OHMS for a really DUMMY

[Bow42]

When it comes to measuring ohms with an meter I totally lost.
So in plain English and as simply but details ,
If I wanted to know what is the resistance in a length of wire or how much volts are lost,
how would I go about it .
were do i start.
My meter as setting of 200,2k,20k,200k,2m,20m,200m, what setting do I use? .
What reading would I expect to see ?
What a good reading and what’s a bad one ?
As I said I am a really dummy when it comes to this but I like to learn.
Please help .

 

[jwilson]

Use the 200 ohm setting, but a normal cheap multimeter will be very unlikely to read low enough to measure wire resistance which will probably be a fraction of an ohm unless you are measuring a very long wire or a badly corroded one.

 

[bedouin]

Very hard to measure the resistance of a wire using a meter and the numbers are so small.

If you are interested in voltage drop it is usually calculated rather than measured.

 

[Poignard]

There are tables online that will give you the information you need

 

[Bow42]

Very hard to measure the resistance of a wire using a meter and the numbers are so small.

If you are interested in voltage drop it is usually calculated rather than measured.

so lets say i had wired up a panel and I want to find out if the wires I had used are big enough ,if there a voltages lost .

 

[pmagowan]

Here is a conductor size table for 3% voltage drop: https://marincofaq.files.wordpress.com/2012/06/tableb3at121.jpg

 

[JohnGC]

so lets say i had wired up a panel and I want to find out if the wires I had used are big enough ,if there a voltages lost .

Turn the circuit(s) on and measure the volt drop.

 

[bedouin]

so lets say i had wired up a panel and I want to find out if the wires I had used are big enough ,if there a voltages lost .

a) you can calculate it fairly easily by working out the current draw (from the specs of the devices) and the size of the wire, but for short runs it is rarely an issue. For short distances (a few feet) if you stay well within the current rating of the wire the voltage drop should be pretty small. There are standard tables out there that can help with that.

b) If it is an existing installation you can actually measure the voltage drop in situ by connecting the meter between the battery terminal and the live terminal on the device. (And again for the negative)

 

[johnalison]

Turn the circuit(s) on and measure the volt drop.

Surely the easiest way. Just measure the volts at the switch panel which is where I presume the wire starts, and again at the appliance.