Electricity meter size and low voltage?

[ilikethai]

Hello and happy New Year to all!!! First of all, I have a Single Phase 2 wires 220v meter with this number on the face of its plate, 5(15). I have 2 air con (not really using them), big lcd tv, fan, 5 light blubs with 2 turn on at night time, microwave, Hitachi water pump. What I worry the most is my laptop and my desktop which I keep on sometimes 24hrs.

The problem is that the voltage fluctuates throughout the day anywhere from 210v-230v, this is even when not using air con or water pump, but when I turn on just 1 air con I loose about more than 5 volts. I had checked throughly with a handheld voltage meter. The electrcity company wants me to upgrade (buy) a "bigger" meter or a 3 wires meter. I was even told to use 2 meters.

the meter sizes are like 5/15, 15/45 and 30/100 etc., I can't really afford a new bigger meter.

1. Please explain what the size numbers mean.
2. Does meter "size" regulate voltage or how powerful and enough electrcity is?
3. Can a voltage stabilizer be a better way out?
4. Aluminium vs Copper wire, does aluminium makes voltage drops?
5. Does wire size affect drop of voltage? What is the mininum size for Aluminium and Copper wire?

6. Does voltage drop cost money?

thank you in advance,

Ed.

[Crossy]

Ok, firstly a variation of 210V - 230V is quite acceptable, all modern domestic equipment can easily handle a +- 10% variation, i.e. 198V-242V on a nominal 220V supply.

Your laptop likely has a universal power supply that will work from 90V-250V and will be quite happy on your supply. I do suggest you use a good quality surge arrestor in the wall outlet to stop any nasties from lightning or similar getting to your PC

To answer your questions:

1. Please explain what the size numbers mean.

2. Does meter "size" regulate voltage or how powerful and enough electrcity is?

3. Can a voltage stabilizer be a better way out?

4. Aluminium vs Copper wire, does aluminium makes voltage drops?

5. Does wire size affect drop of voltage? What is the mininum size for Aluminium and Copper wire?

6. Does voltage drop cost money?

1. The first number is the calibration current, the second is the maximum rated current, so your 5/15 has a maximum current of 15A (about 3300 Watts).

2. No, and the meters are very robust, but long term overloads above about 150% of rated current may affect accuracy (and you can bet it won't read low).

3. A voltage stabilizer will reduce the voltage variation should the supply go out of spec (below 190V or so) but it does so at the expense of drawing more current which may cause further drop in supply.

4. Aluminium wire needs to be one size bigger than copper for approximately the same drop.

5. Yes, the minimum size needed is determined by the length of the run and the required load current.

6. You are paying for the energy that is warming up the wire so yes, voltage drop does cost money.

[kamalabob2]

The cost to upgrade to a better, larger meter, will pale in the cost you might incur if you "blow out" your meter and have a surge, fire or brown out in your home. Your meter is sized for a village family with nominal electrical consumption. I lived in a row house rental for 2 years with the 15/45 meter. 2 a/c units, major appliances, no issues. But a few houses down an expat had nothing out of the ordinary, for a Farang furnished 2 bedroom house. Two a/c, a water pump, water heater, TV, small appliances, normal major appliances. One day BOOM, POP and all the power went out on the block and he had a fire at his meter and a surge or some major electric malfunction in his modest house. That 5/15 meter service cost him dearly. Depending on who actually signed up at the PEA office, for the OP current electric meter, they might have a modest deposit on the books. If he goes to his PEA office, the actual net cost to upgrade to a 15/45 is nominal, as the deposit is refundable when he changes service or changes address. Crossy did a fantastic job of answering each question for the OP.

[rawhod]

We have a 5(15) meter on our townhouse. in CM. We went to the PEA to enquire about an upgrade to a 15(45) meter and they sent an engineer to assess our system.We had the wrong feed wire from the meter to the house, the wrong size cut out switch, no earthing wire and therefore no earth/neutral connector. They said that if we brought the system up to the correct standard they would fit a 15(45) meter at a cost of near 5,000 baht (I I recall correctly)

We did up date the system but just stuck with the 5(15) meter since it copes with our modest demands.

[IMHO]

As Crossy noted 210-230V swing is normal... and I'll add that 5 volts drop is nothing to worry about at all. If/when your voltage is dropping down below 200V, then you have a problem worth solving

[ilikethai]

Thank you all for the reply. I still do not understand what the first number (5/15) means now I know that 15 times 220v equals 3300 wattts. So if I go with bigger size meter I will have more volt and more steady flow of current?

So what good is a current stabilizer device if it consume more electricity if I'm not getting a stable current in the first place?

Edited April 11, 2014 by ilikethai

[Pib]

The 5A represents the current/amps flow the manufacturer uses to "calibrate/check the accuracy" of the meter since the electric meter installed should be sized to approximate the average current/amps a household draws...and I guess electric meter manufacturers over the years have determined an electric meter operating at approx one-third of its maximum value is best for long term reliability and accuracy of the meter. You wouldn't want to be using any measuring device (which is all your electric meter is) that is always being operated at close to its maximum, continuous operating specs which is 15A in your case. It's kinda like would you want to be continuously operating your car engine at an RPM "just below" its redline region...probably not, because the engine would wear-out (or blow up) much sooner.

Having a bigger electric meter will have no effect in improving your current/voltage levels...that's determined by the electric source feeding your electric meter, size of your electric wires, etc. Your electric meter is only a measuring device.

[Crossy]

So what good is a current stabilizer device if it consume more electricity if I'm not getting a stable current in the first place?

An AVR will ensure that the supply to sensitive equipment does not go outside the safe range. It does that by controlling its output voltage, but it does that at the expense of extra current draw when the supply is low, it's basic physics.

Example.

Your AVR produces an output of 220V, your load draws 10A at that 220V so the load power is 2200W

Assuming the AVR is 100% efficient (they are not).

If the input voltage is 220V then the current drawn from the mains for the 2200W load is 10A.

If the input now falls to 200V, the output maintains 220V (that's what AVRs do), the load still draws 10A (2200W) from the output. Since Power Out cannot be greater than Power In, to maintain the required 2200W at 200V the AVR must draw 11A.

If the supply falls to 170V the AVR must now draw 13A, and so it continues until the AVR reaches saturation at which point the output voltage will start to fall off, or the supply collapses catastrophically and cuts out completely.

AVRs do have their place, we have one feeding our computer UPS, it stops the UPS going on battery when the supply is low which it can be for long periods in the village.

[longball53098]

Crossy, good explanation of the AVR at a low voltage condition. Can you reverse that and explain what happens if the supply is constantly over the supply rating and is at say 237-240 most of the time?

[Crossy]

Crossy, good explanation of the AVR at a low voltage condition. Can you reverse that and explain what happens if the supply is constantly over the supply rating and is at say 237-240 most of the time?

Exactly the opposite, the AVR will regulate the overvoltage down to 220V and draw a correspondingly lower current.

Continuing my example:

If the supply rises to 260V the AVR maintains its 220V output, the load still draws 10A, but the input current is now about 8.5A.

[longball53098]

Great thanks for the info as always