please give the wattage on the cameras and the hours of usage per day please (I guess 24 hours), oh and how much you pay per kWh of Electricity.
We are a PFI school and recently had our CCTV upgraded. Duribng the install wer had 7 new AXIS IP cameras installed, running back to three Netgear POE switches.
The PFI company reckon that it will cost an additional £800 in electricity for these cameras.
Now I have the task of trying to work out how much they will really cost to run.
Not being an electrician or mathematical of mind I have no idea how to work this out.
i have the Watts that the cameras use and the maximum for the switches but I don't know how to relate this to cost?
Anyone out there have any ideas how to do this?
Thanks
please give the wattage on the cameras and the hours of usage per day please (I guess 24 hours), oh and how much you pay per kWh of Electricity.
My rough costs:
Assuming each camera uses 10W (5v 2A) which is plausible, 3 cameras 30W
Cost per kWh used from EDF - £0.1352
365 days in a year
= £35.53 per year
Think that's about right. Your cost per unit may be much higher, but not £764.47 higher.
reggiep (19th June 2014)
Axis M32 series camera Power over Ethernet IEEE 802.3af Class 2 (max. 4.2 W) seven of them
three Poe switches that have a maximum power of 256 watts that have a netear green sticker on them, for what it's worth!
Can sopmebody show me the formula that you use for this, for my future development!!
I must admit, £800 does seem rather high. I'd agree the above calculation is a lot more realistic. With 7 cameras it'll be close to the £100 mark, but then again, you could argue this is already accounted for as you're most likely using a PoE switch.
1. Watts = 4.2W
2. Watts/1000 = kilowatts or kW = 0.0042kW
3. Hours used in month (use an average) = 730.5 Hours ((24 hours in a day * 365.25 days in a year) / 12 months)
4. Kilowatts x Hours = Kilowatt Hours or kWh 3.06 kWh
5. Electricity price (in pence per kWh - enter the cost you pay) = 0.1352 pence (Based on the above EDF costs)
6. kWh x pence = Cost (in pence) to run the item for 1 month = 0.41 pence
7. Number of the same items in the property = 7 Items
8. Cost to run all such items in property for 1 month = £0.029p
9. Total cost per year for all 7 cameras = £0.203p
I ran the calculations 3 times, and they check out. Just adjust the wattage and unit cost and you have a sound figure for working out how much something will cost in energy pricing etc.
Last edited by nephilim; 19th June 2014 at 12:26 PM. Reason: fixed for your wattage, just need the unit price for accurate figure
reggiep (19th June 2014)
Very simplified:
Find the energy used by each camera in Watts (I made a guess based on a typical AC-DC PSU, but with PoE you're looking at 48V and x A. Energy (W) = volts x amps. The efficiency of the power supply is not accounted. Now convert the energy in Watts to kW (/1000).
24 hours in a day. Multiply your figure in kW by 24.
365 1/4 days in a year. Multiply your daily figure by 365 1/4.
Multiply the final total by the cost per kWh in £.
????
Profit!
reggiep (19th June 2014)
I get it as £51.51 for all seven cameras!!
Watts /1000 x hours x cost per pence
4.2 / 1000 x 8760 x 20p = £7.36 x 7 = £51.51
I'd ask how they get to the £800 figure as your figures above are more realistic.
Do you already have PoE switches in place for your WiFi? If so how much do they charge you for the privilege of running them!
Are you sure they said just electricity costs?
PFI does full life cycle cost recovery across the length of the contract.. So they might be taking into account a refresh of the services provided into those costs (and they take into account things and time costs more in the future).
Bloominel, I can run my house for a year for less than that!
two 1080p CCTV cameras and a HP Microserver as the DVR
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