Table 9. Insulation-Resistance and Voltage-Breakdown Tests 



Insulating Material 

 (15 mils thick) 



Insulation Resistance (meg) 



Voltage 

 Breakdown'^' 



Before Exposure i^ 



After Exposure^ 



Expose 



d About 0.5 Foot Above the Sediment 





Straight Wires 









Polyethylene 



20,100,000 



300,000 



Did not fail 



Polyvinyl chloride 



4,400,000 



1,200,000 



Did not fail 



Silicone rubber 



6,200,000 



12,000 



Failed 



GR-S (SBR)4/ 



5,500,000 



12,500 



Did not fail 



Neoprene 



36,000 



8,000 



Did not fail 



Coiled Wires 









Polyethylene 



20,100,000 



1,000,000 



Did not fail 



Polyvinyl chloride 



4,400,000 



50,000 



Did not fail 



Silicone rubber 



6,200,000 



50,000 



Did not fail 



GR-S (SBR)^ 



5,500,000 



10 



Did not fail 



Neoprene 



36,000 



20,000 



Did not fail 



Exp 



osed About 3 Feet At 



)ove Sediment 





Straight Wires 









Polyethylene 



20,100,000 



5,000,000 



Did not fail 



Polyvinyl chloride 



4,400,000 



725,000 



Did not fail 



Silicone rubber 



6,200,000 



230,000 



Did not fail 



GR-S (SBR)4/ 



5,500,000 



250,000 



Did not fail 



Neoprene 



36,000 



15,000 



Did not fail 



Coiled Wires 









Polyethylene 



20,100,000 



240 



Did not fail 



Polyvinyl chloride 



4,400,000 



45,000 



Did not fail 



Silicone rubber 



6,200,000 



150 



Failed 



GR-S (SBR)4/ 



5,500,000 



2,400,000 



Did not fail 



Neoprene 



36,000 



19,000 



Did not fail 



]_/ Average of eight tests. 



2/ Average of two tests. 



3/ Tested at 1,000 volts AC for 10 seconds. 



4/ Government rubber styrene (styrene butadiene rubber) 



41 



