Do my tails need an rcd?

[hoover]

Hi all could someone please clarify if i need to protect via an rcd, the cable (split con centric cable) supplying the fuse board which will be run in an under ground duct about 8 meters long from the meter/incomer. The system is a tt system and i will be protecting the sub mains with a 80 amp sw fuse. There will be 30 ma rcds protecting the fuse boards so no problem there its just the sub mains cable im not sure about. Cant seem to find clarification anywhere in the 17th ed and was hoping someone could throw some light on it. Cheers in advance.

 

[SirKit Breaker]

You dont need a RCD to protect your tails. Make sure that your switchfuse is within 3 metres of your service fuse/supply head. if you are on a TT system i would be tempted to fit a consumer unit with the 100 DP isolator and protect your circuits using RCBO's. Otherwise you will be fitting a board with a RCD incommer or a dual split load one which brings in all the involvement of loosing lots of circuits if one of your RCD's bombs out.

Cheers...........Howard

PS thats not to say there is no reason for you to protect your cable with a RCD if you wish, just make sure its higher rated than the ones protecting your circuits