I believe they are:
Pin Insulators
Suspension Insulators
Strain Insulators
If thats not enough theres also insulators commonly used of lower voltage which are:
Stay
Shackle
Work with your units:
1 watt-hour = 1 (joule/second) · (hour) = 1 (joule-hour / second)
(1 joule-hour/sec) · (3600 sec/hour) = 3600 joules
So 1 watt-hour = 3,600 joules
A. it can be modified or rejected