What are ground loops?

[sherry canon]

Hey, guys, I just recently bought a cctv from a home monitoring alarm company I had it all installed but when I checked the video feed it had gray lines all over it. I don't know what could go wrong with it. I bought this cctv for my home. The technician said that it could be a problem of ground loops. All these technical terminologies are confusing to me. If anybody could break it down and explain it to me in layman's terms, it would be great.

[MartyinSC]

Generally, it's a loose term for poor grounds, where sometimes some voltage that should terminate at one device "floats" along a poor ground to another branch, where it finally finds a route to ground. That's the theory. I guess he's saying that poor grounds in the house, not his wiring, are causing those lines. It could just as well be his wiring, or by installing things too close to motors, microwaves, and things that cause emissions. You could get a real electrician to check out your house, and if he gives it a clean bill of health, then go after the cctv installer. But be warned, you're looking right into a can of worms!