Wesley's Tool-Box

Having a smart meter giving real-time power consumption data provided a lot of insights for my home. The baseline load when everything is idle is about 80W, and the refrigerator running at full power adds 90W to that. So when I noticed that more than 300W were being used during the evening hours even with the TV turned off, I had to track down what the culprit was.

It turned out that the sole reason for this uptick was the lighting. Fluorescent lights in the living room and the study room were turned on for several hours every day and contributing much to the total consumption. Knowing that LED lights were more efficient and that the price has come down a lot recently, I decided to make some major investment.


As with a lot of apartments in Korea, the typical type of lighting installed was PL compact fluorescent lights, or FPL for short. It uses 4-pin 2G11 socket and has external ballast. Lots of replacement methods exist - lamp-only, ballast + lamp (socket is kept), or total replacement. As the lamp-only method is simplest by far and not much more expensive than replacing everything, the choice was obvious for me. I ordered the relevant LED lamps manufactured and sold by TopLux of Korea which were on sale - 23W version cost about KRW 21,000 (US$17.50) and 15W one, KRW 14,000 (US$11.70). Here is how they stack up with the existing FPL lamps.


According to the specifications, the LED lamp consumes about half the power while putting out about 85% of total light, or luminous flux, compared to the similarly sized FPL counterpart. This is indeed quite an increase in efficiency if it delivers. Visually, one side of the lamp is taken up by a long heat sink and uses the same four-pin layout. The pins themselves are simply round, not dimpled in the middle like the FPL it's replacing, so I suppose it won't "hook in" quite as well.

My home isn't particularly wasteful when it comes to electricity spending - it rarely exceeds 200kWh per month except for hot summer months. Still, I wanted to see the real-time usage to make further optimizations. After browsing through myriads of metering solutions, both domestic and abroad, I settled on a particular product sold by Seojun Electric.

Officially called "Smart Power & Charge Meter" model SJPM-B70 (I'll simply refer to it as "smart meter" hereafter), it connects to the main power line going through the primary circuit breaker inside the house. Once installed, it constantly measures and stores the power consumption data. This can then be accessed in real time by a smartphone via Bluetooth technology.


The main thing going for this product is its cost and simplicity. It only costs KRW 42,000 (US$35) online, not much more than the power monitors you plug into an outlet. And you merely need to hook the sensor and the power plug into the right place to get it working - no further maintenance required. Instructions on how to do that are shown with diagrams in the included guide.

You also don't need to sign up for anything as the data stays in your house, fully under your control. As I don't need to have my consumption data shared and analyzed over the internet cloud, this was actually a plus for me. And in case you wanted to show that you have this smart meter installed, the package provides two blue stickers to let you do just that.