This whole area can be really confusing. There is sort of a residential look the other way code situation where multpile standard 15 amp outlets can all be connected to a single 20 amp
breaker. Thinking is that in a home you rarely use the full 20 amps on a single connection, so the flexibility and probably infact a cost savings. The the wiring from the
breaker to the outlets should be 12
awg wire. One other problem with the tester is it only really works if you can find every
outlet on the connection. Sure it will tell you if the
outlet is connected to the
breaker, and that is great information, but usually what gets you is the odd ball extended
outlet somewhere that is also on the branch, the device plugged into it is turned off at the moment, and the receptcal is off in some really weird place. You get all set up think you are good to go and find out that some coffee pot or hair dryer or exhaust fan or something is on the same branch.
this is why in pro setups you just about always try to get your own
distro, get it connected into the panel, and then you know exactly what is on the
system from the panel to you. I have found that bringing along a Square d
breaker and a Siemens
breaker also helps, since you usually can get a local electrician to do the interconnect, if you have your own
breaker then you don't need to have a
disconnect etc.
While
ohms law works in many cases, typically with a lamp on a
dimmer it does not quite work the same way, so, if the
voltage is lower, it is not like the
dimmer/lamp draws more amps, in fact I think you will find that in a ac
system, what you get is a lamp that does not go to full brightness, so the amps draw will remain the same, it is not like the
dimmer will attempt to draw more amps in an effort to reach the same wattage. It is the difference between resistive vs inductive/reactive load. This for example is why most dimmers do not want you to run inductive/reactive loads and why transformers on dimmers are not a good idea. You do not want the device in an attempt to produce an output to keep increasing the amps to make up for the reduced volts.
http://www.ibiblio.org/obp/electricCircuits/AC/AC_11.html
Anyway just some thoughts
Sharyn