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[burakkucat]

Just wondering if someone could perform the experiment with one LED "bulb" and two DMMs -- one in series with the device and the other in parallel -- measuring current and voltage? 

[oldfogy]

Just as a matter of interest if anyone is interested, I recently saw Digital Multi Metres over on Ebay for under £3 inc P&P
http://www.ebay.co.uk/itm/Mini-Electric-AC-DC-OHM-Voltmeter-Ammeter-Multimeter-Meter-Multi-Tester-MF-110A-/400797651822?pt=LH_DefaultDomain_3&hash=item5d5166d36e

In fact it looks the same type as the one that has been in my tool box for about 15 years.

Edit:
link changed

[sevenlayermuddle]

Just wondering if someone could perform the experiment with one LED "bulb" and two DMMs -- one in series with the device and the other in parallel -- measuring current and voltage? 

That would only tell us the VA, not the power.  Hence why c6em's question re PF.   Would still be of interest, mind.

Worth stressing above all though, since the demise of 'proper' light bulbs, I pay more interest to the luminous flux, expressed in lm, regardless of wattage.

Another important parameter, largely unique to LED bulbs, is the beam angle, which is often quite narrow.   Many LEDs contrive to 'throw' all the light forwards, away from the base.   For a downwards hanging pendant that may be well as it shines onto the floor and walls but, for an upward facing bulb on an external wall lantern, it just lights up the sky.

[oldfogy]

That was the problem with the ones I bought, they were 6000lm +/- and just far to 'white' whereas the 2300lm (also listed as either cool-white or warm-white) give a much warmer looking light.

If no one else offers up the PF, then I will do it tomorrow with one of the 5watt LED lamps I have, but as said in my post above my multi metre is well past it's sell by-date and I wouldn't rely on it's accuracy for such fine readings so will not be offering to do that.

[c6em]

My reason for asking the pf...

The current taken will depend on the VA rather than the Watts
It is the current squared which is the loss/heat maker in transmission and generation.
So VA is of more interest than watts to generators of power and it will always be larger than Watts.
A 50 MW generator would typically be specified as operating at 0.8 or 0.85 power factor.

Indeed there are some exotic stuff that runs at zero power factor - so the KW is zero but I can assure you the current certainly is not.  So a KW meter would read zero while a VA meter would read the true 'VA power' being used.

If we are moving towards a point where the aggregate domestic consumption is at a power factor significantly less than 1 - then we could see domestic electric meter and charging policies changing such that it is metered by KVAhr used and not KWhr....as being a more accurate reflection of the current being drawn.
This is indeed how the big industrial user have been charged for umpteen years.

[sevenlayermuddle]

That was the problem with the ones I bought, they were 6000lm +/- and just far to 'white' whereas the 2300lm (also listed as either cool-white or warm-white) give a much warmer looking light.

If no one else offers up the PF, then I will do it tomorrow with one of the 5watt LED lamps I have, but as said in my post above my multi metre is well past it's sell by-date and I wouldn't rely on it's accuracy for such fine readings so will not be offering to do that.

Colour is a separate measurement from lm. 

If your energy monitoring devices are half decent they will probably be switchable between 'VA' and 'watts'.   Mine are.

I would strongly recommend not attempting to measure mains current and voltage  unless you really know what you are doing, and are qualified.   I have a BSc in Electronics & Electrical Engineering.  But that was a while ago, and even with my Uni' degree still I'd think long and hard before going anywhere near mains voltages with my own DMMs....   

Note for example I am not volunteering here, even though I have plentiful test equipment.   

[sevenlayermuddle]

So VA is of more interest than watts to generators of power...

Agreed, wholeheartedly.

But watts are what we are billed for, or more accurately watts integrated with time, ie energy, or Watt Hours.

A low power factor is bad for the environment and bad for the supplier's bank balance.   But the end-user consumer, assuming he has no real interest in the Power Company's well being, can smile smugly and disregard the VA, as he pays just for the Watt Hours.   

In any case, OF is discussing Watts here, not VA.

[oldfogy]

In any case, OF is discussing Watts here, not VA.

Very true.

However just to point out, I started work in 1964 as a apprentice electrician and worked most of my time as a electrician and mainly running my own very successful company, although as with most things in life, the grass always looked greener on the other side so I did deviate a few times from my chosen profession, but always ended up returning to the job I knew and did best.

Colour is a separate measurement from lm. 
Yes I was just trying to point out to anyone who was interested that the colour 'lm' can be a very important factor when deciding which lamp to buy.

[guest]

But the end-user consumer, assuming he has no real interest in the Power Company's well being, can smile smugly and disregard the VA, as he pays just for the Watt Hours.   

You may pay for watts but you can't disregard VA (PF) as you'll find most switches have a far lower current rating when dealing with inductive loads.

They have a tendency to weld themselves closed when you exceed 500VA at a PF of 0.7-0.8 - you'll usually find a seperate inductive load rating in the (very) small print.

[sevenlayermuddle]

I plugged one of these 7W leds into a table lamp, fed from my power monitor.

The monitor has a crude resolution of 1W, no fractions.   It alternates occasionally, between 6W and 7W, thus suggesting that the bulb's 7W rating is probably spot on.

Switched to VA it reads 12VA, thus suggesting that the marked 60mA may be steady-state after all, with a pf of circa 0.5-0.6.

[sevenlayermuddle]

You may pay for watts but you can't disregard VA (PF) as you'll find most switches have a far lower current rating when dealing with inductive loads.

They have a tendency to weld themselves closed when you exceed 500VA at a PF of 0.7-0.8 - you'll usually find a seperate inductive load rating in the (very) small print.

Or at least, a disclaimer 'do not use with inductive loads'.

My favourite was a plugin timer switch, that I came across in Tesco a while ago, I planned to use it to make Dad's flat look 'occupied' when it wasn't.  It called itself something like a 'Super Green Timer Switch', and was displayed in bright green packaging.   It was so green in fact, I nearly decided to buy one for all my friends... until I read the small print, 'not for use with energy saving bulbs'.   

[guest]

I looked in all of the "high street" DIY/electrical places around here and not one timer switch was rated at over 2A inductive (most were 1A). In terms of CFLs the timers don't like the start-up surge which fluorescent lighting has.

Edit - the workaround I use for inductive loads is to use a timer/switch to switch a relay on. Much easier to find relays which cope with inductive/capacitive loads than it is to find switches, strange old world at times

[sevenlayermuddle]

One device I'd like to find is a combined timer and dusk/dawn switch.   There are plenty for sale, but the 'timer' part just refers to the on-time.

In my case, it's for the garage wall lantern and I want it on after dark but no matter what time it comes on I want it off again around than 11pm, to avoid annoying the neighbours (and myself).   And of course, it wants suitable IP rating.

You would think that would be a common enough want, but I have been unsuccessful.   Currently have a timer inside the garage, and separate daylight sensor outside.