Monthly Archives: July 2012

High-efficiency Work Lights

I love tinkering and building things, especially after work. This means working indoors, and good light makes for an enjoyable, productive and safe workplace. Usually it is better to have multiple sources leading to less shadows but sometimes you need one very strong light source. Just like for bulbs that are too small, finding efficient replacement for bulbs that are too large can be hard. Fortunately I found this CFL bulb by Ecosmart that for 68 Watts generates more light than a regular 300 W fixture.

EcoSmart 300W CFL Bulb

The bulb is quite big – almost comically big – as compared to a regular bulb, as you can see in the picture below. Make sure you are planning to put it in a fixture that will fit it!. But it gets the job done and I can use it for a handful of hours without blowing my daily energy budget.
300W CFL Work Light. Yes, I have kept one incandescent bulb for nostalgia purposes and reference pictures like these.Of course, as with any CFL, one has to be very careful not to break them and to recycle them appropriately because of their Mercury content.


I would love to hear stories of others making their work lights more efficient. I have seen, but haven’t tried these other work lights which are LED based but because of the cost and form factor – I just needed something to put in a bulb socket.

Measuring power use on 240V appliances

In the USA large appliances like clothes dryers or electric car chargers are built for 240V. I happily have used the Kill-A-Watt EZ for simple measurements, but 240V appliances can’t be measured through it. The TED5000 I have measure whole-house electricity usage, but I wanted to update my chart of where power goes in my house (electric power, that is). I want to get an updated picture of what % goes to heating, fridges, etc.

The TED5000 could be a great option but having to install a new MTU and CTs seemed complex, especially once it comes to aggregating the data into only one gateway. I thought splitting the 240V lines and feeding one live/neutral pair in a Kill-A-Watt… but not knowing more about the internals of the Kill-A-Watt I felt I may introduce unnecessary safety risks.

Instead, I built my own portable 240 Volt power meter:


  • Get a Dryer cable (there are differrent models, older 3-prong and newer 4-prong plugs with separate ground and neutral connections. I got the type of cable I needed). Example
  • Get a surface-mount receptacle for the same type of cable you have. Example
  • Get a EKM DIN-Mount power meter

With these elements in hands I assembled a simple 240V “extension cord” that has a remote display to measure the power going through it. The remoteness of the display (a design idea from the Belkin Conserve meter that is otherwise useless) is useful especially with 240V appliances where the outlets are inaccessible, behind heavy stuff, plugs are huge and hard to maneuver in cramped conditions, and you generally don’t want to be messing around with them.

 The assembly was simple. I got lucky since the CT of the EKM device fit nicely in the surface mount box with no stress to case or cable.

Since it measures current going only through one live lead, the actual power is twice the displayed value in the meter. Unlike many other countries where the use of 2 out of 3 phases at 120deg phase is common, in the USA higher-voltage appliances are powered with two counter-phase live lines of 120V each, so getting the real power used is a simple matter of multiplying by 2 instead of by square root of 3.

This meter is handling 240V with high currents so it is important to do a careful job if you decide to build your own. Doing 240 V in Canada is illegal if you are not an electrician and you can void your house insurance. You can hurt your loved ones, yourself, or your property if you don’t know what you are doing (this is true for everything in life, however).

The EKM meter gets the current reading from the ring ammeter in the outlet, and reads the voltage through a couple of extra cables.

Here is the end layout before getting the EKM meter and cable into casing and protective stuff:

DIY 240 V power meter

The meter reads cumulative kWh so you need to keep a logbook of when you started and stopped measuring what. It tracks kWh to 2 decimal places so it’s more than precise enough for the use we are giving it.

Portable vs Breaker Panel metering?

I like the meter I built, for its portability, simplicity, and that I can lend it to friends.

But after getting some basic measurements I am considering installing the EKM as an add-on to my breaker panel. This will allow me to periodically re-wire the CT onto different circuits. I may decide to invest in a better meter – EKM has a very compelling product line– , but I have pushed my electricity consumption so low already that I would need to expect to discover significant in the data obtained in order to recover the cost. After all, the basics save most of the money.

But if you are starting the process I went through improving your house’s electricity efficiency from the beginning, or you want to discriminate between appliances such as electric cars, and you care about measuring stuff, I would highly recommend installing one of EKM’s smarter meters near the breaker box and investing in a couple of clamp-on CTs. If you don’t care about fine-grained measurement just follow the main improvements and use your bill to track improvement.

Feel free to leave comments & questions below!

Replacing 40W Spot Bulbs with 6W LED Spots

I’ll do a couple of quick posts to share how I have improved efficiency in situations/fixtures that require non-standard or hard-to find bulbs.

40W Spot bulbs

The 40 W spot bulbs are used in recessed and small table lamps. With my adapter + bulb contraption, the spot light even looks nice (IMO)These are hard to find in CFL because of their small size. I couldn’t find a direct replacement that had enough lumens to be any good or had a good temperature.

