for 400V Line-Line - use for triacs (even with L-N configuration - makes rewiring easier)
s20 K460 = 460V AC RMS
14D751K = VDR-0,6 460 = 460V AC RMS = 750 V peak
for 230V Line-Neutral - use for PCB connections
s14 k300 = 300V AC RMS
14d471k = vdr-0,6 300 = JVR14N471K = 300V AC RMS = 471V DC = 471 V AC peak
110V
s20 k275 = 275V AC RMS
This one will react very quickly and die prematurely. Not recommended, except for 110V systems
Design criteria
More Watts -> can withstand high voltage longer.
Higher volts -> this might be useful, if your system has lots of overvoltage spikes, and the MOVS burn quickly.
The triacs can withstand abolute max. 560 V AC.
However consider to find out where the voltage spikes come from, and try to reduce them.
If you suspect the voltage spikes come from a slow reacting IGC:
try to increase the P-Value.
Also from SW1.2.1 2018-01 onwards, there is a "direct" overvoltage protection mode, where all dump loads go on immediately, if an overvoltage condition happens.
For the variable triacs, this means really immediately.
For all other dump loads, this means at the next zero crossing.
You can also use mains line filters to reduce voltage spikes.
Search words on ebay: netzdrossel, surge filter, mains choke, mains filter, inductivity
See also Voltage ratings