Inspection method:
A layer of wrapping insulation wire depend mainly on the outside, time grows, corrosive gas corrosion, insulation to reduce gradually, slowly aging hardening, brittle or fall off, they can't afford to have the insulation effect. In fact, wire and cable is the most direct reason for premature failure of insulation to reduce breakdown. Small make up today will be a few moves teach you how to judge whether the wire aging, check in time, eliminate safety hidden trouble.
1, "down the wire to check the appearance, dark hair hard crack. See hands curved line insulation, stiff cracking skin." Refers to follow the wire insulation layer was observed, if discover the insulation color lose luster, dimming, harden, crack, parts fall off. Stiff wire bending insulated wires with both hands, and even insulation cracking, such as insulating layer falls off, it shows that the wire has been varying degrees of aging and serious aging.
2, "the accurate method to measure insulation megohm not low. Between two rain moisture value can be small, numerical again small half." Refers to the relatively accurate judgment line insulation condition available for electrical wiring insulation resistance meter, the measurement of insulation.
The insulation of the different routes have different minimum permissible value. For example, the use of household 220 v circuit, lowest 0.22 megohm insulation resistance; Rain wet value should not be less than 0.1 ohms, if measured insulation resistance value is less than the above numerical, shows that there is something wrong with the electrical wiring insulation.