What is more effective for an organization, In-house training department or External Consultant?

In-house training is more effective,the main advantage to the organization of using internal coaches is that they do not have the direct costs that hiring an external coach would. Also, as the coachee's direct manager you already spend time with them and the coaching role provides you with the opportunity to get to know them well, whilst you build and demonstrate a foundation of mutual trust and respect. In addition, because you are constantly interacting with your team you will have many more opportunities to influence them than an external consultant would have. 

In-house training by external consultants...