When changing a DB on a TT

[chris day]

hello people

Never changed a DB on a TT system before, question is if all final circuits will have 30ma RCBO devices what (if required) RCD will I need to install on the meter tails supplying the DB.

The rod currently with the Earth to MET disconnected reads a healthy ze- 98ohms which is quite good for a TT, with earthing conductor connected parallel with paths give me 0.22zdb.

 

[ackbarthestar]

You will need to protect the tails into the metal CU. Usually a 100mA 'S' type BS EN 61008 RCD mounted next or near to the incoming supply.

 

[suffolkspark]

if using an rcbo ccu you just need to use a compression gland to hold the tails as they enter the board, if you are using a dual rccb you need to swap the main switch for a 100ma s type, and again use a gland...

the amount I'm coming across lately that have been change and neither of these things done is scary!

 

[Midwest]

When using RCBO's with TT supply, you need to consider this argument apparently;

TT systems and RCBO's - https://www.electriciansforums.co.uk/threads/tt-systems-and-rcbos.110727/