For example, an industrial site has very different safety context to a school or swimming pool. That’s, regardless of the physical context of that site. However, the weakness with the ‘deterministic’ approach was that a constant safety criterion was applied across all sites. Therefore, based on recognised international standards such as IEEE-80 / BS 7354 / BS 7430. The first really big step-change is the recognition that electrical system safety is probabilistic in nature.įor many years, engineers have used a deterministic approach to allowable step and touch voltages. BS 7430 Earthing Protection, was similarly updated in 2011. And supersedes BS 7354 (1990) code of practice for the design of high-voltage open-terminal stations. IEC based EN 50522 Earthing of power installations exceeding 1 kV a.c.
As part of the Earthing Calculations Design Safety brief. It’s still all too common to see this outdated measure of installed success appear on client/employer requirement specifications(ER’s).
If 1-ohm is still in circulation on your documentation then this section applies to you.Įven though the Earthing Calculations for determining a safe System Earth (Ground) has shifted away from an arbitrary resistance figure, usually <1 ohm. Earthing Calculations regarding your safety – you’re overdue an update!
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