Help.....question about ammeters.

Ammeters must be used in SERIES with the current. What you propose would essentially connect 2 ammeters across 240 volts, or each ammeter across 120 volts.

DO NOT CONNECT AN AMMETER ACROSS the AC LINE!! It could literally explode and cause a fire.

It would be *much* safer to use clamp-on AC ammeter probes. Please consider buying, borrowing, or renting a couple of "amp-clamps", before you try measuring the AC currents with in-line meters.

If you absolutely must measure the AC currents directly, break each of the hot lines and connect each ammeter separately, in series with the break in the lines. for strictly 240 volt loads, the current should be the same in each hot line. If there are some 120 volt loads inside the device you are measuring, then you will see a difference in the 2 ammeter readings.

Thanks for the reply! But if connect the ac ammeter probes in series and connect it to the single meter, the reading is always less than; connecting them separately and adding the two seperate readings. Why?

In the case of a balanced load (identical currents in the hot wires), there will be no current in the neutral ... otherwise the difference between the two will flow in the neutral. I don't know if that will help clear things up but thought that I'd point it out.

In many 240 volt appliances, there are separate loads within. For example: in an electric dryer, the heater is a 240 volt heating element, so all current in one hot side will be the same as the other

-- but the motor is generally a 120 volt motor and the motor current flows from one hot side to the neutral (and not "out" the other hot side). Other smaller loads (timer, any electronics modules) are also generally 120 volt loads, also. That's why the current measurements would be different for each hot side of the 240 volt line.

hope this helps, Tom

Thanks all....I now think I have a better idea of how to monitor the current load. I will use a three-way toggle switch and monitor each ammeter coil one at a time. Once I've noted the readings of each coil, I'll sum them and the total should be equal the total current load?

Thanks!

what's an ammetter coil?

if they don't make electrical contact with the live conductors that they measure the current in you could possibly connect them both to the meter at the same time and get a useful reading...