ELCB tripping

<...touch the neutral to the earth, the ELCB is not tripping. why?...>

Because the imbalance of current between live and neural is <30mA at the moment the test is carried out.

Most ELCBs have a test button. Simply press it!

You are right. Manually the ELCB is tripping. If by chance, if there is any damage to skin of insulation, the leakage current may harm the personnel using the electrical equipment. We want to checkt the electrical tripping of the ELCB

REgards

PG

Please note that even what you call "Manual Tripping" is, in fact, only electrical tripping as far as the ELCB is concerned. Because, when you press the TEST Button, you are actually simulating the earth leakage conditions 'electrically'.

If your intention is to "TEST" the functioning of the ELCB by actually subjecting a person to electrocution, I doubt if anybody would be ready to undergo such a test.

The manual button does this by introducing an unbalanced load within the equipment.

To check outside the equipment, simply connect a load >30mA to the live conductor downstream of the ELCB, and to the neutral conductor upstream of it.

DG is earthed - both neutral and body.

Then why the touching of neutral to earth will pass the current (both at equipotential?) unless the cable length is long enough to have some resistive drop, enough to carry the 30ma current.

There has to be a current imbalance on the live and neutral feeding the load, both conductors passing through the ELCB, for the ELCB to operate.

ELCB or RCD?

http://en.wikipedia.org/wiki/Residual-current_device