Need a Formula for household electrical items

[jpanhalt]

After doing all of the adding of individual power needs, remember they are not likely to be all turned on at the same time.

As a reality check, take your electric bill, which is probably in KW-H or equivalent, divide by the number of days for average per day, and divide again by your estimate of daily usage (many people would assume electrical usage goes very low for 6 to 8 hours per day) to get an average per "waking" hour. That doesn't give you peak needs, but it can help to keep you from buying a generator that may be way too big.

If you are really into torture, you could take the readings directly from your meter every day, average them, calculate peak, minimum, and do whatever statistics suit your fancy. John

 

[mneary]

You could also buy a "Kill A Watt" (see ebay) meter and measure the actual needs of some of your loads. I don't know if they sell a UK version...

 

[Super_voip]

Items with motors need a lot more power at turn on as well, or at least can. So long as the frige and washing machine weren't running at the same time, it may be possible to use a 2000W generator. Be careful with the claimed output as it is usually peak power. I've used the "Kill A watt" and the siliconchip kit, the kit is better. Mainly due to the 3 decimal points on the display, it is a lot quicker in getting some sort of readable power used displayed than the "Kill A Watt" think about a device which may only use 1-10 watts for most of the day and the smallest unit for kilowatt used on the "Kill A Watt" is 100Watts. Buy a larger 2.4 - 4 KW generator.

 

[bryan1]

Just be carefull with your inverter purchase and most cheap ones are only mod-sine which aint worth a piece of crap in my book. I lashed out sometine ago and bought a 3kw pure sinewave inverter from Kipoint. They do advertise on ebay but I bought mine directly off them. I use this inverter in my shed and about the only things it wont run is my caddy welder, 2-1/2hp aircon and sometimes my big lathe due to the startup surge exceeding the 9kw rating of the inverter. I set my bridgeport up with a VFD and new 2hp 3 phase motor and now I can run the mill off the inverter with no troubles. I do recommend the kipoint inverter 1. for pricing and 2. I haven't had any problems with mine in near 2 years.

Cheers Bryan

 

[Flex]

Is there a Formula for calculating household electrical items?

I was thinking of buying a generator but I need to know how much electricity all the appliances use so that I can get the right generator for the job.

I have all the manuals for each appliance which give how much power each appliance uses.

I do not know how much power a combie boiler uses if anybody knows that information can you please share that information with me.

One way you can do so is looking at your panel(the main circuit bakers) to find out how many amp's it is, maybe about 100 amp or so. then take a look at your power bill.
the power company charges you by the kWh, figure in the total kWh per-day and that is you daily usage.
Over sizing the generator for more kW is good for those appliances/tools that can take up more power.

But this sizing of the generator/math should be based on the max power the house can use, this is so you can use other tools that say a contractor may use.

Also keep in mined that a residential home has 2 phases to power a range/oven, water heater, dryer, A/C unit, Heater. so you would have to ether buy a 2 phase generator or get 2 generators 1 phase.

I hope that helps...

 

[Nigel Goodwin]

One way you can do so is looking at your panel(the main circuit bakers) to find out how many amp's it is, maybe about 100 amp or so. then take a look at your power bill.
the power company charges you by the kWh, figure in the total kWh per-day and that is you daily usage.
Over sizing the generator for more kW is good for those appliances/tools that can take up more power.

But this sizing of the generator/math should be based on the max power the house can use, this is so you can use other tools that say a contractor may use.

Also keep in mined that a residential home has 2 phases to power a range/oven, water heater, dryer, A/C unit, Heater. so you would have to ether buy a 2 phase generator or get 2 generators 1 phase.

I suggest you try filling your location in, as what you've posted doesn't apply to most of the world.

 

[Flex]

I suggest you try filling your location in, as what you've posted doesn't apply to most of the world.

Sorry from the US,

BTW: what is different? besides the voltage..

 

[Nigel Goodwin]

Sorry from the US,

BTW: what is different? besides the voltage..

