Simply "clamp-on" the clamp of the amp meter to any electrical conductor supplying the equipment that you wish to check while it is in operation. It is better to use your clamp-on with each individual conductor one at a time.
Yes, when using a step down transformer the amperage is affected.
An ammeter measures amperage not voltage.
they would get soil reading from the short one, obviously, and body readings from the long one.
Wire size is based on the amperage drawn. To find the amperage, the voltage must be stated. Use this formula to find the amperage. I = W/E. Amps = Watts/ Volts. Once you have the amperage, restate your question using the new found amperage or state the voltage that supplies the lights.
Larger wires will not reduce the amperage draw of a device. Limiting amperage draw is accomplished by fuses wich blow when the amperage drawn across them exceeds their specifications.
The easiest method today is by using a clamp meter. It "clamps" around a single conductor and measures the magnetic field (you can't get a reading by clamping around a regular appliance cord, as both conductors will cancel each other out).
Your meter might be jumping because you are using a lot of electricity. This could be because you are washing or drying clothes, or even using the air conditioning system. Also, using computers a lot uses a lot of electricity, which may cause the amperage on the meter to jump.
The use of a breaker in a circuit is to protect the wire size used in the circuit from becoming overloaded. Using the wattage of the load does not help for breaker sizing because the breaker operates on amperage. Amperage can be found from wattage by using the following equation. I = W /E. Amps = Watts / Volts. As you can see the amperage can not be calculated because there is no voltage stated.
To obtain amperage from a formula you need at least two components. Formula for amperage are I = W/E, I = E/R and I = sq root of W/R.
Wire size needed depends on amperage, not watts. If you know the voltage of the power supplied you can calculate the amperage using this form of the "power formula":A = W / VThen there are tables that tell the amperage each wire gauge is capable of carrying. Just select the gauge that has the amperage rating just larger than you calculated.