5
1-28. Latex rubber is a high-grade compound
consisting of what percentage of
unmilled grainless rubber?
1.
70%
2.
80%
3.
90%
4.
95%
1-29. Plastic insulation is normally used for
what levels of voltage?
1. Very high to high
2. High to medium
3. Medium to low
4. Low to very low
1-30. When dealing with NEC type designators
for thermoplastics, the letter "W" stands
for what type of insulation?
1. Oil-resistant
2. Moisture-resistant
3. Heat-resistant
4. Asbestos
1-31. When you work on synthetic insulated
wiring, what safety precaution must be
observed?
1. Wear protective goggles at all times
2. Avoid breathing the vapors when
the insulation is heated
3. Wear a dust mask in confined
spaces
4. Wear protective gloves if there are
cuts or abrasions on your hands
1-32. What nonmetallic material is most
commonly used to protect wires and
cables?
1. Rubber
2. Jute and asphalt covering
3. Fibrous tape
4. Fibrous braid
1-33. What is the common name for woven
covers?
1. Yarn
2. Loom
3. Fibrous tape
4. Unspun felted cotton
1-34. What percentage of tin is used in alloy-
lead sheathing?
1.
6%
2.
2%
3.
8%
4.
4%
1-35. Why is the use of asbestos being
discontinued as an insulating material in
the Navy?
1. It breaks down rapidly with
continued use
2. It is not as effective as other types of
insulation
3. It has not proven suitable for a
shipboard environment
4. It poses a health hazard to personnel
1-36. What happens to asbestos insulation
when it gets wet?
1. Its insulation resistance becomes too
high
2. It emits dangerous fumes
3. It acquires too great a dielectric
strength
4. It becomes a conductor
1-37. What insulating materials are best suited
for use with high voltage?
1. Thermoplastic and rubber
2. Varnished cambric and oil
impregnated paper
3. Teflon and silk
4. Silk and cotton
