Off grid consumer unit protection query

[SSE]

I’m at a house just now, the guy has decided to go off grid, got a company in to take care of all that side of things. There’s a shed outside with all singing all dancing off grid solar kit (looks like the inside of a space ship!). The company took an SWA supply from there into the property & fitted it into an isolator from which I’ll take rails into the consumer unit. The supply from the shed is protected by an RCBO which is needed as it’s a TT system. I usually fit RCBO’s on all circuits but got me thinking, is there any need to fit RCBO’s in the new consumer unit with the main supply being already RCBO protected. Would it matter if the RCBO’s were fitted or is best practice to fit MCB’s in the consumer unit? First TT system I’ve worked on.

 

[littlespark]

Not worked on TT myself so not entirely sure a main rcd is required… or if it is, it is either time delayed or rated to 250mA as apposed to 30mA for the final circuits.

Seems pointless having 2 x 30mA in series, so to speak.

 

[Tom256]

RCD protection is used to fulfil which requirements of BS 7671?

 

[brianmoooore]

Depending on the earth resistance of the earth rod, I'd fit a 300mA delayed RCD in the shed and a house CU with all 30mA RCBOs.
A single 30mA RCD in a remote location is not a good idea.

 

[brianmoooore]

Good God, two posts jumped in, in front of me while I wrote my post. Don't recall seeing the "another post has been made on this thread. Read it?" warning pop up. Is that a victim of the forum reboot?

 

[littlespark]

Well spotted, Brian.

Will make @Dan aware

 

[brianmoooore]

May be a false alarm. I've just been contributing to another thread, and this time it did appear.