how do I read a digital multitester to find hotwire. Two leads black and red.?

Answer 1

Several answers, none are totally correct because there are too many things that you did not specify in your question.

First, what kind of circuit are you measuring? It does make a difference in the answer, absolutly.

If it is a vehicle, it uses dc. Turn the switch on the meter to dc volts. If there is a voltage switch, set it to something more than the expected voltage. Typically 12 volts in a car actually measures around 13+ volts. Black test lead to the chasis, red test lead to the wire you are testing.

In vehicles, the black wire on the vehicle is typically ground, i.e. negative. The hot wire, i.e. positive, can be any color. It depends on the individual circuit.

If it is a house or other building, set it to ac. Voltage is typically 115 or 230 volt nominally. Most meters with a voltage switch have a 300 volt setting that is good for this.

Black test lead to ground (bare or green) or neutral (white) wire. Red test lead to check for a hot wire. Black wires are the most common hot wires. Red is used for some purposes.

Sometimes, you will find a white that is hot in a switch circuit. That makes things a bit confusing.

There is NO polarity in ac, just a hot and a ground. Technically, there really is polarity, but thinking about it is way too confusing for an untrained person to understand and the difference is too technical for most people to need to know.

Answer 2

WAIT! Don't put it on ~ (ohms) with the power on the wires. If you are working on a switch with two lead wires, black and red, it is probably a 3-way switch. If you are talking about the leads on the meter. Turn the dial to a/c, place the black lead to ground (bare wire) place the red lead to each of the other wires. If you have 2 or 3 wires where you are looking for power. Usually, white is neutral, and black is hot.

Answer 3

turn it to ~ then touch the black end to some type of metal ground and the red end to the wires to get a reading. The red should be your hot, one black ground and one negative.