Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This Question of the Day, concerning Ze measurement at the origin of an installation, plus Zs of the main fuse at the cut-out, is answered by the ECA:
However, as I have taken the Ze measurement at the load side of the main fuse, would this value also be seen as the Zs of the main fuse at the cut-out?
I would imagine that if my Ze is greater than the maximum permissible Zs value of the main fuse, the main fuse would not disconnect within the required time, so I assume this would jeopardise the integrity of the protection for the meter/consumer unit tails. Is that so?
Answer: The Ze measurement should be taken at the incoming supply intake fuse or switchgear.
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