DIN EN 61557-4:2007
1000V以下交流和1500V以下直流低压配电系统的电气安全.防护措施的测试、测量或监测用设备.第4部分:接地和等电势跨接电阻
Electrical safety in low voltage distribution systems up to 1000 V a.c. and 1500 V d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 4: Resistance of earth connection and equipotential bonding (IEC 61557-4:2007); German v