# Current through a 220V line

Thread Starter

#### kahafeez

Joined Dec 2, 2008
150
Hello, i live in Asia and here the AC voltage is 220V... can anyone please tell what is the value of current ??? according to my understanding its 10Amperes. but i am not sure.... plz help...

#### alim

Joined Dec 27, 2005
113
Your question is vague. Wht current are you asking about, is it from the power supplier, or is it your inlet demand that you require. For the first see the power company , for the second your installation tech would tell you.

#### studiot

Joined Nov 9, 2007
5,003
The current drawn depends upon the power rating of device you connect to the supply.

The voltage is always fixed at 220V.

You cannot specify both current and voltage at the same time.

The current is mostly the power divided by the voltage = P/220 in amps.

So 10 amps corresponds to a 2200 watt (2.2 KW) device.

#### alphacat

Joined Jun 6, 2009
186
To be more correct, the current drawn from the power plant is S / V.

Thread Starter

#### kahafeez

Joined Dec 2, 2008
150
thanks everyone.... i wanted to ask about the current supplied from the power company.... and i've come to a conclusion that the current's amount is not fixed... it depends upon the appliance.... righto ???

#### loosewire

Joined Apr 25, 2008
1,571
Kahafeez, Do you have curcuit breakers or fuses in your panel,maybe I can help.
Do you have a.c.(air condition) in your house. It will help you understand more
If you answer.

Last edited:

#### studiot

Joined Nov 9, 2007
5,003
it depends upon the appliance.... righto ???
You're getting there.

If you have more than one appliance, the voltage stays the same (220). You add the together the currents for each appliance to get the total current.

So 20 x 1/2 amp light bulbs make 10 amps.
2 x 5 amp electric fire bars makes 10 amps
1 elctric fire bar plus 2 light bulbs makes 6 amps.

and so on

#### studiot

Joined Nov 9, 2007
5,003
The maxim current you can use, will depend from the type of contract you have signed with the power company. I have a 3KW contract and 220 volts @ 50 Hz single phase. Maximum current I can use is 15 Amps (since there is a 10% allowance)
After that the breaker will cut me off.
That's an interesting concept, where in the world does this apply Alberto?

Breakers in the UK are only there for safety purposes, there is not such contract limit. If I draw more I pay more.

#### b.shahvir

Joined Jan 6, 2009
444
studiot, I am pretty sure that if you read more carefully the contract you have signed with your power company, you will notice that a power limit is there. Very likely not in Ampers but in KWatts.

Think logically, if no limits apply, the power company will need to use huge wires for every houses, also for the one that will light only a few candels bulb for few hours a day.
The main intrinsic limitation to the maximum current you can draw is with the cable size that connect your house to the nearest distributing sub-station.

You will pay, as I do, KWh consumption, which is ralated to current but not the same thing.

Answering to your question, I am living in Italy.

Alberto

I also do agree with Alberto. Although I'm not aware of any contract demand, in my case I would have to intimate the electric company before hand if I need to increase my connected load! This also applies to change in type of supply system availed for, single phase or three phase.

#### studiot

Joined Nov 9, 2007
5,003
Under the Electricity Acts, you have to state the expected maximum demand. The supply company then has an obligation to supply this.

Of course they can charge extra for huge MD, although they often offer discounts for lowering your MD or timing it out of peak hours.
If it was ridiculously high you might also end up paying for extra cabling in the street - not a cheap prospect.

If you keep within accepted norms a domestic supply will be protected by a 100amp fuse, whatever size of supply you anticipate. At Uk voltages this = 24KVA.

#### alim

Joined Dec 27, 2005
113
Where I am we pay what is called 'installed capacity' , i.e. your main switch capacity times the supply voltage, which amounts to what Alberto has said.

#### R!f@@

Joined Apr 2, 2009
9,647
That's an interesting concept, where in the world does this apply Alberto?

Breakers in the UK are only there for safety purposes, there is not such contract limit. If I draw more I pay more.
Maldives !!! DUH!!
We have like 32A max for a single phase

Rifaa

#### studiot

Joined Nov 9, 2007
5,003
Some instantaneous water heaters (for showers) are 8KW by themselves.

You still have to apply what our regs call 'diversity' to keep under 24KVA.

That is you won't have the shower, electric cooker, all the lights, heating, all going at once. If you do all that it can be very easy to clock up the 24KVA.

#### studiot

Joined Nov 9, 2007
5,003
Yes I think some showers produce a lot of steam, however these are the values on the rating plates.

The Germans use the between phase (415) voltage for this to reduce the current draw.

They require special wiring and cannot be plugged into an ordinary 3KW socket. Similarly cookers, hobs etc have too high a rating for ordinary sockets. We do no have many air conditioners in the UK but these could also need this type of supply.

#### Wendy

Joined Mar 24, 2008
21,840
Wish I could say that about Dallas. We peaked at 103°F (39°C) yesterday, and have had about a month of this weather with some minor breaks. Here 2 phase 220VAC is the norm, with each phase providing several 120VAC wall outlet legs. The 220AC is saved for the heavy appliances, such as the stoves, laundry dryers, and AC. Won't swear to it, but I think we have a 100A breaker in the box, mostly for total house disconnect. Each leg has smaller breakers, 15A 120VAC being the usual, and at 15A most of these breakers actually trip early, say 12A or so.

#### b.shahvir

Joined Jan 6, 2009
444
Here 2 phase 220VAC is the norm, with each phase providing several 120VAC wall outlet legs. The 220AC is saved for the heavy appliances, such as the stoves, laundry dryers, and AC.

I think it must be single phase 3-wire system (2 hot legs & 1 neutral). This might be derived from the three phase distribution systems which is then segregated by pole-mounted drum type single phase transformers, the secondary of which is single phase 3-wire type.

220VAC is available between the outer 2 hot legs (for heavy loads) and 120VAC is available between either hot leg and the centre neutral wire. When one says 2-phase system then it would mean the 2 phases are 90 elec. deg. out of phase w.r.t. each other. Also, the neutral wire would carry a continuous out of balance current of √2 times the current in either of the outer hot legs...and as such this might not occur in the case you mentioned above! A single phase 3-wire system neutral carries current only when the loads between outer hot legs and neutral wire are un-balanced and not continuously as is the case in a 2 phase 3-wire system.

Regards,
Shahvir

#### Wendy

Joined Mar 24, 2008
21,840
I think it must be single phase 3-wire system (2 hot legs & 1 neutral). This might be derived from the three phase distribution systems which is then segregated by pole-mounted drum type single phase transformers, the secondary of which is single phase 3-wire type.

220VAC is available between the outer 2 hot legs (for heavy loads) and 120VAC is available between either hot leg and the centre neutral wire. When one says 2-phase system then it would mean the 2 phases are 90 elec. deg. out of phase w.r.t. each other. Also, the neutral wire would carry a continuous out of balance current of √2 times the current in either of the outer hot legs...and as such this might not occur in the case you mentioned above! A single phase 3-wire system neutral carries current only when the loads between outer hot legs and neutral wire are un-balanced and not continuously as is the case in a 2 phase 3-wire system.

Regards,
Shahvir
You're right, it was a brain fart on my part. The term used is split phase electric power. You have to love Wikipedia.

#### b.shahvir

Joined Jan 6, 2009
444
You're right, it was a brain fart on my part. The term used is split phase electric power. You have to love Wikipedia.

Brain -farting is a modern day disease . Thanx for the link anyways.

Regards,
Shahvir