Should companies ban social networks at work place?

Yes ! I am totally in favour to ban on it. They can use mail and other technology for the same

Unless they're in Marketing/Research: YES!

Eventually in the end it won't matter, as, if you'll deny the access through your server network at workplace, but still an employee can access it through his/her smart phones.

Social network can prove to be a source of distraction for employees, besides that ,we work in a information hyper-sensitive environment. Whilst it is important to have clear communications channels any form of negative publicity can get viral in no time.

Having said that instead of banning social media/network completely, organisations can have their own communication platforms , which can be used productively and constructively.

by the end of it , organisations can wave aside multiple social media platforms have one common internal social medium, thereby reducing the magnitude of distraction that various social media can cause.

54% of CIOs ban social media in the workplace as it relates to decreased productivity and IT infrastructure to handle the additional traffic and security issues for non‐related company business.
Nearly24% of Facebook users say they access the site “all the time” while at work, with35% admitting to accessing it occasionally.
Keep in mind that social media isn’t just Facebook access, but internet access to different applications such as twitter, blogging, email, text messaging etc.

No, if used for communication between staff and facilitate business only