TT supply - rcd needed

[monkey5]

evening all

just thinking abit too much and now confusing myself!

if you have a TT system do you have to have a rcd to protect the whole consumer unit, but surely this means fault on one circuit you'll lose power to everything.

or is it as long as all circuits are rcd protected by separate rcbos or dual board thats fine.

not yet worked on a tt system but sure i will in the future so would like to know.

cheers wayne

 

[paul b b]

TT's have a 100ma rcd as main switch, but if you put a new cu in just put a 17th with main switch and 2 rcd's

 

[NozSpark]

The only reg that applies is that all circuitis must have RCD protecton (to protect against fire and to protect livestock).. under the 16th ed that usually meant a split load CU with a 100mA S type (time delay) RCD as a main switch and then 30mA protection for things like d/s sockets & showers.

As the 17th ed requires that all circuits burried <50mm (with certain exceptions) and socket outlets <20A have RCD protection (30mA), then in a house this would mean that all circuits would have RCD protection and therefore fulfill the fire & livestock reg..

Note. even SWA, MICC and otherwise earthed mechanically protected circuits will still need RCD protection if its a TT installation

 

[monkey5]

cheers lads makes sense now