EFLI on TT systems

[fengine]

This has probably been asked before.​

Can anyone explain to me why the maximum EFLI on a TT system to operate a 30mA RCD in the required time (table 41.5) is 1667ohms yet on a TN system, depending on the device rating ,table 41.3 is max of 15.33ohms (Type B 3A rating) I am aware of NOTE 2 200ohm

 

[BillR3]

The 30ma device which is quoted as 1667 ohms is a 61008 and does not have over current protection. The 60898 and 61009 both have over current protection and hence require a lower Zs reading to operate in the time scales given in the tables.

Hope this helps.

BillR3