Jan’s blogs about life

Here’s an interesting post in the BU4 community forum about electricity / energy power saving device. I have come across people selling these so called energy saving devices but was not sure of its effectiveness. With the escalating price of petroleum leading to higher cost of using electricity, we can be quite tempted to buy or install some device that would somehow reduce our electric bill. However these devices are over hyped and this is one myth worth busting.

Has anyone tried/used any of the electricity saving devices out there?
Angela Ong

Reply by Alex Thing:

Don’t know about the first 2 question, but can provide some info about the myth of certain power saving devices.

Many ppl are selling so call energy saving devices that can help you to save your Tenaga bill. Please note that “energy saving” and “tenaga bills” are 2 different things.

Typically they will use an Ammeter (an instrument for measuring electric current in amperes) to measure the electric current drawn by your appliance at home. To make the trick successful they will normally ask you to switch on your air-cond. Air-cond is essentially a “reactive load”,( to make it simple, just take it as appliances that have electric motors in it.) and the biggest load in a normal home. Loads like this draw a lot of electricity but only a portion (about 75 to 85%) are utilised to carry out the work. This is because of the out-of-phase of the current and voltage angle in reactive loads. Commercial/industry users have 2 meters. One to measure the kW which is the actual “work done” or actual power utilised productively, and one for measuring the kVAR –which is the “wastage”. Tenaga will bill them on both meters. If the wastage is too high as a percentage compared to the actual “work done”, tenaga will penalise these users for their wastage.

So it is every commercial/industry user’s interest to improve the efficiency of their electical system/appliances. To do this, they need a device called “capacitor” to counter the motor load. Capacitor effectively brings down the reactive power in motor load immediately and thus reducing the electric current drwan by it. During this, the actual work done by your air cond (ie the productive part of it) still maintain the same. So, after plugging in the capacitor bank into your socket or any part of the wiring system, the sales person will show you the reading in the Ammeter drops immediately. Definitely you are now conviced that you can save money using it.

You are right. That capacitor bank/device indeed reduces the current drawn by your appliances/ aircond.

But…. tenaga did not bill you on the wastage / reactive power. Remember, Tenaga only gives you 1 meter, right? Domestic users are NOT BILLed for the reactive power. Tenaga only charge you the “actual work done” part. The “wastage” has been priced in to your unit rate when they came up with the formula on how to bill you.

So, the conclusion: ….. You save some energy, but not the bill. It is good for the environment anyway.
The bottom line is, residential don’t need that… industry users — almost all of them already have that incorporated into their switchboards…. so unless you are a not so big commercial users without a capacitor banks in your switchboard….