installing security cameras
Monthly Costs

You can evaluate the electricity cost for a security camera setup yourself. Take a look at the cameras that you are interested in and note how much power each camera consumes. This may be a direct rating of Watts or it could specify operating voltage and current. You can compute the Watts from the voltage times the current. So say that the cameras are rated at 12VDC and the current for each camera is 0.25A (equivalent to 250mA). So 12V x 0.25A = 3Watts per camera.

Next you have to consider a power supply unit that would provide the 12VDC for the cameras from mains power. These units are not 100% efficient and consume some power as well. Typical efficiency may be say 75%. So if you happened to deploy 10 cameras at 3W each that would be a total of 30W load on this power supply. The 75% efficiency would mean that the supply will require 30W / 0.75 = 40W from the mains power line.

Electricity is typically sold in units of KWatt-Hours (i.e. 1000W usage for 1 hour). Electricity cost will vary a lot from region to region so for sake of discussion lets make an estimate of 0.25USD per each KWatt-Hour used. (This will be high for some many regions in the USA but for sake of discussion let us guess high). 

Let us base cost of operating cameras on a 30day month. At 24 hours per day that totals out to 24 x 30 = 720 hours per month. The 40W that we computed for the AC line power is same as 0.040KWatt. The total cost of operating cameras day and night for the month will be 0.04 x 720 x 0.25 = 7.20USD per month.

You can follow this process to come to a more realistic calculation based upon your actual electricity cost, the number of cameras you deploy, number of hours of operation per day and the actual Watts of power used by each camera. The numbers I chose above are just seat of the pants values chosen to illustrate the calculation. Your actual monthly cost may be quite a bit lower or could be higher if you chose to use many many power hungry cameras.  

Installation

There are many schemes used to install security cameras. Whether any particular scheme requires you to make holes in your house will depend entirely of things that only you can determine such as:


Type of cameras that you choose to purchase
Method of powering the cameras (battery, DC power wiring or Powered through signalling cable)
How signals get from camera to monitoring system (Ethernet, WiFi, coax video)
Your concerns for camera and wiring hiding versus visibility
Your capabilities and tool resources to try to do a DIY install