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DMM LEads and Resistance

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DW1961:
If touch the leads together on continuity and they read .002-.005 does that mean the leads are introducing resistance? When I replace them with others, I get 000 all the time. SO I know it must be the leads.

MosherIV:
All wires and connectors introduce resistance. It may be very small (milli ohms).

Some DMM deliberatly show 0\$\Omega\$ when less than a certain value, to fool you into thinking the leads are 0\$\Omega\$

Decent DMMs show exactly what they are measuring.
Most of my DMMs show between 0.01\$\Omega\$ and 0.06\$\Omega\$ which is normal.
(fyi I have 15 DMM so I should know)

coromonadalix:
On some meters you can remove any introduced leads impedance / resistance with the REL  function, but there is a limit to the value who can be nulled, depend on the meter brand and capability

DW1961:
Thanks guys. Much appreciated.

graybeard:
It is a combination of the lead resistance and the contact resistance.  There is a contact resistance between the banana plugs and sockets on the meter as well as the point where you are toughing the leads together.  There is also contact resistance between the leads and what ever you are trying to measure.

The contact resistance increases with surface oxidation.  Sometimes just a few mono layers can screw up low resistance measurements even though the surface looks good to your eyes.

That is why for low resistance measurements is is best to use a Kelvin or 4-point method.   The force leads force a fixed current and the sense leads read the voltage.  Since the voltage leads draw no current the is no effect from thier contact resistance.  However there can (and usually is) some voltage offset due the contact potential.  So long as the current force leads can overcome whatever series resistance there is between them, this method is very reliable for low value ohms measurements.

If I want accurate measurements below a few tens of Ohms I use a Kevin measurement when possible. 

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