Science question, might bore most!

[RF Lighting]

Yeah, alot of the poles round here have fuses like that to protect the supply cable.

3 phase supplies have three fuses on top of one another going up the pole.

 

[efiste2]

"HV systems don't have a Neutral or Earth, just 3 phases." thats not quite correct. At the primary 33/11kv substation the 11kv side of the 33kv to 11kv transformer has a NEUTRAL termination that is connected into a NEUTRAL EARTH cabinet that earths it down to the earthing sytsem of the substation. This creates the earth fault path return for the 11kv distribution system.............