Wiring Methods & Materials第 66 / 120 题
What is the minimum burial cover for rigid metal conduit installed underground in a location not otherwise specified?
a.18 inches
b.12 inches
c.6 inches
d.24 inches
解析
Rigid metal conduit and intermediate metal conduit are permitted at 6 inches of cover because the metal wall provides its own physical protection. Nonmetallic raceways listed for direct burial require 18 inches, direct-buried cable requires 24 inches, and 12 inches applies to GFCI-protected residential branch circuits.
法律依据: 2023 NEC Table 300.5免费刷完整 120 道题库 — 无需注册。
同考点相关题目
- A short raceway nipple no longer than 24 inches connects two enclosures. What fill percentage is permitted?
- Four 3/0 AWG THWN conductors, each 0.2679 square inch in area, are pulled into rigid metal conduit. What is the minimum trade size?
- What is the minimum cover for a direct-buried UF cable installed in a residential yard on a 120-volt, 20-ampere circuit that is NOT GFCI protected?
- What is the minimum burial cover for a nonmetallic raceway listed for direct burial without concrete encasement, installed under a lawn?
- A GFCI-protected 120-volt, 20-ampere residential branch circuit is direct buried in a yard. What is the minimum cover?
- How must electrical metallic tubing be secured and supported on a normal horizontal run?