Raymond asks this question, which is about an electric motor and inverter installation and what isolation system is likely to be necessary. It has been answered by SELECT (Theme - Power):
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Question: I am currently involved in a project to install inverters to control electric motors, and I am unsure of the requirements for isolation of the same.
The installation involves inverters at ground level to control motors at high level (approximately four meters above ground). I shall be fitting isolators and emergency stops at the motors but I am unsure as to whether I need to fit isolators at the inverters as well, given that the distribution board supplying the inverters will be within three metres of the units.
Please advise on the layout required for this installation in order to comply with BS 7671:2008.
Answer: For the requirements to isolate from invertor to motor for safety reasons, refer to BS 7671:2008 (2011) 537.2.2.2, 537.2.2.5 and 537.3.1.
As for the distribution board being within three metres of the units as you describe, depending on overcurrent and fault protection requirements, it might be necessary to isolate all live supply conductors. However, this may cause shutdown problems of all the final circuits pertaining to the distribution board.
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