M
MBEINST
Hi Gents and ladies,
I have been asked to quote on installing a couple of extra socket on a TT system.
When checking the existing installation my Zs readings on the ring are coming out at 39.8 Ohms (most remote). This is unacceptable (table 2d OSG). I then checked Ze readings which are coming out at 37 Ohms.
I'm relatively new to the game and never dealt with a TT system before, so went back to my books and have an hand written note in my 2391 notes stating 21 Ohms for TT system? Can't remember why I wrote this but assume it referred to the max Ze allowable for TT system. However OSG under Earth Electrode Resistance states 'if being used with an RCD should not exceed 200 Ohms'. I'm dealing with an old installation and no sign of RCD protection. Can't convince the customer to upgrade Consumer Unit.
It looks to me like this is going to turn into a major job and obviously I don't want to quote for a couple of extra sockets to find out that I need to put in another rod.
Any help to nurse this TT virgin through would be greatly appreciated.
'The best friendships are built on a solid foundation of alcohol, sarcasm, laughter and a dislike of the same people.'
I have been asked to quote on installing a couple of extra socket on a TT system.
When checking the existing installation my Zs readings on the ring are coming out at 39.8 Ohms (most remote). This is unacceptable (table 2d OSG). I then checked Ze readings which are coming out at 37 Ohms.
I'm relatively new to the game and never dealt with a TT system before, so went back to my books and have an hand written note in my 2391 notes stating 21 Ohms for TT system? Can't remember why I wrote this but assume it referred to the max Ze allowable for TT system. However OSG under Earth Electrode Resistance states 'if being used with an RCD should not exceed 200 Ohms'. I'm dealing with an old installation and no sign of RCD protection. Can't convince the customer to upgrade Consumer Unit.
It looks to me like this is going to turn into a major job and obviously I don't want to quote for a couple of extra sockets to find out that I need to put in another rod.
Any help to nurse this TT virgin through would be greatly appreciated.
'The best friendships are built on a solid foundation of alcohol, sarcasm, laughter and a dislike of the same people.'