Discrimination Regarding

Since most end loads will be motors, you can read up on Type 1 and 2 co-ordination in IEC 60947-4

Discrmination and cascading are types of coordination, about which there are a number of papers on the web. Also many tables published by manufacturers.

About the rating of the outgoing being less than half of the incomer, this is natural,isn't it? As otherwise, you can't have two outgoing feeders at all !!!

Now-a-days, you can easily have discrimination as variants of switchgear allow you to do so.

Discrimination is of three type 1. Current. 2. Time 3.Enegy.

By selecting the upper cascade feeder i.e. Incomer of same panel of outgoing of Main LT Panel. twice of O/G rating your are getting basically energy discrimination.

You can even have discrimination for current & time with same ratings aslo as in case of Outgoing of Main Panel which is feedeing to the incomer of any sub panel.

Hope you get the point.

:)

The rule of thump was 1.6.But when you go through other posts you will get a more accurate picture.

Aren't thumbs only for sucking?