I suspect the IEC 60725 impedance is at the service entrance, not through the 
breaker box, building wiring, connectors, and power cord.  By the time all 
these resistances are taken into account, I suspect that the total resistance 
is at least twice that specified in IEC 60725.  


-----Original Message-----
From: Ralph McDiarmid [mailto:ralph.mcdiar...@schneider-electric.com] 
Sent: Monday, November 20, 2017 10:42 AM
Subject: Re: [PSES] Regulatory requirements for MOVs placed line-to-ground on 
AC mains ports?

According to IEC/TR 60725, 90% of customers in the UK and in Australia, will 
have electricity supply impedance less than or equal to 0.25 + j0.23 ohms.  
That according to a survey or residential service for 230V/50Hz

That tells me that short circuit current would be at least 680A, but could be 
twice that value or higher for some customers

Ralph McDiarmid
Product Compliance
Solar Business
Schneider Electric

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