Star and Delta Connected Lighting Loads

Electrical Technology

Star and Delta Connected Lighting Loads – Electrical Wiring Installation

Star (Y) Connected Lighting Load – Electrical Wiring

A Star connected (Three Phase Four wires or 3-Phase, 4 wires) lighting system in a multi-storey (three Storey) building is shown in fig a. for uniform load distribution among three phases without being affected by random switching ON and OFF or burning lamps in the connected network, it is mandatory to have a Neutral wire to do the job (As Neutral point available in Star Connection).

Good to Know: We may obtain Single Phase and Three Phase Supply System (for different loads and purposes such as 1-Phase and 3-Phase lighting, Motors connection and other home appliances loads) from Star Connection because there is a Neutral point or wire in Star Connection.

It is shown in fig a that star network supplies two flats on each storey of the three storey building and the distribution of lamp load among three phases is balanced. There are fuses on Single phase supply at the flat entering cables to protect the others flats supply and two mains from short circuits in the same building. Did you note that there is no fuse on the neutral wire of the Main supply system?

Why there is no fuse on the Neutral of the Mains supply?

There is no fuse on the Neutral of the Mains supply because blowing such a fuse due to short circuit would mean a break in the neutral wire which disconnect the single phase supply as well as system would be unbalanced i.e. there would be unequal voltage across different lighting networks e.g. lamps in case they have different power rating. As a result, lamps in one group of lighting system would burn too bright whereas the lamps in other groups would burn dim which cause to reduce the life of the bulbs.