The current that a load takes up comes into it from the live and returns through the neutral. We know that.

We test a live wire by touching it with a tester in one hand and being in contact with the earth. It GLOWS. But I tried to test a loads return current (my computer as the load having input power of 400W at 240V, so the current would be 400/240=1.67 A). I touched the neutral with a tester "A" and was in contact with the live wire through another tester "B" to prevent me from shock, and was completely insulated from earth with a pair of electrically insulated shoes. The "A" didn't glow neither did "B". Why could this be? But in this case when I measured the voltage between tester A and B it was 0V. Maybe that's why. Why could it be 0V ?

I know this question seems useless but I was curious to see the return current.


closed as off-topic by Leon Heller, Ricardo, Daniel Grillo, brhans, Rev1.0 Jun 18 '15 at 7:12

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  • 1
    \$\begingroup\$ Stop messing with mains before you hurt yourself. \$\endgroup\$ – Matt Young Jun 12 '15 at 18:06
  • 5
    \$\begingroup\$ Such dangerous questions should be closed. \$\endgroup\$ – Leon Heller Jun 12 '15 at 19:23
  • \$\begingroup\$ well i take proper precautions before doing this. with an ammeter on either side you can see readings. but the tester is the thing that makes me mad. \$\endgroup\$ – techloris_109 Jun 12 '15 at 21:46
  • \$\begingroup\$ It would appear you shouldn't be going near mains voltages, & certainly not poking around with them as you describe. \$\endgroup\$ – Techydude Jun 13 '15 at 2:55
  • \$\begingroup\$ yes i understand this really seems dangerous. thanks all \$\endgroup\$ – techloris_109 Jun 13 '15 at 5:54

The tester in your hand indicates live voltage is present. It doesn't indicate current thru the load. You need an ammeter for that and, it works in live and neutral.

But in this case when i measured the voltage between tester A and B it was 0V

You said A was connected to neutral and B connected to live. This means that the AC voltage between A and B is 240V or the power feed was switched off. Are you sure you are measuring with your meter on AC and not DC?

  • \$\begingroup\$ No, the load current does not flow your tester. The current that flows thru your tester is what flows thru your body due the voltage supply, the neon and the limiting resistor. If several amps of load current were flowing thru your body we wouldn't be having this discussion and you'd be in a mortuary. You probably connected your meter to the electrodes that your body touched. If there was no load connected you'd still get a glow in the tester so have I convinced you yet? \$\endgroup\$ – Andy aka Jun 12 '15 at 21:29
  • \$\begingroup\$ yeah my meter was in AC. Even a 240V b/w neutral and live there is a voltage and as you said tester being voltage indicator shouldnt the tester glow.In a tester we have a neon bulb in series with a resistor to limit current. Since current is there in live and since it flows through the bulb it glows. isnt it. then why cant we see the return current. When a tester is connected to live i guess you wont a get a 240V b/t tester and ground it probably drops down to around 20V. So when there exists a 240V b/w neutral and live still it shows 0V (it should have shown some 20V) as i mentioned above \$\endgroup\$ – techloris_109 Jun 12 '15 at 21:33
  • \$\begingroup\$ Neutral is usually about a couple of volts from earth (your body potential for AC). How can you expect a 90V Neon to arc over in this scenario. The current flowing thru live to the load IS NOTHING to do with it (for the last time!). The load current DOES NOT flow thru the neon. If you had a pressure gauge on a tap on a sink would you expect that gauge to tell you the flow rate into the sink? Voltage is pressure, current is flow. If you don't follow this you need to ask a more basic question that can be answered properly. Consider starting a new question. Then come back to this problem. \$\endgroup\$ – Andy aka Jun 12 '15 at 21:38
  • \$\begingroup\$ hmm i guess your answer seems satisfactory. and yes the meter read 0V as my body was in touch with the electrodes. thanks Andy \$\endgroup\$ – techloris_109 Jun 12 '15 at 21:43
  • \$\begingroup\$ You've un-accepted this as an answer - is there a reason? \$\endgroup\$ – Andy aka Jun 17 '15 at 13:43

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