The Prospective Fault Current Clarification!

[JohnnyHS]

Hi guys,

I’m generating the company forms for the electrical installation certificate schedule of test results to the 17th Edition BS7671:2008 and have the following questions/statements that you fine sparkies may confirm/clarify for me...

The Prospective Fault Current

This was measured by a test engineer (who had the test equipment to measure this) from a contractor and the figure was 0.68kA. As this figure is measured at the main distribution board incoming Ipresume, for any future installations connected to this main distribution board for testing can I use this figure for future Prospective Fault Current values rather than having to measure this again?
And how do you measure this anyway!?


Johnny H-S BSc(Hons) MInstMC

Engineers like to solve problems. If there are no problems handily available, they will create their own problems.

 

[ScottyUK]

You got it. Our public utilities operate solidly earthed 400/230V systems. Residential premises rarely require a 400V 3-phase service although there are cases where they do have such installations.

Yes, a 1MVA transformer at 208/120V would certainly deliver some punch if a fault occured.


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