These are typical metal roof in my country.. it's connected to iron c-purlins metal screwed to metal sheets. Our structural plans never have any grounding details of this. I'm just wondering what would happen if a live wire touch it or the I-beam connected to it (because we hang electrical wires under the roof), would the entire roof get electrified? and if a person on the other end touch it.. would he get electrified too.. or does it dissipate in large area like this? How do you compute the dissipation behavior of such area given a wire size and current?
And if you ground it (by connecting to the grounding system in the building with neutral connection to centertap of the outside transformer with rods stuck to the soils or when proper grounding is obeyed).. would this trip the circuit breaker? or would the large surface area present the tripping? What do you think?
An unrelated question. Supposed you need a 220-110v step down transformer with same impedance as a 5 meters wire of size 8 AWG. How do you compute how how big or small the transformer must be? Assuming the transformer needs to supply 4 Ampere.
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