Low Energy Lightbulbs - Consumes 30w not 11w

upthehammers

I've got an electricity monitor from my utility company which shows me that my 11w. CFL lightbulbs are consuming 25 -30 wattts each.

I've waited to see whether this is a warm-up issue, it's not, and aslo compared different bulbs and totted-up using several simultaneously.

The results are the same - all my bulbs are using 2-3x what they should.

I've searched online in vain and can't find out why this is. Anyone got any ideas?

espresso

Utility company supplied energy monitors are inaccurate when measuring low loads. They are inaccurate because they are not connected to the supply and simply assume what the mains voltage is when calculating the wattage from the sensed current. The plug in type monitors are much more accurate.

Trust the CFL lamp NOT the energy monitor!

upthehammers

Thanks Espresso. But I don't understand, the monitor is connected to the supply, its got a clamp round the incoming cable. Also, it appears to monitor the correct usage of other low-use items, like some led lights at 10 w.

rogerblack

upthehammers wrote: »

Thanks Espresso. But I don't understand, the monitor is connected to the supply, its got a clamp round the incoming cable. Also, it appears to monitor the correct usage of other low-use items, like some led lights at 10 w.

For various technical reasons, they are inaccurate for some loads.
http://www.ebay.co.uk/itm/Energenie-ENERGY-SAVING-POWER-METER-SAVE-MONEY-/221292961343?pt=UK_Sound_Vision_Other&hash=item3386169e3f

Or similar is far more accurate for individual loads.

espresso

upthehammers wrote: »

Thanks Espresso. But I don't understand, the monitor is connected to the supply, its got a clamp round the incoming cable. Also, it appears to monitor the correct usage of other low-use items, like some led lights at 10 w.

It is not actually connected the the mains supply - the clamp is a simple transformer to sense the current drawn, so the monitor can only calculate wattage from this input current alone. Different devices present a different type of load and this also affects monitor accuracy. Check them using a multimeter or a plug in type meter with physical connections to the mains supply.

matelodave

Low energy CFL bulbs don't consume power like a heater or toaster or even an LED. They are reactive like fluorescent tubes and even washing machines & so the current & voltage are not in phase so something called power factor comes into play. You would need to measure using a plug-in monitor which actually measures the consumption of the device directly and not via the magnetic field that's produced which is how a clamp on device works.