R
risk88
Hi all,
I'm a quite a new tester and still gaining knowledge and experience in the area from my work-mates, but I have a question they struggled to answer and agree on, or provide information in the form of relevant regulations.
The question been:
We have a few 200A supplies at work in various different areas, these are BS88 200A fuses in the cut out, which then go into the meter, out the meter with approx 1m tails to a fused main switch. Now, we get a messured Ze at the main switch of 0.32 (TNC-S) supply (at one of the sites), would this in theory be the Zs of the tails meaning that the cut-out fuses would not disconnect in 5s inthe event of a fault? Would this lead to a failed 7671?
Is there any information relating to the matter which states that if the tails are under a certain length and they have appropriate current carrying characteristics this is acceptable due to the nature of the supply? With the DNO been able to provide upto 0.35ohm.
The main switch will disconnect, it's just the protection of the 1m meter to main switch tails I'm a bit confused about.
The DNO's and Circuits are in a stainless steel road side cabinet.
I hope this makes sense, I know I've rambled a bit.
I'm a quite a new tester and still gaining knowledge and experience in the area from my work-mates, but I have a question they struggled to answer and agree on, or provide information in the form of relevant regulations.
The question been:
We have a few 200A supplies at work in various different areas, these are BS88 200A fuses in the cut out, which then go into the meter, out the meter with approx 1m tails to a fused main switch. Now, we get a messured Ze at the main switch of 0.32 (TNC-S) supply (at one of the sites), would this in theory be the Zs of the tails meaning that the cut-out fuses would not disconnect in 5s inthe event of a fault? Would this lead to a failed 7671?
Is there any information relating to the matter which states that if the tails are under a certain length and they have appropriate current carrying characteristics this is acceptable due to the nature of the supply? With the DNO been able to provide upto 0.35ohm.
The main switch will disconnect, it's just the protection of the 1m meter to main switch tails I'm a bit confused about.
The DNO's and Circuits are in a stainless steel road side cabinet.
I hope this makes sense, I know I've rambled a bit.
