Where to measure Ze

[malcolmsanford]

A 10mm Twin and Earth cable will be roughly 17mm x 10mm and a 16mm T+E is 20mm X 10mm.

The CPC will vary to which size cable you have.

 

[Big n Daft]

I can see daddy worm now:willy_nilly:

 

[Geordie Spark]

Sorry in advance for what may be a daft student question. Where should I measure my Ze? My mum has a TNCS system with the meter/incoming supply at one end of her bungalow. The CU is some distance away (I guess around 15m) and connected via T&E. Do I attempt to measure Ze at the incoming or at the CU. There is no obvious place at the meter to take a reading easily. On my course we always do it in the consumer unit but of course that's not real life.

I'm just wondering what size this bit of T&E is ....... and how big is the fuse "protecting" it.

 

[mickys86]

i can see daddy worm now:willy_nilly:

lol 

 

[moorman84]

I would put a BS88 fuse instead of the isolator as it will give a higher maximum Zs. Also it the T&E running through thermal insulation as this greatly reduces the current rating of the cable. All of this should be taken in consideration when deciding the size of the fuse. For a TNCS system the minimum size of your earth cable should be 10mm.

 

[platty1005]

First thoughts Has the CU been moved at an earlier date ?
With 100A main fuse the meter tails should be 25 sqmm are they ?
What size is the T&E feeding the CU ?
Where is the MET ?
What size is the earthing conductor to the MET ?
Where are the protective bonding conductors terminated ?
What size are the tails from the meter to the isolator ?
How many ways on the CU ?
What is the estimated maximum demand ?