How to recognize incoming earth systems quickly

[LeeJayyx]

Hey sorry probaly seems like a real amatuer question to a lot of you but im still in training (L3 2330) and have difficulty in telling a tnc-s from a tns. i know a TT is for rural locations and comes from an earth rod but is there any surefire way of recognizing tnc/tncs/tns quickly?
Thanks

 

[malcolmsanford]

Yes by doing you PSCC/PEFC tests. On a TNC-S they should be virtually identical, on a TN-S your PSCC will normally be higher

 

[mechelec]

Dont assume TT is always in rural areas. I have come accross them on council estates built in the 50's in towns

 

[JONOXNAM]

Hey sorry probaly seems like a real amatuer question to a lot of you but im still in training (L3 2330) and have difficulty in telling a tnc-s from a tns. i know a TT is for rural locations and comes from an earth rod but is there any surefire way of recognizing tnc/tncs/tns quickly?
Thanks

Just look at the incoming cable, if there is a braided soldered type connection on the actual supply cable sheath its TNS. Max Ze 0.8 as its uses the sheath of the supply cable and that is not copper.
If the supply cable enters into the cutout without any connection and there is either an earth sticking out if the side of the cutout or a terminal block on the side its a TNCS. Max Ze 0.35 this uses the Neutral conductor and is just a link in the cutout that you call the earth hence PSSC and PEFC should be very similar as its the same wire apart form the cutout end.
TT has no supplied earth connection only L+N and is not limited to rural areas at all. I have it in my house in a city of 350K population. Max Ze - 1667 however anything over 200 is said to be unstable.

Get used to drawing your EFLI for the 3 as there will be Q's in your 2330 exams and 2391 exams for sure.