more information http://en.wikipedia.org/wiki/Power_factor

[HalcyonRichard]

Hi,
    You mention it's next to the generation meter. Are you measuring generation or consumption ? And how is your system wired and monitored - one explaination is that your lights are taken from your "generated power" before the meter. And that the ring main could be wired after the meter(s).

P.S.  I have 9 halogens and have had to replace 1 in five years. This I think is due to them being on dimmers so usually not run at 100% most of the time. Also the dimmer will provide a soft start so less stress on power up - when they usually blow.

Regards Richard

[ecogeorge]

I've noticed when I switch on 9 downlighters

You've got 9 HALOGEN downlighters   
Thats 315w at 35 w each or 450w at 50w each -have you not got any heating in the house or is a competition to get the highest electricity bill ?
Get some high power leds in there quick man , while we've still got a planet to save.
rgds George.

[JohnS]

Dnoble

What size is you PV system?  Is it wired into the consumer unit or into a henly block?  Where, in relation to the PV wires is the clamp for your monitor?

The answers to these questions could explain what is happening.  The monitor only measures current, as a proxy for power, and not direction.  You could be in this scenario

PV produces 900w
House consumes 500w
Net export 400w

Switch on downlighters
PV produces 900w
House consumes 500w + 450w = 950w
Net import 50w but you don't know the direction and it looks a reduction from above

Switch on kettle
PV produces 900w
House consumes 500w + 450w + 3000w = 3950w
Net import 3050w   expected increase.

Get LEDs they are good.

[HalcyonRichard]

Hi George,
               To quote "It's not what you've got it's how you use it"   They are 35 watt halogens. My electricity consumption average was 4 kWh per day over the last year.  As I run my buisiness from home - 1 person full time and me 1/2 time this is quite an achievment.  I have tried CFL's and LED's they just don't cut the mustard and are not dimmable. All other lights in the house are CFL's. My gas bill is less than £500 per year.  My mileage is less than 3000 miles per year and I do not own a car(I use my partners). I grow most of my own food and keep chickens. I think it is better to put effort into results and not the means. I think the planet does quite well by me compared to the avearge bod  

Regards Richard

[Lurk]

I had 10 halogen down lighters through my entire house - and over the past couple of years I have been replacing the bulbs as they blow with these :- http://www.simplyled.co.uk/GU10-Dimmable-High-Power-LED-20-piece-SMD-5050-320-Lumens-50-watts-equiv_AWMR4.aspx?1 which are dimable (I don't use dimmers yet may put some in) - the light improvement is fantastic over the 50W halogen GU10 spots that I used to use. The best bit is I don't burn my head now when I stand under the spot lights (low ceilings in my old stone cottage / cave).

Lurk

[M]

I had 10 halogen down lighters through my entire house - and over the past couple of years I have been replacing the bulbs as they blow with these :- http://www.simplyled.co.uk/GU10-Dimmable-High-Power-LED-20-piece-SMD-5050-320-Lumens-50-watts-equiv_AWMR4.aspx?1 which are dimable (I don't use dimmers yet may put some in) - the light improvement is fantastic over the 50W halogen GU10 spots that I used to use. The best bit is I don't burn my head now when I stand under the spot lights (low ceilings in my old stone cottage / cave).

Lurk

Friendly warning - I'd stay away from Cardiff for a while, or else!

I could kiss you!

Been meaning to ask for just such a recommendation all weekend, but never got round to it.

Thanks.

Mart.

[Tigger]

Hmm, LED lights are getting better but ouch, what a price.  I am slowly replacing mine but only once the Halogen ones go pop and even then I have to think long term.

I only have 13 MR16 downlighters in the house.  5 in the kitchen, 2 in the main bedroom, 3 in the en-suite bathroom and 3 in the main bathroom.  Since there's only the two of us in the house for 95% of the time I don't count the main bathroom ones in any calculations.

For the price to 'upgrade' the main 10 downlighers to LED I have to use them for approx 1,500 hours.  Even through winter we're hard pushed to have these particular lights on for much more than 2 hours per day so that's going to take 2 years, or more realistically 3 when I allow for summer time when they never get used at all........

Still, at least I'll sleep better once they're all changed 

[dnoble]

Thanks for the replies. They're only 20w halogens by the way. I did replace some with some cheapo LEDs off ebay a couple of years back with very poor and short lived results. I will retry them if they've improved!
I looked at that Wixkipedia link Clivejo, thanks but completely incomprehensible I'm afraid.
JohnS I dont really follow your example. The B Gas monitor is supposed to measure consumption + it gives an hourly + monthly cost for whatever you're using at the time. I think it's clamped onto the consumer unit (don't know what a Henly block is). I presumed the solar monitor is incidental, I just mentioned it to set the scene. Obviously it'll offset net power consumption when it's sunny + make the running total go down.
What I cant work out is why only the halogen cause it to drop when switched on, the TV, dishwasher, kettle, toater all cause it to jump as you'd expect

[HalcyonRichard]

Hi,
    The monitor measures whats flowing in a wire - this can be generation or consumption. It's vital you know where it is clamped. If you can clamp it on the lighting circuit from the consumer unit you should just read the consumption of the lights(this could diagnose if the halogens are giving a funny reading). If you clamp it on a ring main feed you can measure the "sockets". You could try adding plug in a table lamp(s) to check the meter reacts properly.

Regards Richard

[JohnS]

Dnoble

Have a look at this thread and open the link and pdf.  It should help explain the issue.

http://www.navitron.org.uk/forum/index.php/topic,14551.msg169222.html#msg169222

Remember that your monitor cannot tell whether you are consuming or exporting.  It does not know which direction the current is going.

John