Does a Cable Have Minimum Current Requirement to Conduct

No.

N/A

N/A

Yes.

What is the Electrical standard used in India?

Is it IEC, NEC or IEEE?

It is the Indian Standards published by the Bureau of Indian Standards (BIS), read in conjunction with the Indian Electricity Rules, 1956 and The National Electric Code (of BIS), 2011.

Well, minimum electric charge in nature IS the electron's charge Qe=(-1.6 × 10-19 coulombs) and since cable does have self capacitance (in short, depending on it's dimensions), you do need a minimum voltage for an electron to move in or out of it, and twice as that for both, so to have the smallest possible charge flow or else "current". Also since electric disturbance propagates at (near) the speed of light (C) , the minimum time that the "disturbance" is transformed to "current", because of the above is (almost) solely depended on cable's length. So there is a minimum current: electron's charge*cable's length/C (LOL) S.M.

There is not a minimum current for conduction in the cable. However, depending on the connector and contacts that are part of the circuit one can have oxide build up problems that prevent a small current from being established every time.

Just think of it in terms of a water pipe. If you have a pipe full of water, it's full. If you add one drop of water to one end of the pipe, a drop of water will be forced out the other end. Just don't try to put water into both ends of the pipe at the same as this may cause distress in the piping.

Don't try to put 20mA in both ends of the conductor, either, as that will cause distress in the conductor.

Sorry, folks, but in the context of the OP, we are Not talking band gap, contact resistance or anything fancy except "can I use 0.5mm² cable to carry 20mA?".

I'm getting fed up with the "deep dicussions" which generally start with something more akin to "My Chevvy Won't Start" that to anything very technical.

So, "My Chevvy Won't Start" is OK, but anything more than "Check your fuel gauge" is not? S.M.

Didn't say or imply that. OP axed "will 0.5mm² do the job?". Answer is "yes".

There are obviously many reasons why a Chevvy won't start, but there are very few reasons why a bit of 0.5mm² wire won't be serviceable for conducting 20mA. There is no reason to go further (except technical masterbation).

Nobody liked my hose analogy?

Technical masterwhat..............?

Love it! Will go back and deliver a GA. You've exemplified the lack of depth required for a good answer to the OP's question .

_{(but axing for a GA is sooo infra dig!).}

OH, Thank you sooooooooo much. I have a boundless lack of depth which comes into play here often.

It's nice when someone recognizes that talent when they see it.

OK, while were off topic here and I have a "Problem" or Potential problem and have not been able to resolve it yet. I design and build electro propulsion systems for Elco Motor Yachts.

Been doing this for several years. Now getting into higher voltages and HP's than in the past and running in to Ignition switch issues. Currently I am using a Key switch/Ignition switch rated for 12VDC 15A. Past voltages 12, 24, 36, 48. Now 72, 96, 108, 144. Amps Non inductive loads are 1.5A for 30mS (caught on scope) then .176mA. It's not just this. The contactors I am using are also not rated for more than 96V and yet I have yet to have a failure yet and pushing the 350+ Amp threshold on these contactors. I've been doing electric boats since 2006, my company has been doing electric boats since 1892. Up till 2006 we only went to 8HP @ 48VDC with a DC motor. Now we are doing 3 Phase 24V - 144V AC 3Phase motors up to 100HP and expanding, with DC input of 24-144V. I need an Ignition switch that can handle 150V .126A switching. We are actually writing the ABYC compliance protocols as we are working out the higher voltage/HP issues since ABYC is only up to 48VDC. If any one out there has more experience in this area, I am all ears out. I would appreciate any input in any direction possible. And 12V is not an option, I figured I' dthrow this in as this is already a dead study in the wiring. There is no 12V seperate system to pull from. We have 24, 36, 48, 72, 108 and 144VDC to contend with. HP= 2, 6, 7.5, 10, 20, 35, 100. And working on 250+.

I loved your pipe analogy. I'll vote for a GA on that one. I don't agree that "You've exemplified the lack of depth required for a good answer to the OP's question ." You simply phrased your answer in a way that the OP would understand. It seems that electricity is not their strong suit, so you went with plumbing, frequently a good choice. Most people start with an understanding that 'water' flows downhill, and can build from there.

Now if this was a cooking forum we could be talking about 'Master Bakers'

I like it.

Would like to add a question on the simple thinking: what will happend if our fellow use a 50sqmm instead of 0,5sqmm cable?

He will waste maney in cooper, have difficulto to connect it, and others on suports and space. But the cable will do the job.

Well from all your suggestions, what i got is that there will be no problem in using a cable size of high rating, for smaller current applications. It all matters in the expense and application, for smaller rating we have to use only cable corresponding to it. If we require an increase in length correspondingly we have to increase the size of the cable for a shorter voltage drop and power loss.

Here i have submitted the question with an example of 0.5mm2 so that everbody can understand what i m trying to ask.

If there is any thing wrong in what i understood written above, please correct me and add more suggestions if available. thank you...........

Sir,

Redfred gave a good point to consider in his #5 post. You need to look at the possible resistance of oxidation or bad connections, and make sure that the total resistance is less than the source's available voltage so it can drive the required amount of current.

Another point to consider would be the "signal/noise ratio". This has to do with the amplitude of the signal or current you are applying and how much noise or interference there may be from other sources. If your signal is low or the voltage driving it is low, then there is a greater possibility that it can be buried in induced or coupled noise on the wire. I have seen this happen in 4-20mA signals over telephone lines (as one example).

You are the only one in a good position to consider the importance of these two points, because your original question was in the form of a hypothetical.

--JMM

Well the minimum current is zero. Either there is current or there is none! Look at Lynn's hose comparision.

YES and NO.

The question is faulty first off, "current to conduct" is contradictory. One is the same as the other, and one cannot exist without the other.

Its possible to inject current in a cable and get nothing out the other end, if its AC and the frequency is such that the capacitive effects lose the current. that would be a function of applied voltage and capacitance. A VERY weak signal might be absorbed in the nearest insulator to the driven end. I dont know of any such application thats useful.

There would be a minimum energy needed to force a current flow through a conductor, but its extremely small, and a function of the voltage required to knock the first few valence electrons loose in the material to then allow conduction. Again, pretty much useless. Thats getting into semiconductor physics where its possible to inject electrons and lose them in the material.

Might make good University EE test questions.