What I did is I bought some LED GU10 bulbs that are smaller. The GU10 plug looks like two fatty prongs that are intended to be twist-locked in place (see the pictures). I then got a ceramic adapter that has a normal bulb screw on one end, and a socket for GU10 plug on the other.

Despite this looking weirdly "long", the overall length and diameter is exactly the same as those stubby 40 spot lights.With that, I could adapt some EcoSmart bulbs and they worked great. Here they are in HomeDepot but with a different packaging than I had them (I bought them in little cardboard boxes, and Amazon doesn’t carry them as I write this). I wish I hadn’t given away the old normal bulb to give you a comparison image – when assembled, the picture of the combined bulb+adapter to the right looks disproportionately long, but the overall length is less than a 1/8th of an inch longer than the original.

 The adapters are not cheap (I got them at Amazon for $5.95) but worth it. These lamps tend to spend a couple of hours on in the winter. I got rid of 2 bulbs, so 2 x 40W= 80 W went out and got replaced it with 2 x 6 W = 12W. It repays itself in 5 years with calculated guesstimates.

Finding a bulb that I liked wasn’t that easy – the Philips brand was both too bluish,weak and had a weird, diffuse shadow. These are brighter but 3000K. I would have preferred 2700K for a mellower, warmer look. Still these look great and given how much they are used definitively worth it.

Replacing Halogen Recessed Lights with LEDs

For my house, this LED bulb became the star as the house has a lot of small recessed lights in high-traffic areas.

All in all we have replaced 34 50W halogen bulbs (that’s 1700 W spread between the kitchen, stairs, hallway and main bedroom) with 29 of 7W Philips LEDs (to 203 W). Just swapping the kitchen lights and hallway/stairs lights made a measurable difference. In this area of the world, days are short in the wintertime and you need lights on until 9AM and from around 4:30 PM. The halogen bulbs required 8 TIMES more electricity.


I liked these Philips bulbs after trying others because of:

7W LED Bulb from Philips

  • Temperature: 2700K – a nice, warm color suitable or ambient lighting.
  • As bright, or maybe brighter, than a 50W halogen (I’ve done the experiment and folks can’t tell them apart without seeing the actual bulb)
  • Only 7W
  • Dimmable
  • The 3-element LEDs actually create a nice shadow pattern against walls, making the light a bit more diffuse
  • When installed, they look nice, even if a bit UFO-ish (but I don’t care much)
  • They are not too expensive compared to other LEDs in the same factor (I’ve found them between $26 and $22 – I mostly got them at Home Depot)
  • I also used the opportunity to remove some bulbs that were making lighting too uniform. Now light follows social function of the space better in the family room.
Philips 418426 7W

For my “good” goal of 16 kWh/day, having a kitchen circuit with 10 x 50W for 3 hours was blowing 1500 kWh – that’s just one room in the house eating up 10% of the energy budget!

What’s the Return of Investment?

LED bulbs are not cheap and it’s not where you start with an energy reduction effort, but I saw an immediate difference in the electricity use in the bills. Since these are recessed lights, having kill-a-watt meters is not possible (how long until in-wall switches and outlets report their use via wifi?) so there is a little bit of interpolation going on.

I spent a lot of my ‘efficiency’ budget on these bulbs (once I had improved house thermal insulation, and done other basic improvements). It will take around 10 to 15 years for a recovery on the investment assuming the bulbs live their advertised life and assuming some 3hs of daily use. It would take 23 mega Watt-hours to keep the halogen bulbs on, and they would need many many replacements along the way. With these LEDs it’s buy once and 3200 kWh using the same assumptions. Even though my energy sources are now somewhat renewable, they still have a carbon footprint larger than zero, so using less Watts is still good beyond the money.

Remember our economy of fossil fuels is vastly distorted due to externalizations and subsidies so the money-cost of burning coal or gas is quite irrelevant to calculating the real ROI of the bulb. Of course the cost of the bulb itself is lower than it should be too, because of the equally artificially lowered costs in its manufacture and transport – but the difference between the manufacture of different sorts of bulbs (CFLs, LEDs) is so little when done at scale so that difference evens out if we are doing comparisons between bulbs (comparing these bulbs to light from candles made of beeswax in your own backyard is a very different exercise, but I don’t have that luxury). I haven’t seen a great supply-chain analysis of the material, energetic and human costs involved in making and transporting different bulbs; including data for fossil fuel and rare-earth elements, so a lot of externalizations are hiding there; but the ones that I have seen lead me to believe it ‘makes sense’ to go with the LEDs in the larger scheme of things – their 5x + longevity alone offsets a lesser increase in complexity and reliance on mercury. It is a complex landscape with no map…