Motor foundation grounding
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The factory uses a TN-S power supply system; the protective wire inside the motor terminal box is connected to the PE conductor, and the motor casing is grounded again on-site near the foundation. Is it necessary to ground the steel foundation into which the motor is embedded? Which standard specifies this?
First of all, the motor housing must be grounded; the building foundation can be used as a grounding device for this purpose (the foundation on which the motor is mounted must be connected to the building foundation). Since the motor’s ground wire is buried deep underground, the resistance between the motor and the ground is much higher when the motor comes into contact with the ground, which is unsafe; therefore, a ground wire is necessary.
Refer to GB50169-2006: The frame or metal enclosure that supports electrical equipment.
GB-50169-2016 – Code for Construction and Acceptance of Grounding Systems in Electrical Installation Projects. I actually have the latest version of this code, but I haven’t studied it in detail. 3.0.4 states that the following metal parts of electrical installations must be grounded: 1 The metal bases, frames, enclosures, and driving mechanisms of electrical equipment. In bold font; these are mandatory provisions.