All you need to do is download the spreadsheet and enter a few bits of info. How it works To calculate your cost per month you will need a copy of your last few power bills, and this spread sheet. If you just want to estimate and know how your power billing works just check out the pic. First you need to find out how much your power company charges you and how much you allready use. Take your power bills out to do this. There are three things you will need Total Usage, a Baseline power allotment (this is important as you go over this Base the price per kWh will increase), and the Pricing. Next find your setup, or enter your own on the Lights sheet. Lastly enter your info. Start with info from your bills. Previous Usage cells, enter your Total Usage from your last 3 bills. Baseline, find and fill in you baseline power allotment. Pricing, Dont worry if all the entrys arn't on your bill, they usualy increase by $0.05, just fill them ALL in. Your Lights,enter the number you looked up on the Lights sheet. On to Version 2. Let me start by adding this post By using the new Ohm's Law section you will be able to get even more exact with your estimate. I recomend useing this section to get your actual watt usage. As pointed out by babygro and A Good Keen Man useing only bulb comsumption and not power loss in the ballast will throw your results by up to 15%. By useing Ohms Law i think it will be more around 5% Give or Take so I added a range of costs derived from -5% to +5% less or more KWh usage. 98% of electronic equipment will have its Amps posted on it somewhere. As for your voltage just about everyone should know their local voltage but it is usualy posted to. Refferances: GCSE Physics: kilowatt-hour <---How to do the math yourself. Electric Bill Detail - PG&E Bill <---Sample Bill. download: Download Central <---Free Open Office Well I hope this is informative and helps you find your right setup for your homes Power Base. To unlock document toke.

i looked it up, man! i need to switch electric company for 30 days 16h per day it will cost me £80.00 i think , if i have done it right. I havent got an electricity bill as it is a prepaid meter when the cash runs out it goes off. but i do know its more than double what i normally use.

Hey 420 guy... Your post is a fantastic contribution to the site. It will eventually be moved into the FAQ section..... cheers GK

Thought all of you might also find this Kill A Watt meter interesting! http://www.bghydro.com/BGH/Itemdesc.asp?ic=MKAW&eq=&Tp=

Yes I do, but it's kind of worthless for me though. I was curiuos about it and bought one. Works great, and comes with the formula for figuring out consumption and cost. I use solar and wind power to offset the cost of my electricity bill.

Thanks! A friend turned me on to it when he sold his house, and this is mostly what powers my grow rooms. Which is a good thing because anytime we have electrical storms here in Colorado the power boxes seem to always get hit by lightning. Guess they are not grounded very well (lol). Can't even begin to count how many times the power has went out and the solar and wind power have saved my plants.

great thread, thanks guys, some real good info! hey Vote, bghydro is pretty damn good site! cheers fellas

Hi there ya all. Just a quickie thought, appears that your calcs takes into consideration the burner (bulb or tube) only, there are losses with the control gear as well, abt 5%. (that is the heat you feel coming off the box) I'm talking about a HPS setup, though same is true of fluros too, though to a lesser extent. Generally, there are higher losses in older control gear (more total watts) and less light from old burners. (things don't grow as well or happen as fast.) Cheers . .

Yes I just did the bulb sizes to keep it simpe for everyone. But the math is solid. All you would need to do is add 5% to Your Lights total for a little leway. You could also use the Your Setup cells to get totals for your pumps, fans, or anything else that has a steady draw and is on a timed schedual. Add them to Your Lights totals and get a Compleat cost instaid of just lights. Anyways thanks for your input and I hope it was informitive.

Ohms law is relatively straight forward and can be used to calculate an accurate figure of wattage useage from any light system, and this would probably have been a better way to go. To calculate total wattage used from a ballast HID system you need to use the amperage figure not the bulb wattage figure. To show you how your figures are inacurate, OHMS Law is Volts x Amperes = Watts, so if we know two of those figures we can calculate the third. The real wattage of a 400w HID system is Volts x Amperes or 120 x 3.8 = 456watts for an average 400w system others would be - 250w 120 x 2.5 = 300w 400w 120 x 3.8 = 456w 600w 120 x 5.7 = 684w 1000w 120 x 9.5 = 1140

Sorry, didnt really mean for the subject to become pedantic, only to point out that there is greater amount of current used than that stated on a burner envelope. However, for the record. I have a small (this one is abt 6 long ) clamp amp meter that I use on occasion. (any clamp ammeter will do, it dont have to be small) Place around either the active or neutral wire that supplies power to your growery, turn on all lights, pumps, blowers scrubbers etc., read off current. Current X Volts = Watts divided by 1000 = Kilowatts X 1Hour = 1 Kilowatt hour The Kilowatt Hour is the unit the utility company charges you for, I pay abt NZ$0.16 per kWh. Will try and include photo of meter if this forum allows. (and I can find out how) Keep on growing everyone, weve just got to win this war . . . More is better, much more is much better, most is best. (I know, cause I paid for it.)