can someone please explain?

[Darkwood]

On this occasion he design may be out of the scope of the BS 7671 and subject to other reg's i would ask him without fear of looking stupid and say you cant find and Reg' that would suggest his requirements except if he designed it his requests need to be met as it rises above the BS 7671 as its classed as manufacturers instructions... only reason i can think is hes more use to designing for a larger scale etc from larger supplies to building may require bigger earthing systems but certain areas of the design may mean isolated pipework through insulated gaskets and possible that it been fitted say in a garden may fall out of the equipotial zone and P.D.s may exist between supply earth and the ground it sits on.

 

[Dean Williams]

the way he said it was along the lines of: if water from jacuzzi was to splash onto motor, then water would have a potential which may not be enough to operate mcb/rcbo/fuse, therefore a larger earth is required, typically 16mm or 25mm

 

[needasparks]

Still can't get my head round it needing to be bigger than the phase supply to it.

 

[Dean Williams]

would it have anything to do with the resistance of the water in the jacuzzi, like if the water resistance is lower than the earth resistance

 

[Engineer54]

I fail to see why you would install a bigger CPC than the phase conductors?? What on gods earth is the added protection of a 16/25mm CPC going to give you??

Most Jacuzzi control panels now incorporate integral RCD protection too!!! lol!!

 

[leckyant]

Beats me man. Why don't you suggest 1/2 a dozen 1 milli amp RCDs in series

 

[spark 68]

The only time it may need to be larger CSA that I can think of, is if it is a combined CPC and bonding conductor for PME/TNC-S, and you are extending the zone

 

[telectrix]

the way he said it was along the lines of: if water from jacuzzi was to splash onto motor, then water would have a potential which may not be enough to operate mcb/rcbo/fuse, therefore a larger earth is required, typically 16mm or 25mm

which would seem to suggest that he reckons that copper less than 16mm has a higher resistance than water.

 

[Engineer54]

the way he said it was along the lines of: if water from jacuzzi was to splash onto motor, then water would have a potential which may not be enough to operate mcb/rcbo/fuse, therefore a larger earth is required, typically 16mm or 25mm

Total hogwash!! lol!!

 

[Inteificio]

the way he said it was along the lines of: if water from jacuzzi was to splash onto motor, then water would have a potential which may not be enough to operate mcb/rcbo/fuse, therefore a larger earth is required, typically 16mm or 25mm

So if water (which is a lousy conductor), splashes on to a motor (which would be IP rated), the difference of a few milliohms of conductor width will be affected but the few thousand ohms of water path.

Seems implausible to me, but then again i often overlook stuff.