Why is split RCD not appropriate for TT?

[cireland]

It doesn't say required it suggests them.

It does say 'shall be used'.

 

[swaRRR]

It does say 'shall be used'.

It says residual current devices shall be selected to limit risk of unwanted tripping, and then goes on to list split load RCDs and RCBO's for consideration. It doesn't say RCBO's shall be used.

 

[mainline]

It does say 'shall be used'.

Regulation 531.3.2 (Unwanted Tripping) now points out the use of RCBOs for individual final circuits in residential premises as a method to prevent unwanted tripping of such protective devices.

 

[nicebutdim]

'Other than at the origin of the installation, every circuit...that may have to be isolated without interrupting the supply to other circuits should be provided with its own isolating device. The device must switch all live conductors in a TT system and all line conductors in a TN system.'

This basically says all breakers have to be double pole in a TT, no?

Yet you go to 132.15.201 which the OSG references and it says absolutely nothing about this.

The DP main switch makes it compliant.

I don't believe these two statements can be reconciled.

 

[mainline]

I don't believe these two statements can be reconciled.

It makes it compliant with regard to isolation

 

[westward10]

You said RCBO's were now required in residential installations.

Yes I did later I said 'suggested'.

 

[swaRRR]

Yes I did later I said 'suggested'.

 

[mainline]

It does say 'shall be used'.

And it should really say “Required”

 

[buzzlightyear]

NICEIC says you don't need a up front rcd
On TT main switch the rest of the board rcbo.

 

[mainline]

NICEIC says you don't need a up front rcd
On TT main switch the rest of the board rcbo.

Thats what the thread was about why it's ok with rcbos and not ok using split rcds.