Electrical bill

[VanTheMan]

Ok, so the city I just moved to (Niles, MI) has a utilities website that outlines rates. In the electric rates, it says they charge $11.48 per kVA and allow 200 kWH per kVA billed.

I'm wondering how I can calculate how much it would cost to run my computer (420 watt PSU) or my space heater (1300 watt) for an hour or something. If anybody can explain to me how to do this, I would appreciate it. I pretty much just want to get a general idea of what my electric bill is going to be.

 

[dartworth]

http://www.p3international.com/products/special/P4400/P4400-CE.html

 

[KLin]

http://tristate.apogee.net/lite/lecoeuc.asp

So using a 420 watt psu at 100% load for an hour/day would be (420*1)/1000=.42 kwh used per day. 10 hours = 4.2 hwh per day.

 

[VanTheMan]

My utility company charges by the kVA, though. They allow 200 kWH per kVA billed. I found a formula to find kVA: kW * power factor. It also says that power factor is the only difference between kVA and kWH.

So, assuming the power factor is 80%, if my 420W PSU draws 3.5 amps, then the kVA is .525. My space heater would be 1.65. They charge $11.48 per kVA, but what time measurement is used? I guess I just don't understand how the kWH allowed per kVA are used. I can't convert from kWH to kVA using power factor because kWH is a measurement of energy used over time, but kVA is not.

When I turn my computer on, it draws .525 kVA and .42 kW. How can I figure out how much it costs to run my computer for an hour? They don't charge a price per kWH unless I exceed 200 kWH per kVA billed.

 

[VanTheMan]

I was just reading some more and I saw that kVA is billed by demand. So, if I'm billed $11.48 per kVA does that mean they rate my peak demand each month or something and then allocate 200 kWH to me for each kVA?

 

[I Saw OJ]

Dude, you're looking way too hard into this. Are you on that much of a budget that you need to figure out the exact amount your electronics are costing you per hour?

 

[neutralizer]

Originally posted by: I Saw OJ
Dude, you're looking way too hard into this. Are you on that much of a budget that you need to figure out the exact amount your electronics are costing you per hour?

Agreed. Why not just conserve energy as much as you can i.e. hibernate, suspend, whatever?

 

[VanTheMan]

I'm just curious and I was hoping there would be somebody on here who would know enough about it to explain it. I don't think there's anything wrong with trying to acquire knowledge while I'm bored at work. I'm not on that much of a budget, but I do have housemates who like to run their space heaters and computers a lot so I'm trying to get an idea of how much things are going to cost so we won't be surprised with a huge power bill.

 

[mobobuff]

Originally posted by: VanTheMan
I'm just curious and I was hoping there would be somebody on here who would know enough about it to explain it. I don't think there's anything wrong with trying to acquire knowledge while I'm bored at work. I'm not on that much of a budget, but I do have housemates who like to run their space heaters and computers a lot so I'm trying to get an idea of how much things are going to cost so we won't be surprised with a huge power bill.

The space heaters should be your primary concern. In terms of sheer watt consumption, space heater > computer any day. A space heater will draw a consistent amount of juice, whereas your computer will draw more or less depending on what you're doing.

 

[I Saw OJ]

Originally posted by: VanTheMan
I'm just curious and I was hoping there would be somebody on here who would know enough about it to explain it. I don't think there's anything wrong with trying to acquire knowledge while I'm bored at work. I'm not on that much of a budget, but I do have housemates who like to run their space heaters and computers a lot so I'm trying to get an idea of how much things are going to cost so we won't be surprised with a huge power bill.

Bored at work? Well then continue on your quest! I'm at work too.

Your computer isn?t going to draw that much power, I have two computers running all the time and my power bill is ultra low. However those space heaters your mates are using draw a lot of power and will be noticeable on the bill.

