Which characteristic does a low voltage holiday detector NOT have?

A low voltage holiday detector is designed to identify holidays, or discontinuities, in coatings that may compromise their performance. The characteristic that a low voltage holiday detector does not possess pertains to its ability to be used on coatings that exceed a certain thickness.

When coatings are thicker than 20 mils, a low voltage holiday detector may not effectively detect discontinuities because the voltage settings are typically calibrated for thinner coatings where the electrical path can easily reach the substrate. Therefore, this characteristic correctly identifies the limitation of low voltage holiday detectors regarding the thickness of the coatings they can evaluate.

Other characteristics such as having a ground cable attached directly to the substrate enable proper functioning of the detector by providing a return path for the electrical current. Additionally, utilizing a sponge saturated with a solution aids in ensuring conductivity, which is necessary for accurate detection. A maximum rate of 1 linear ft/sec double stroke ensures that the testing process remains consistent and thorough.