Motor base grounding

I think the third one is more pleasing to the eye. As for the forced grounding of the shell, although there is a standard, it seems not to be detailed. Some posts have a lot of arguments, and I am a little confused. I look forward to the answer from the master.~

The second is more reasonable. The motor grounding point must be selected correctly. The electrical installation acceptance specifications and design drawings should clearly stipulate that equipment and metals that are normally non-energized should be clearly grounded for protection.

I was also confused at first. The motor foundation is already grounded or the cable has a grounding wire. Why does the motor need to be grounded? I think the more reliable specifications are 1. According to GB50257 7.1.1 In explosive hazardous environments, electrical equipment installed on grounded metal structures must be grounded (not the original text, part of the excerpt) 2. According to GB 755-2008 Ratings and Performance of Rotating Electric Machines, Article 11.1. For motors with an output exceeding 100kW, an additional grounding terminal needs to be installed on the machine base. For motors exceeding DC 1500V or AC 1000V, an additional grounding terminal needs to be installed on the machine base (not the original text, part of the excerpt) Therefore, I think whether the shell of a motor that has been grounded at the foundation needs to be grounded repeatedly depends on whether it is a motor with a grounding wire in the junction box in an explosion-proof area. Whether it needs to be grounded repeatedly depends on the power and voltage level. I hope other experts can see that Figure 2 is reasonable.

I was also confused at first. The motor foundation is already grounded or the cable has a grounding wire. Why does the motor need to be grounded? I think the more reliable specifications are 1. According to GB50257 7.1.1 In explosive hazardous environments, electrical equipment installed on grounded metal structures must be grounded (not the original text, part of the excerpt) 2. According to GB 755-2008 Ratings and Performance of Rotating Electric Machines, Article 11.1. For motors with an output exceeding 100kW, an additional grounding terminal needs to be installed on the base. For motors exceeding DC 1500V, AC 1000V, an additional grounding terminal needs to be installed on the base (not the original text, part of the excerpt). Therefore, I think that for motors whose foundations are already grounded, does the shell need to be grounded again? https://bbs.hcbbs.com/forum-174-1.html Check whether the motor in the explosion-proof area already has a grounding wire in the junction box. Whether it needs to be grounded again depends on the power and voltage level. I hope other experts can figure it out. Figure 2 is reasonable.

Personally, I don’t think either one is right. One for the pump base is grounded, and the other for the motor. There should be two grounding points.

Personally feel: 1. The foundation of the motor needs to be grounded ； 2. The motor shell generally also needs to be grounded, although the motor junction box has a special grounding wire for grounding. ； 3. The grounding wire should not be bent in a spiral ； 4. Grounding wires should not share grounding bolts.