gkenyon:

ProMbrooke:

Right, but what has me perplexed are the lack of tables in part 7. Exception being medical locations however this should apply to all kitchens, bathrooms, laundry areas, garages, unfinished basements, exterior sockets, pool circuits and the like- anywhere skin conductivity is lowered typically through moisture or large earthed surfaces.


Bonding and RCDs should not be the primary means to achieve protection in these areas. Rather a pyramid approach should be taken imo. Remote earth is impossible to avoid in all scenerios. RCDs have much higher failure rates compared to MCBs. Yet ADS remains the most simple, assured and reliable way of protecting life and property.

Disconnection time may not be the answer, so that's why no tables.Where RCDs are specified, you're practically there already (0.04 s disconnection time OK for U0 230 V and your "Wet" table).


In terms of other locations, there is a need to take into account other issues, such as the clothing and footwear people are likely to be wearing etc - which change the touch voltages and disconnection times also. See IEC TR 60479-5:2007. IEC60479 : 2007 Effects of current on human beings and livestock –. Part 5:Touch voltage threshold values for physiological effects

I wish we knew their reasoning. IMO, 0.2 seconds is the answer in these locations should the RCD fail or where it can not be used reliably. BS7671 used to allow for skipping RCDs on circuits that can not tolerate inadvertent shutdowns.      

gkenyon:

ProMbrooke:

Right, but what has me perplexed are the lack of tables in part 7. Exception being medical locations however this should apply to all kitchens, bathrooms, laundry areas, garages, unfinished basements, exterior sockets, pool circuits and the like- anywhere skin conductivity is lowered typically through moisture or large earthed surfaces.


Bonding and RCDs should not be the primary means to achieve protection in these areas. Rather a pyramid approach should be taken imo. Remote earth is impossible to avoid in all scenerios. RCDs have much higher failure rates compared to MCBs. Yet ADS remains the most simple, assured and reliable way of protecting life and property.

Disconnection time may not be the answer, so that's why no tables.Where RCDs are specified, you're practically there already (0.04 s disconnection time OK for U0 230 V and your "Wet" table).


In terms of other locations, there is a need to take into account other issues, such as the clothing and footwear people are likely to be wearing etc - which change the touch voltages and disconnection times also. See IEC TR 60479-5:2007. IEC60479 : 2007 Effects of current on human beings and livestock –. Part 5:Touch voltage threshold values for physiological effects

I wish we knew their reasoning. IMO, 0.2 seconds is the answer in these locations should the RCD fail or where it can not be used reliably. BS7671 used to allow for skipping RCDs on circuits that can not tolerate inadvertent shutdowns.