Hi, have problem
Currently a metal DB with failing RCD installed
3 phase TT supply
Need to change DB for Double insulated IP rated with 100A 100mA TD RCD
Problem is .... a time delay RCD trips with 0.13s-0.5s but under 17th edition, it must trip 0.07secs as i understand from Table 41.1 (Page 46 BS7671)
Table states that the times are for 2x rating of RCD so ... 100mA Time delay trips in 0.06-0.2 secs at 200mA fault ( Page 243 Table 3A)
This is only just on the limit if i happen to get a lucky rcd ...
Most circuits will be single phase on 30mA RCBOs but one is 3phase 16Amp and cant find 3phase rcbo .. the 100mA will cover this
Is there something i dont understand or doing wrong ?
Should i be using design voltage of 230v even though its 240v to earth?
If i said its 230v i can have 0.2 secs disconnection time on TT
any help appreciated
thanks
Currently a metal DB with failing RCD installed
3 phase TT supply
Need to change DB for Double insulated IP rated with 100A 100mA TD RCD
Problem is .... a time delay RCD trips with 0.13s-0.5s but under 17th edition, it must trip 0.07secs as i understand from Table 41.1 (Page 46 BS7671)
Table states that the times are for 2x rating of RCD so ... 100mA Time delay trips in 0.06-0.2 secs at 200mA fault ( Page 243 Table 3A)
This is only just on the limit if i happen to get a lucky rcd ...
Most circuits will be single phase on 30mA RCBOs but one is 3phase 16Amp and cant find 3phase rcbo .. the 100mA will cover this
Is there something i dont understand or doing wrong ?
Should i be using design voltage of 230v even though its 240v to earth?
If i said its 230v i can have 0.2 secs disconnection time on TT
any help appreciated
thanks