Subnostr

It's interesting to understand what your electricity bill tells you.

Your bill is based on the tariff rate applied to the amount of energy you consume. Tariffs rate could be 50 cents per kWh or tiered.

If we start from the source, homes are supplied with AC (alternating current) at 110V or 220V, depending on the country. If you have solar panels, these generate DC (direct current), which is inverted into AC. AC systems have impedance, which includes resistance and reactance (conductance, inductance).

Each appliances in your home that needs electricity has resistance. Those with lower resistance like air conditioners will draw more current. Incandescent bulbs draw more current than LEDs.

Current (I) is calculated using Ohm’s Law V=IR (or I = V/R). For accuracy Z will represent impedance and the lengthy calculation has cos theta but for simplicity we remain with V=IR

Once you have voltage and current, you can then calculate power, P=VI which gives you in watts (1 horsepower is about 745 watt). To convert watts to kilowatts, divide by 1000.

Energy is how much power you consume over a certain time frame (kWh). This is what your electricity bill is based on, Energy = power x time.

You can then calculate your damage for the month by multiplying energy to the tariff allocated.

Other stuff that might be interesting is that your home circuit is typically parallel circuits, which allows each appliance to receive the same voltage. Circuit breakers protect the system if the current is too high.

I recently had a high spike in the bill so I tried testing the power points if there was a surge, and went to test most of the equipment. And eventually used a clamp meter to test the main panels one by one and found the culprit.

I know this is probably your middle school learning, i taught my nephews this just last year. But it is interesting nevertheless

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Discussion

Robertrobert 1y ago

How did you fix the culprit circuit?

pam 1y ago

it was due to an old air conditioner that was already repaired many times and likely had current leakage, and too low a horse power to cover the area. i had it replace, got one with an inverter that disconnects once the set temperature is achieved. I also tinted the windows to cool down the place faster (its fairly easy to do this DIY and cost 1/10 the price of outsourcing it). This brought down the bill to 2/3 of what it used to be and i hope hit my ROI within 7 months. i also noticed that there is very small current that still flows when the equipment is connected to the plug point even if its not turned on, so i made it a habit to switch off all the circuit when not in use.

Robertrobert 1y ago

You’re an engineer, right?

pam 1y ago

i used to dabble in high freq, not electrical, but it is not complex. I do not have safety gears nor have I figured out where the main grounding port is - so instead of taking the risk of open circuit the pathway, the easier and safer way is to use a clamp meter. You get to narrow down block by block and take down the culprit. These days there are also smart gadgets for plug points and equipment where you can just plug in straight and see if its faulty.