100ma 100amp 3phase main switch on TT system and rcd protection on the rest of the circuits question

[andysparkfree]

Hi all , my question for your brilliant minds is (ill first set the scene)

35mm 4 core swa coming from an external supply, 16mm earth ran out to an earth rod(ze at the distribution board main switch 0.35ohms)
now this is quite a large installation with a 3phase distribution board in the basement which also feeds a 3phase distribution board on the ground floor, and this installation is a large domestic new build house

now the question is: currently all lighting and sockets as well as any circuits that are installed in twin and earth/ hidden in ceilings etc are covered by 30ma rcbos , however the following are only covered by the 100ma rcd protection of the main switch (external air-conditioning / lift supply and pumping station)(all just standard c type mcbs)

am i right in thinking thinking this set up is ok ? or do i need to replace the non 30m rcbo fed circuits with 30ma rcbos

thank you for any responses in advance

 

[Ian1981]

All 30mA rcds will be necessary for additional protection to circuits that require it , such as cables concealed in walls generally less than 50mm from the surface which are NOT protected with mechanical protection or contained in earth metal containment such as conduit etc.
Circuits serving special locations such as bathrooms,
Socket outlets upto 20amp and for mobile equipment not exceeding 32 amps.
The lift circuit for example if installed in swa will generally not require additional protection and if a TT installation then the 100mA rcd will be for fault protection only tho not ideal as a main switch, tho will offer some discrimination to the 30mA rcbos if it’s a S type rcd.

 

[Leesparkykent]

What size breaker is protecting the external aircon, lift supply and pumping station? Are these circuits final circuits or distribution circuits?

 

[andysparkfree]

sorry me bad the pumping station is 30ma protected as they needed 2 x socket outlets
lift is 16amp 3phase mcb ,swa fed radial
air con is 2 x 32amp mcb,3phase supply fed via swa
and 1 x single phase 3 core swa aircon radial
and also the sub main to the grd floor distribution is a 63amp 3 phase , fed with 25mm swa 4core with 16mm earth

think all C type(but would have to check the notes )