Electrical evaluation of drum extension cables with HIOKI RM3542A

[Kiriakos GR]

Inspection & Safety tests for Drum Extension Cord


Especially for Field electricians all latest information’s and changes of latest electrical standards, they come late or not at all in our awareness’.

One important tool that we use its and every day this is Drum Extension Cord.
Inspection of Drum Extension Cord this must be frequent because this is heavily abused mechanically in several ways.

Its and every Drum Extension Cord this has product label, abuse due overload regarding current, this is not easy to happen in the hands of true electrician.

Mechanical abuse this is unseen enemy here, cable damage usually occur due unhappy trainee electricians which they do not pay much of attention when they deploy extension cord from point A to point B.

Additionally mechanical abuse can happen at female sockets, after inspecting my own Drum Extension Cord I did discover that inside the drum, one of four sockets this has broken one ground to earth clip of the two.

Third issue could be extension cord plug it self, at schuko plug both ground to earth side clips, they do fill up with dirt and dust and formed oxidation this is another unseen enemy.

Electrical inspection of Drum Extension Cord this can not be accurately measured by low cost multimeter, according to latest directives minimum resistance of PE wire, according to DIN VDE 0701-0702 should be 0.3 Ohm and 0.1 Ohm should be added for every addition 7.5 meters of cable.
The resistance, however, should not exceed 1 Ohm.

My own Drum Extension Cord this is 33M long, I did abstract 5M from 33M = 0.3 Ohm, and I did divide additional 28M / 7.5M (number) = 3.73 x 0.100 Milli-ohm = 373 Milli-ohm.
Complete sum this is now 0.3 Ohm (300 milliohm first 5M) + 373 milliohm (other 28M) and new total this is 600 milliohm (0.6 Ohm).

All numbers above clearly indicate that measuring equipment's capable for such measurements’ they could be only two.
1)   Insulation tester this includes low Ohms range.
2)   Bench top precision milliohm meter 
Such meters can do the measurements’ when we wish periodic inspection, heavily damaged Drum Extension Cord this would be at measuring range of handheld multimeter.