rcd on a tt system

[Baker1988]

hi ya i have a home work question which is:

What additional protection is required on a TT system, justify your answer, Stating what regulation from bs7671 requires additional protection.

I am sure that answer is a rcd but i just cant fine the reg that states that you need a rcd the closest i can find is reg 411.5.2 but it does not actually say you need on.

any help please

 

[bigbaddave]

What is higher on a TT sysyem as opposed to a PME system

 

[Baker1988]

What is higher on a TT sysyem as opposed to a PME system

Hi yes i know the ze and zs is alot higher on a tt system so the overcurrent device might not trip in the required time so you need to fit a rcd as you can have a ze of 1667 ohms and the rcd will still work but i can not find a reg that states this

 

[Bobster]

Look under additional protection.

 

[amptest]

Bigbaddave gave you the answer think also about disconnection times

 

[Baker1988]

i have looked at addition protection and dissconection times but does it say any where in the regs that you have to use a rcd in a tt system

 

[MDJ]

Read 411.5, your answer is in there to the original question

 

[Baker1988]

Read 411.5, your answer is in there to the original question

yeah that is the reg i was gonna put on down thanks