When I lived with my 2 roommates, we used the regular heater during the winter however one mated needed his room sweltering hot so he got a space heater. There was a noticeable difference on the power bill, so we had him pay a little bit extra to use the heater since he ran it 24/7

 

[rockyct]

Originally posted by: VanTheMan
I'm just curious and I was hoping there would be somebody on here who would know enough about it to explain it. I don't think there's anything wrong with trying to acquire knowledge while I'm bored at work. I'm not on that much of a budget, but I do have housemates who like to run their space heaters and computers a lot so I'm trying to get an idea of how much things are going to cost so we won't be surprised with a huge power bill.

Get the kill-o-watt thing. Saying you have a 420 W power supply really doesn't tell us much. When wattage numbers become a "feature" and not a real rating, you really have to take them with a grain of salt.

 

[0roo0roo]

well to save power unplug unecessary electronics, esp those with those big chunky wall wart ac adapters, those just use power even when off. newer more efficient versions are smaller and much lighter. use a power strip.

buy a 20 dollar kill-a-watt meter or equiv to measure use. 420watt doesn't mean much as said, and it also depends on efficiency. cheap cr@p psu with low efficiency will pull a lot more out of the wall than it delivers, and they are rated for delivered watts, not used.

 

[josh0099]

Originally posted by: VanTheMan
Ok, so the city I just moved to (Niles, MI) has a utilities website that outlines rates. In the electric rates, it says they charge $11.48 per kVA and allow 200 kWH per kVA billed.

I'm wondering how I can calculate how much it would cost to run my computer (420 watt PSU) or my space heater (1300 watt) for an hour or something. If anybody can explain to me how to do this, I would appreciate it. I pretty much just want to get a general idea of what my electric bill is going to be.

Pretty sure that website quotes are only for industrial clients...Most residential customers are just charged by kWH. Only reason your power factor should be even close to .8 is if you are running some big time motors or something which a normal house hold would not run.

 

[Kelemvor]

Definitely get a Kill A Watt for this sort of thing. They are great and lots of fun to play with.

 

[mrrman]

Originally posted by: VanTheMan
I'm just curious and I was hoping there would be somebody on here who would know enough about it to explain it. I don't think there's anything wrong with trying to acquire knowledge while I'm bored at work. I'm not on that much of a budget, but I do have housemates who like to run their space heaters and computers a lot so I'm trying to get an idea of how much things are going to cost so we won't be surprised with a huge power bill.

If not already done so I would change out all the regular bulbs to CF lights,,there will be a huge savings there...the rest of the stuff is neglible

 

[Matthias99]

Originally posted by: josh0099

Originally posted by: VanTheMan
Ok, so the city I just moved to (Niles, MI) has a utilities website that outlines rates. In the electric rates, it says they charge $11.48 per kVA and allow 200 kWH per kVA billed.

I'm wondering how I can calculate how much it would cost to run my computer (420 watt PSU) or my space heater (1300 watt) for an hour or something. If anybody can explain to me how to do this, I would appreciate it. I pretty much just want to get a general idea of what my electric bill is going to be.

Pretty sure that website quotes are only for industrial clients...Most residential customers are just charged by kWH. Only reason your power factor should be even close to .8 is if you are running some big time motors or something which a normal house hold would not run.

Agreed. I've never seen a residential customer in the US charged by kVA, although there may be some out there. That website does make it sound like you'll be charged that way. It's very common in other countries, just not the US. Most big things (electric stoves, electric heat, etc.) you're going to run in your house have a power factor close to 1, so unless you're running a whole computing cluster I doubt it would impact your bill much anyway. A power meter (like the Kill-A-Watt one mentioned several times) should tell you the wattage and power factor of anything attached (not sure if it will calculate in VA, but you can convert).

With a power factor of 1.0, 120VA would be equal to 120WH (a 120W load for one hour will pull 1A@120V for one hour; 1A * 120V = 120VA). With a power factor of 0.8, that 120W load for one hour would actually pull 1.25A of current (1.0A / 0.8 = 1.25A), and so your 'real' load on the grid would be 150VA (1.25A * 120V = 150VA).