This part of IEC 60099 applies to non-linear metal-oxide resistor type surge arresters without spark gaps designed to limit voltage surges on a.c. power circuits
SANS 60099-4:2007 history
0000 SANS 60099-4-2014
2009SANS 60099-4:2009 Surge arresters Part 4: Metal-oxide surge arresters without gaps for a.c. systems
2007SANS 60099-4:2007 Surge arresters Part 4: Metal-oxide surge arresters without gaps for a.c. systems