Most of the world doesn't use your strange 'two phase' system, electricity is distributed as three phase, with only a single phase and neutral being provided to domestic premises. Commercial premises can have the full three phase supply, giving 440V.

 

[saturn1bguy]

Most of the world doesn't use your strange 'two phase' system... only a single phase and neutral being provided to domestic premises.

Not quite.

In the US the single phase isn't supplied to any residence directly, but sources a nearby center-tapped transformer (for one or several homes), which delivers both legs and the center tap (neutral) to the home. And ground is tied to neutral at the transformer or the respective home's meter. Which means at least 3 conductors deliver power to a home.

Here in the US residential power is 120V/240V, with the lesser voltage being referenced to the center tap. (This is what some people confuse as "two-phase.")

Three-phase power at the user end varies in output levels, depending on what's needed. Most common here commercially is 120V/208V.

 

[arrie]

Just as a kink in the question.

Are your stoves not run from 3-phase power in US?

 

[rjvh]

Just as a kink in the question.

Are your stoves not run from 3-phase power in US?

The gas ones not

Robert-Jan

 

[Hero999]

The US doesn't use a two phase power system, the correct term for the 120-0-120V system is split phase.

 

[saturn1bguy]

Just as a kink in the question.

Are your stoves not run from 3-phase power in US?

Nope.

Those that are electric use 240V (the split-phase system I described earlier). The rest use natural gas...

 

[arrie]

I was just wondering.
Our electric stoves here in SA is 3-phase, that would mean, either they bring three phase into our houses, or have to somehow make up 3-phase power from combining single phase somehow, then again, maybe only 3-phase is brought in, and that is somehow split up to provide the required 3-phase and various single phase connections.

Everything I said is under correction, don't take me to book on it, I have not enquired about it.
Just a statement by Nigel made me wonder how we're so different, then again, this is SA, almost everything is different to the rest of the world.

No need to worry about it though.

 

[saturn1bguy]

Our electric stoves here in SA is 3-phase, that would mean, either they bring three phase into our houses, or have to somehow make up 3-phase power from combining single phase somehow, then again, maybe only 3-phase is brought in, and that is somehow split up to provide the required 3-phase and various single phase connections.

SA = South Africa??

If you have 3-phase appliances, then I'm sure it's brought into the home that way, four or five wires, depending on whether ground is generated at your meter. The higher voltage would be between phases, the lower voltage between any of the three phases and neutral. (For us here in the US it's 208V between phases and 120V between phase and neutral [208V / √3 = 120V]).

 

[arrie]

Yes that's what it's short for, South Africa.

Come to think of it, even the geysers could be 3-phase, but I'll have to check.
That's right then, three phase in, and from there you pull your single phases.
Every normal appliance(fridge, microwave tv, etc.) is 220V at 50Hz, except the stove and geyser I think.

 

[saturn1bguy]

Come to think of it, even the geysers...

Well, you got me again. Geysers??

 

[Nigel Goodwin]

Well, you got me again. Geysers??

Shower perhaps?, or water heater?.

 

[JimB]

Geyser - a hot water heater.

Named after the village in Iceland where there are "geysers"

JimB

 

[arrie]

Sorry I did not even think of that.
You don't call them geysers, shucks (oops, another south african term), I thought that is like an iso standard term.
But yes, it's like a beeeeeg (rather big) kettle like thing, we install them in the roofs (between ceiling and outer roof tiles or whatever) of our houses to heat the water. If they burst the whole house floods with hot water, I know, great idea isn't it.
You just call them water heaters? Geysers sound better, I'll stick with that.
This is so funny.

Another interesting thing is that South Africans are slowly converting to a pre-paid electrical system. there is good logic for this, using the normal account system whereby the local municipality sends you an account for usage at the end of the month meant you would pay around R600 or more per month for electricity use, switching to the pre-paid system means you can get through a month just using around R350 for electricity.
Is that not amazing. No one can explain it, well I can, but I'm not making a big fuss about it.