DB to be located away from DNO equipment

[IAmSparkytus!]

Without the sub-main you would not be putting in a fuse to protect the DNO's fuse, so with a single sub-main simply extending it then the same surely applies?

This is my opinion on why you shouldn't need to downgrade the fuse.

 

[IAmSparkytus!]

Thanks for your help and advice pc1966. Have a good weekend ?

 

[pc1966]

And you!

 

[pc1966]

I guess I should point out for anyone reading that there might be other reasons to fuse down at the supply end:

• If 16mm SWA (or tails) are used for ease-of-wrangling reasons so not overload protected at 100A
• If the end of sub-main Zs is too high to allow 5s disconnection on a fault

To check if Zs is the issue, the OSG Table B5 has max Zs of 0.28 ohm for 100A BS1361 through to 0.53 ohm at 60A, though here a delay RCD of 300mA or similar would be an alternative to a smaller fuse if the CU is fully RCD/RCBO.

 

[bigspark17]

16mm ho7. Kmf with 80A fuse.

why are there 2 meters in the external box? Sounds like its a redundant meter or the old ec7 switch over. Id be doing my best NOT to have another external box.