What purpose you want this data?? This data its having more and more field work so its having valuable data for government departments. 

check the following links:

http://www.lib.umd.edu/gis/dataset

http://www.platts.com/products/gis-data-electric-power

Hi, 

As per my understanding, you'll have to contact the following State owned boards for the information you require:

http://www.wrldc.com

http://www.mahatransco.in/

This is the map for O&M offices in the state, from where you can procure more information. 

http://www.mahadiscom.in/maps/map_index.shtm

The western regional load dispatch center will have power maps, with substations, and 33KV/11KV  transmission lines. However, on the wrldc site, when you go to the 'about us' section, and click on 'power maps', it shows the message "This data has been temporarily blocked in public domain purely for security reasons.

Thank you."

Hence you may contact them separately and you will be able to get the data. On the other hand, Bihar State has a full on GIS coverage of the power supply grid with locations of substations and distribution. 

http://gis.bih.nic.in/

Hello,

you could have a look at the OpenStreetMap project.

http://wiki.openstreetmap.org/wiki/Power_lines

SInce,

Marc-O.

Thanks everyone for your input. Really appreciate it. 

Hello,

My response to this post seems to be quite late. But I would like to add one source to get shp datafiles for this, just in case anyone else intends to use it. I could not find description of the power lines however (what is the voltage level considered to filter out this data, the date when the data was extracted, etc.). But I hope it should be a good starting point.

http://osm2shp.ru/