Earth ground question

[MfgeEngr]

Hello,

I am new to UL regulatory details.

Question is regarding products with detachable power cord.

1. Is Grounding symbol/label required in the location where the ground wire secured from power receptacle in the unit? Some product have ground label some don’t, in the location where ground wire from main power receptacle is connected. I know it is essential for product with non-detachable power cord. Please clarify. But I find the ground symbol right next to ground lug that is protruding out of chassis.

2. Do we have to link locations where ground wires are secured to chassis and ground stud that is protruding out using a separate green/yellow wire? If yes, what is the order in which the linking wire be secured? (Should the wire be secured along with the ground wire from power receptacle using single serrated washer nut or be secured using individual serrated washer right after ground wire from power receptacle is secured first.) Can we avoid the wire if the location where grounding wires are secured to chassis and the location where ground lug that is protruding out of chassis are masked to have contact with bare metal?

Thanks.

 

[yasky]

I'd suggest a quick view of the NEC (National Electrical Code, or NFPA 70) and UL 508 if you have an industrial product (not sure if there's an equivalent consumer product standard, sorry), for grounding requirements. Typically, a ground connection needs to be identified as such, and there are several ways to do this (ground symbol, words "GND", color coding, etc.), which may depend on the type of device/equipment. You should have a common ground in your device so that any ground points are already connected ("linked") without any need for additional connections. If you have separate grounds in your device for whatever reason then each ground plane/path needs to be evaluated to its relevant requirements. If you tell us what type of products you are working with others may have better input. Good luck.