请技术达人帮忙解释下面句子中的[size="3"][color="#000000"] [color="red"]separation walls [color="black"]是什么意思?怎样制作[color="red"]separation walls ?[color="black"]是结构专业来制作此墙吗?所需花费大概多少?
[color="#000000"]When cables of 3.3kV and above are jointed, [color="red"]separation walls [color="#000000"]are required in the cable [color="#000000"]joints.