This is an international forum and there’s lots of ways of describing the same thing around the world. It could help if you’d define: TP&N and pillar fuse. I may or may not know what either is, but I certainly don’t using those terms. You might also define “substation” since 200A and substation don’t really go together in my world.
Country is UK. TP&N = Three phase and Neutral. 415v line to line / 240 v line to neutral. When I say 'substation' I am referring to the final distribution point in the network = LV substation. Property is in a commercial area with each property having it's own supply cable from the LV substation. In the LV substation there are fused feeder pillars which feed individual properties (see image example). My question relates to the fuse ratings on the feeder pillar. On a 200a supply (200a fuses in the commercial property) would you expect the feeder pillar fuses to be the same rating or higher?
That is a good question- and to be honest I have no idea even though I should already know this. I'm actually mad at myself lol.
But- in theory there would be no issue except selective coordination- a fault between the main fuse and consumer board will take out both the main and pillar fuse if their time current curves cross or touch at any point in the fault spectrum.
There are several UK forums you can ask. In the mean time I know of several UK engineers who post here and hopefully they will chime in soon.
