I need some help from line men or eng. familiar with high voltage on this question.
An installation is going in that has 138 Kv primary service. There are uninsulated bus tubes (bars) from the disconnect switch arms to the top of the distribution panel. The bus tubes are four feet apart until the get to the top of the equipment and then they are reduced to being only 8 inches apart where they enter.
The bus bars inside the equipment is insulated, the ones coming in are bare.
Outside they are exposed to the elements, i. e. snow, rain, etc.
Is 8 inches of clearence enough at 138 Kv. ??
This is a customer owned installation and I can't find this in the NEC. Would the Life Safety Code have it ?
Any good formulas on clearence or sites would be appreciated.
Thanks.
Alan--Inspector
