If you have a clamp on amp meter and go around two wires of the same circuit they cancel the magnetic field they create when they draw current . . . however if there is a short to earth ground the current flow will be unbalanced and you will read a current. Drywall screws into wires in the wall are the typical problem and critters chewing the wires.
Cool! Thanks for the info. While I didn't know that fact before now, in retrospect (when I think about how a clamp meter works, which FWIW is pretty much the same principal that TED uses to measure house power) it makes a lot of sense!
I do in fact have a hand-held "clamp meter". Before I heard about TED, I got it as a tool to try to track down this power usage problem, but never used it much because of the hassle of isolating one wire from a pair. Until now, I never knew that it has an even more useful (and easy to do) function as a whole circuit test for "power loss to ground"! So when I get some time to play with the wiring (given other family/work commitments, and the fact that I may be starting to get sick, it will probably be this weekend at the earliest before I get back to this), I'll run that test over the various house circuits (the two circuits I noticed the "issues" with will be "at the top of the list" for checking). That should quickly tell me if leaking to ground is a problem (and if so, which circuit(s), and roughly how much current is leaking), or if something else is going on.
The "detective work" is on. But at least now I'm actually starting to see the "real problems", vs just "guessing". Amazing what the proper instruments (along with some idea of what they are good for) can tell you. Imagine how much electric power (and the resulting electric bill) I could have saved, if I had been able to get these tools (and info) a few years back (vs just trying to improve things "blindly", and thereby continuing to pay high electric bills because I was missing "hidden" power usage).
I wonder how surprised the power company will be, if our home starts (consistently) using a fraction (1/2 of less) of the power we have used for years?
Oh well. On "the bright side", one thing that TED did start to show me, is that at least some of the places where I already worked on "energy efficiency" (while far from the worst offenders), do in fact have decent energy efficiency. Take lighting, for example. While the TED is sensitive enough to notice the power difference in even a single "compact florescent" light turning on, the extra power usage difference is small. And even when the family has a lot of lights, TVs (most of the TV are "energy star" rated), etc. turned on, the power usage is still very reasonable in those areas I previously worked on. It was the things I didn't previously think to check for, or was unable to figure out how to check for (power loss to ground on a circuit, the real power usage of the sump pumps, the power of the central air blower, etc) that seem (with the little investigation I've done this week) to be where many of the problems still remain. So if I can get a handle on some of these "big boys", and maybe do a little more with "phantom losses" from the consumer electronics (when they are turned off), I should be in pretty good shape. Because I already have some of the other "basics" (lighting, being a big one) addressed.
Well I had to order one. I also have a good Fluke clamp on meter but only I can use it at the main panel hand hate to leave the cover off. This way I can leave the “TED” sitting some where convenient for my wife to see what’s going on.
We did a similar thing on my dad’s house last spring going through every breaker and found one pulling about 4 amps. It turns out his attic lights; five 100w lights were on and had been on he thinks since just after last Christmas. Ouch! Things like that would be a lot easier to spot with this meter. Maybe I will have to get him one as well
Oh our furnace fan also took about 650w when on in “fan” mode. My wife really likes the circulation and filtration (also connected to a heat recovery ventilator). So I messed with some jumpers and found I could set the speeds for the fan, heating and cooling. Of course they were all set for four, the default. So I set the fan speed to one and the fan now takes about 400w and is much quieter but still filters and circulates the air.
I figured out that my little office fridge uses .7kwh a day (week average) and is the biggest power device that runs in my office (185 watts) but for some reason I end up using an average of 3kwh a day and I still have not figured out where it is going. Laptop 30 watts - LCD 26" HDTV 56 watts - Lights 9 watts CF.
And as was mentioned already even if you have a 225 or 300 amp entrance as long as it is two wire this should work fine. More commonly I have seen dual 200 or 225 amp services rather then a larger single panel. You rarely if ever actually pull 200 amps. I do wander what the max is on the TED, but since it is using a clamp on meter of sorts there still should be an issue with damaging the meter itself.
This has probably already been mentioned here but the watts-up or kill a watt are also both great meters that just plug in to the wall and then you plug any item in to them to see exactly how much power they consume.
Is the four pole 200 amp breaker all connected together, as in one large breaker? Realistically the main 200 amp 240v breaker is really four 100 amp breakers, 2 paralleled for each side of the 240v then all connected to one master on/off breaker handle. This is pretty common (that’s what I have), most likely if that is what you have the TED should work.
The easiest way to tell is to pull the cover and see if you have just two wires coming in. But please if you feel uncomfortable pulling the panel cover get someone who knows about electricity or a licensed electrician to help. If you short the wires on the incoming side of that 200 amp main you short all the way back to the pole, very, very dangerous.