builders supply- amendment 3

[OldSparks]

Hi all
It is TT so at the meter position use a 300ma to 500ma RCD linked to a SPD in a plastic enclosure. DO NOT USE METAL AS THERE IS NO RESETABLE SAFETY CUTOUT BETWEEN THIS AND THE SUPPLY!! Any fault prior to the incoming RCD with blow the Supply Company fuse resulting in site black-out and a call out charge, not to mention blue language.
Earthing at this point must be to a dedicated earth spike and make sure the earth is good.
The SPD is necessary as if there is a lightning strike on the TT supply anybody working on rebar gets fried!
The choice of DBs after this is up to the installer.

 

[OldSparks]

By the way I am not new to EF I first posted in 2015 and am EEB trained and working in the industry since the 1960s

 

[cliffed]

Hi all
It is TT so at the meter position use a 300ma to 500ma RCD linked to a SPD in a plastic enclosure. DO NOT USE METAL AS THERE IS NO RESETABLE SAFETY CUTOUT BETWEEN THIS AND THE SUPPLY!! Any fault prior to the incoming RCD with blow the Supply Company fuse resulting in site black-out and a call out charge, not to mention blue language.
Earthing at this point must be to a dedicated earth spike and make sure the earth is good.
The SPD is necessary as if there is a lightning strike on the TT supply anybody working on rebar gets fried!
The choice of DBs after this is up to the installer.

Probability of the fault scenario ,quite small,using appropriate cleats etc,would minimise this,still a metal DB for me.

 

[OldSparks]

It is also unlikely the the Distribution Company would allow a TT supply into a metal cabinet for the same risk reasons

 

[cliffed]

Disagree