Multimeter

[dsesmg]

Hi, how are you?
I have a basic question for multimeter.
Today, I was playing with my multimeter and I measured continuity.
When I put red and black handle(?) on the same conductive object, the multimeter creates sound and it shows 000 on the LCD.
When I put red and black handle on the non conductive object, the meter creates no sound and it shows 1 on the LCD.
But, sometimes the meter creates beaping sound very shortly as soon as I put red and black handle on the non conductive object and shows 109~114 readings on the LCD.
Could you please tell me what this means? Is this mean that the object is conductive?

[Joker94]

it might be the that it is showing the resistance of the objects

[SmAsH]

what non-conductive object is it? some conductivity may be getting through the probes making them
jump from not conductive to conductive.

[wil.hamilton]

some objects will slightly conduct, but, just aren't very good at it.  i could be mistaken, but i think even rubber can conduct electricity, its just not very good at it

[dsesmg]

Hi, the object i was referering is an aluminium and two steel bars are attached to it.
I measured those two steel bars by the multimeter. To my understanding, aluminium is not conductive.
So, if I put both side probes on the steel bar, the meter shouldn't make sound but it sounds a short beap and shows 19~114 reading.
I am going to put some strip of copper plate(0.3mm thick) on each steel bar and supply 9v on them.
But, isn't it short circuited if this reading is indicating that it is conducting electricity?

[spizzak]

Why wouldn't aluminum be conductive?

Aluminum, steel and copper are all good conductors

[dsesmg]

But, if I put two probes in the aluminium, the meter shows it is non conductive.. so.....

[spizzak]

It might be coated with something, try scratching it a bit with the probe or some other sharp object and then measuring, also if it's a really large piece the multimeters voltage might not be enough. Try putting the probes closer together as well as seeing if there is any coating on the aluminum (ie. anodized) and scratching that off.

[dsesmg]

Hi. Yes, I can try that. But, the aluminium structure I have is kind of big and connected with many things.
The two steel bars are already mounted on the aluminium structure and it is difficult to layout some rubber sheet or something.
I would like to ask whether it is ok to supply 9V to those steel bars that are attached to the aluminium structure even though I get conduction readings from the meter when I probe it. Can I ignor 109~114 readings and go on with power supply?

[spizzak]

I really don't understand what you have there, or why you want to supply 9v to some steel bars... but from what I gather, the steel bars are somehow connected with a sheet of aluminum, and in that case you will get a short. But when you're talking about steel bars and sheets of aluminum it sounds like this structure is massive, so it might even be enough for the current from the 9v to just dissipate. Either way, it sounds like a bad idea to me, but like I said its kind of hard to understand what your trying to do.

[wil.hamilton]

aluminum oxidizes really fast, this oxidation may block conductivity, aluminum is an ok conductor

[madchimp]

well considering aluminum is sometimes used for wires I would say it's a conductor and a pretty good one at that. The reason your meter isn't reading it as such is probably due to a coating as many people have pointed out already.

[dsesmg]

Thanks you very much. That's very helpful.
Yes, I searched for more information and the aluminium material I have is aluminium profile.
It has been anodized.