Three Pole or Four Pole Breaker
Three Pole or Four Pole Breaker
(OP)
We have a building which is fed by transformer via main LV Panel, neutral of transformer is earthed locally,
Please suggest which one will be better
1.Three pole breaker at incomer of main LV panel with a neutral link and all downstream breakers Four Pole.
OR
2.Four pole breaker at incomer of main LV panel and Three Pole downstream breakers with neutral link.
Please suggest which one will be better
1.Three pole breaker at incomer of main LV panel with a neutral link and all downstream breakers Four Pole.
OR
2.Four pole breaker at incomer of main LV panel and Three Pole downstream breakers with neutral link.






RE: Three Pole or Four Pole Breaker
Switching neutral is generally considered a bad idea and at least not permitted in NEC, except in some source transfer switch/breaker or otherwise required for total isolation or some engineering reason.
Rafiq Bulsara
http://www.srengineersct.com
RE: Three Pole or Four Pole Breaker
Engineers are always honest in matters of technology and human relationships. That's why it's a good idea to keep engineers away from customers, romantic interests, and other people who can't handle the truth.
RE: Three Pole or Four Pole Breaker
RE: Three Pole or Four Pole Breaker
1. Transformer star point brought out to a link in the LV switchboard.
2. Neutral link connected to neutral bus.
3 Neutral bus connected to the earth bar via bolted link (For testing)
4. Earth bar connected to earth grid via bolted link (again for testing).
Therefore 4 pole breakers unnecessary.
4 pole breakers may have a place in certain circumstances but not on a standard LV distribution system.