# Forum Home Renovation Lighting  Power Consumption of Halogen Transformer with Retrofit LED bulbs

## JB1

We had 60 Halogen MR16 bulbs replaced with Retrofit LED bulbs free under  the Vic Government Scheme. I think it's ripping off the State Gov, but  if you can't beat them, join them. 
They are 6W LEDs and claim 500lumens, so not too bad but not as good as  Halogen and no where are good as dedicated LED kits I installed at my  previous place.  
We have the old heavy wire wound transformer. I can't remember where I  read it, but I recall reading that the halogen transformer itself  consumes a similar amount of power when running 50w Halogen as they do  for 6w Retrofit LED bulbs. 
Can someone confirm if this is true (in particular with wire wound transformers)? 
Or does it say use 20% of the power to run a 6w LED bulb compared to a 50w Halogen bulb? 
Basically I'm trying to work out the total power consumption of the new lights.

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## OBBob

Good question! I can't answer exactly but I know the old transformers vs the newer switchmode versions will have a higher sanding consumption. There may even be some consumption when the lights are not in use (not sure)?? 
Some info here ... LEDBenchmark - Transformers for MR16 LEDs  
edit - the page I posted suggests a fair consumption even when lights are off.

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## JB1

Interesting read. 
It appears that the power consumption of the transformer drops from 15w to 10w when replacing a 50w halogen bulb to 6w LED. 
So overall consumption drops from 65w to 16w. Still a good saving but definitely not 90% as claimed. 
There is no consumption if the light switch is off. There is consumption if the switch is on but no globe.

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## OBBob

> Interesting read. 
> It appears that the power consumption of the transformer drops from 15w to 10w when replacing a 50w halogen bulb to 6w LED. 
> So overall consumption drops from 65w to 16w. Still a good saving but definitely not 90% as claimed. 
> There is no consumption if the light switch is off. There is consumption if the switch is on but no globe.

  Yes,  good point.

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## Smurf

Not sure if the 10W and 15W figures are accurate but it sounds about right overall. 
There will definitely be a saving, but not 90%. But hey, if you got them for free then that's still a good deal.

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## dinosour

The power draw of the transformer should be constant and not change with load, it's a fixed electrical load

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## Smurf

Put more load on a transformer and it definitely gets warmer due to it dissipating more energy. I've never looked into what the relationship between load and transformer losses is, but more load definitely does dissipate more energy at the transformer.

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