ECA

Q & A of the Day - Can I use manufacturer's values rather than generic values in design?

Published: 8 April 2010 Category: Q&A

Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This Question of the Day, concerning electrical design and manufacturer's equipment values or generic values for earth loop impedance, is answered by the ECA:

Q & A of the Day - Can I use manufacturer's values rather than generic values in design?
Question: This is the scenario - when designing using Amtech, manufacturer's equipment is used rather than using generic equipment. The design passes and is compliant. The installation is then carried out and tested. When comparing the measured earth loop impedance with the generic values, the installation fails, but when compared with the manufacturer's values for the equipment used, it passes.

Is it acceptable to use the manufacturer's values rather than generic values?

Where in the regulations (BS7671:2008 or elsewhere) does it say that manufacturer's values can be used instead of generic values?

Answer: You can use the manufacturer's data instead of the data in Table 41.
The values in Table 41 are generic and are only a guide. The manufacturers will produce their own data based on the actual product specifications. Sometimes Table 41 does not have all the data and the manufactures would supply it. The data in regulations is a guide, so it is acceptable to rely on the data from the manufactures. This data should be able to be easily produced if challenged as to why Table 41 was not used.

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