INTRO2U.com :: BAD Insulation GUIDELINE REVIEW

The following table shows some of the causes of bad insulation and the tests that often detect them.

Bad insulation caused by...	Could be detected* in test as...
	Short	Intermittent Short	IR Failure (leaking)	Dielectric Breakdown (arcing)
Extraneous wire	X
Mis-registration in IDC connectors (tines have destroyed insulation).	X	X		X
Solder bridges	X	X		X When a small air gap exists
Wire insulation that has been damaged and pierced due to compression (cable ties, strain reliefs), heat (heat shrinking, soldering), or stripping (to inner conductors during outer jacket or shield removal).	X	X		X When a small air gap exists
Loose strands of wire outside of termination	X	X		X
Loose metal particles such as metal flake or cut strand of wire	X	X		X
Combination of leakage and arcing between layers of insulation				Partial Breakdown
Burn/carbon trail from breakdown; also some flux residue	Only with severe carbon trails		X	X
Ionic contamination like salt or RMA flux on connector body			X
Hydroscopic plastics/insulators that absorb moisture in humidity			X
Plywood and most phenolic materials (as often used in fixturing), but only if used as an insulator for connections.			X
Fixturing to the device under test that has any of the problems above	X	X	X	X

*Based on severity, test may or may not detect defect. Tests are not 100% effective in detecting all of the defects.

Causes of Bad Insulation