What can be the effects of unbalanced load distribution among three phases in a building?

Can it cause any problem to the Equipment s connected?

You can easily separate those from people who have been in the field, as distinct from those who may not have practiced their electrical engineering at the 'sharp end' - that is, in the field. All the views were relevant, though.

1. If you are faced with the negative effects of an unbalance 3-phased problem, the first sign is annoying tripping of protective systems like circuit breakers or alarms.
2. Usually this tripping will occur even when the highest current reading in one of the phases is less than the current rating of the supply source - say generator set. You could spend valuable time trying to find the faulty equipment or circuit. You won't find it - because there is none!
3. The imbalance will cause a resultant current to flow to earth, via the neutral point. Most protective systems monitor the level of current flowing through the neutral line. if this exceeds a certain level, the system will trip on earth fault.
4. The other noticeable effect is felt more in the telecoms industry - that is the harmful effects of harmonics.
So, if you don't want to lose your hair, keep your circuits balanced!

Unbalanced loads cause crappy power factors, and will effect the peak demand billing by the supplier, you will probably pay a much higher rate.
The neutral in a 3 phase system caries the differential in load, and as in most cases the "neutral conductor" is the same size as the phase conductors you will never get oerheating???????
Wow??? and the volt drop?? please take into account cable distance when designing airconditioning or any other circuit for that matter, and you should never have voltage dropp (in an ideal world, agreed) but the levels should never xceed 10% anyway if correctly designed Bla Bla Bla, Uh waht was the question again?????
I will let all you experts tackle that one!!!!