How to use a Multimeter around the house?

rysoxDecember 18, 2007

I got a good deal on a craftsman multimeter, but I dont know how to use it besides checking voltage on a battery and using the continuity test. (Dont laugh please). Im leary to hook it up to house voltage till I get a better understanding.

Can anyone suggest a good text online that would describe exactly how to use my new multimeter in regards to house wiring.... checking for voltage at outlets, fixtures, voltage drop etc. checking to see if switch is bad etc? The manual doesnt go into those specifics.


Thank you for reporting this comment. Undo

There's some good information on the Fluke site, even if you have a different brand of meter. Look for the "Diagnosing Power Problems at the Receptacle" and "Stray Voltage" application notes. You should also look at their Safety section.

If you search YouTube using the phrase "multimeter explosion" you'll find a couple of videos showing what can happen if an el cheapo meter is hooked up wrong.

Here is a link that might be useful: Fluke Application Notes

    Bookmark   December 18, 2007 at 11:36PM
Thank you for reporting this comment. Undo

NEVER try to measure continuity or resistance on a LIVE circuit.
Some meters have fuses, but the electronics almost always goes before the fuse.

You also need to understand the difference between analog meters and digital meters when even measuring voltage.

    Bookmark   December 19, 2007 at 8:43AM
Thank you for reporting this comment. Undo

I hate blue sparks, so I want to make sure I dont trip a breaker or burn my fingers off before probing around.

I assume polarity doesnt matter with AC? So it doesnt matter what color probe I use to test switches and outlets. But it is important when testing stuff on my vehicle becuase that runs on a battery.

And to test hot to neutral or hot to ground... I can just insert the probes in an outlet?

And if I were to test hot and ground with the cover off... I would use the electric box as the ground (no ground wires in my box)?

    Bookmark   December 19, 2007 at 12:26PM
Thank you for reporting this comment. Undo

read the book that came with it, it will give you the basics.

remember, if you set the meter for ohms or amps, BE SURE YOU RESET TO VOLTAGE. i cannot tell you how many times i have set a meter to ohms then tried to measure voltage a few minutes later and popped the fuse. i finally got in the habit of omhing, remove the leads, then turn the diaal before i do anything else. and in amp mode you create a dead short so that is NOT good.

yes, you jsut stick the probes in the outlet. if you have the cover off, touch them to the screws of the outlet or stick them in the front, either one works. i prefer to touch the screw terminals just on the off chance the outlet itself is bad.

as far as workign on your car, if you are checking voltage or current, the meter will still read with the lead reversed--it just will read it as negative. you do NOT go positive to negative when reading DC current, you break the positive line. for AC current, READ THE MANUAL as every meter is different. some do not even do AC current, where some require a seperate clamp to read it.

    Bookmark   December 19, 2007 at 1:09PM
Thank you for reporting this comment. Undo

rysox...if you are doing some testing on your vehicle, I hope your meter is digital. Do NOT use an analog meter for testing on computer controlled vehicles. They can damage delicate computer circuits.

    Bookmark   December 20, 2007 at 8:02AM
Thank you for reporting this comment. Undo

"And if I were to test hot and ground with the cover off... I would use the electric box as the ground (no ground wires in my box)?"

No ground wires = no ground. Period.

    Bookmark   December 20, 2007 at 8:24AM
Thank you for reporting this comment. Undo

If the entire system uses metal conduit, isnt that considered the ground? Im assuming this is a common setup in chicagoland since I think metal conduit is required by code.

Sorry if im wrong, I dont even understand how to use my multimeter correctly.... yet!!! :^)

One question, with the grounding system as described, if someone buys a new fixture, say a ceiling light, that has a ground wire... do you just snip the ground off the fixture or cap it and stuff it into the box or is it supposed to connect to the electric box? Or do light fixtures even have a ground wire??

    Bookmark   December 20, 2007 at 12:20PM
Thank you for reporting this comment. Undo

Sorry, I didn't catch the part about conduit. Metal conduit is an acceptable ground.

    Bookmark   December 20, 2007 at 10:21PM
Thank you for reporting this comment. Undo

I didnt clarify that before. However, what about the ground wire that may be attached to a fixture.

Clip it, cap it or connect it the box with one of those ground wires with the screw attached to it?

    Bookmark   December 20, 2007 at 10:58PM
Thank you for reporting this comment. Undo

Connect it.

    Bookmark   December 20, 2007 at 11:51PM
Sign Up to comment
More Discussions
Well this sucks
Just when you thought the idiot popup ads in the gardenweb...
Ron Natalie
Looking for Ideas For Lighting at base of 300' long driveway
Sorry for the "picture through the screen"...
Ceiling fan wiring
I have a new ceiling fan with a light. The fan has...
Replacing dimmer switch: different wire colors on new switch
My DR lights, which are controlled from two switches,...
Light boxes on/in 6X8 timber floor joists for log home
Just trying to figure how to wire a couple light fixtures/chandelier...
© 2015 Houzz Inc. Houzz® The new way to design your home™