1)Before knowing effect of Ketu in 3rd house we have to know about ketu and 3rd house.
2) Generally 3rd house belongs to Strength, Younger siblings, Short travel, communication.
Ketu belongs to detachment, harsh attitude, etc.
3)Ketu belongs to concentration so when Ketu in 3rd house, native has great own concentration regarding strength means native is very brave and courageous. Native may has very strong physical strength and also has mental strength. As when native is very concentrate regarding own strength then he may be definitely gives fear regarding own weakness. Enemy get fears from Native. Ketu in 3rd house makes native very active. As native is quick in activities so native may be good player.
4)Ketu is natural malefic so 3rd house ketu is malefic regarding Siblings. Ketu belongs to detachment so there is detachment between native and siblings. If ketu is not well placed then it proves very bad regarding siblings.
5)Ketu in 3rd house is indicating native may be go traveling a lots. It may be short ,long or medium depanding on chart. Some time it may cause for Forigen travel.
6)3rd house Ketu is indicating native is very harsh way to communicate other. They are very quicker and volatile in communication.
7)Ketu is placed 12th from 4th house (Mind and Thinking mind House) so native may be a bad habits regarding misunderstanding of matter . So Native may be suffering from mental stress.
8)3rd House Ketu is indicating Native May be rich and earn good wealth and name or fame.
