Transformer bushing spacing in oil?

[tyak]

Hi I am refurbishing a 14.7kv three phase transformer, pad mounted and I need to find out how far to space the bushings on the secondary connection between the phases and the tank (ground). The tank is filled with oil.
I have consulted my CSA standards and have only found tables for connections in air. I have also been searching the net with no luck.
Any help or direction would be great.
thanks,
T

 

[RRaghunath]

I think it is BS 162 for substations which has clearances in oil in a tabular form.

 

[jtkirb]

transformer oil is about 35kV breakdown for 1/8" gap. Most 12.47kv transformers I have seen have abourt 12" or more spacing on load break elbow bushings. More for substation style or live front.

Why would you be relocating the bushings on a refurb?