Twin and Earth CPC

[davesparks]

Continuity but it would be a bit pointless proving it's of adequate size when we would already know it was.

Proving it is of adequate size is done by calculation before you start installing.

Zs proves continuity of the complete return path back to source using a higher current than is normally possible with a dead test.

 

[Mark Wright]

All I'm saying is if the CPC was the same size your concern that ADS could take place would be as much as your concern that a short Line to Neutral would trip the MCB - basically we don't even think about it because we know the Line and Neutral are of the same size so it doesn't even cross our minds we take it for granted.

 

[Ian1981]

All I'm saying is if the CPC was the same size your concern that ADS could take place would be as much as your concern that a short Line to Neutral would trip the MCB - basically we don't even think about it because we know the Line and Neutral are of the same size so it doesn't even cross our minds we take it for granted.

Unlike Line to neutral faults, line to earth faults increase the risk of dangerous mains voltage appearing on exposed conductive parts, which is why we are required to test that disconnection times are met and that earthing and bonding is correctly maintained through out the installation.
The regulations talk about that if a circuit downstream of an rcd is installed, then as long as continuity of the protective conductor is confirmed by adequate testing and that the rcd has been confirmed to provide ADS, then yes measuring earth fault loop impedance is not necessarily required on rcd protected circuits, regulation 643.7.1

 

[Mark Wright]

To me that's just all the more reason to use a CPC at the same size but anyway each to there own etc.

 

[Ian1981]

To me that's just all the more reason to use a CPC at the same size but anyway each to there own etc.

Which is fine if using any other cable than twin and cpc cable.
No ones going to wire domestic installations in conduit and singles tho are they?

 

[Risteard]

No ones going to wire domestic installations in conduit and singles tho are they?

I'd love to, but competing on price would definitely be an issue!

 

[Mark Wright]

I don't want to get bogged down but Ireland are now using T&E with full size CPC aren't they?

I mean I'm not bothered but from a safety point of view a full size CPC obviously makes sense that much I think we can all agree.

 

[Risteard]

I don't want to get bogged down but Ireland are now using T&E with full size CPC aren't they?

I mean I'm not bothered but from a safety point of view a full size CPC obviously makes sense that much I think we can all agree.

In the south, yes.

 

[davesparks]

I mean I'm not bothered but from a safety point of view a full size CPC obviously makes sense that much I think we can all agree.

From a safety point of view it doesn't make a blind bit of difference as long as the CPC is at least equal to the minimum size required by calculation.

And you still need to carry out a Zs test whatever size you use.

 

[Mark Wright]

Or course it makes a difference fault current should be carried away as quickly as possible.

and countrys that employee full CPC and adopted MCBs and RCDs earlier don't cry about sockets in bathrooms and carrying out Periodic Zs tests.

Skimping on CPC however you want to justify it, is cost over safety a practice that many countrys have left in the past where it bellongs.