| 摘要 |
To protect conductors laid underground from work being done in the ground, at least one cable or pipe is laid on either side of the conductor, but much closer to the ground surface, so that the workman or driver of a digger can be warned of the proximity of the conductor. The cable or pipe is made from steel so that a clear resistance is felt by the workman or machine driver when it is moved. The cable or pipe has a protective coating against corrosion and the steel is a high-grade one. Each cable or pipe is between eight inches and a foot above the highest point of the conductor and they are about one or two yards apart sideways.
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