哪些接地电阻值不应大于30Ω?

哪些接地电阻值不应大于30Ω?

["\u96f6\u6563\u7684\u63a5\u89e6\u7f51\u652f\u67f1\u63a5\u5730\u7535\u963b\u503c\u4e0d\u5e94\u5927\u4e8e30\u03a9"]