On 12 Jan, 17:26, "Nick" wrote:
I recently got a ac current and power meter and something has become
apparent which makes me wonder if its significantly out of calibration... or
just the type of load.

It seems to measure pure resistive and most other loads accurately,
including those with SMPS like the TV / PC etc.

But try and measure a CFL or indeed any Fluorescent light and it is telling
me it is consuming about double the power it should be.

- The 60 watt circular kitchen lights each consume around 120 watts
- The dual 58 watt (116 watts) fluorescent lights takes approx 170 watts
- the 18 watt CFLs take approx 34 watts
* *In fact the Megaman 11 watt CFL has printed on it 96 mA
* * which is 230 x 0.096 = 22.08 watts

Can anyone explain ?

Is the power not going into the tube
not counted ? *( i.e what the ballast wastes not counted ?)

Thanks,

Nick

Any flourescent light has a power loss in the choke/control gear. If
you check in the OSG for a rule of thumb this is normally taken as not
less than 80% of the rated power of the lamp thus a 100 watt lamp
fitting will consume 180 watts of power or more. Your readings are
entirely ok
(For those with a copy of the 17th edition OSG its note 2 on page 96
dealing with assumed current demand)