24vdc and rs-485 in same condiut

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seand27

Member
Location
cambridge, ma
Hello, Everyone!

We have a customer that is running 24vdc and RS-485 communications lines in the same conduit for a solar PV monitoring application. The questions is wheather the 24vdc needs to be grounded in this application? I have searched quite a bit and can't seem to find any best practices published on this topic. Does anyone have any thoughts on this? Much appreciated!!

Sean
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Hello, Everyone!

We have a customer that is running 24vdc and RS-485 communications lines in the same conduit for a solar PV monitoring application. The questions is wheather the 24vdc needs to be grounded in this application? I have searched quite a bit and can't seem to find any best practices published on this topic. Does anyone have any thoughts on this? Much appreciated!!

Sean

is the 24VDC a class 2 circuit?
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Hi, Bob.

Thank you so much for posting a response so quickly. Honestly, I am not sure if it is a Class 2 circuit or not, but I will try and confirm that. The device generating the 24vdc in this case is this Weidmuller power supply:

https://catalog.weidmueller.com/catalog/Start.do?localeId=en_DE&ObjectID=8739140000

If this is a class 2 circuit, should the 24VDC be grounded?

Cheers!
Sean

The power supply label that you linked to shows it is a listed class 2 power supply so it probably is a class 2 circuit. And equipment grounding conductor is not likely required. I am not real sure if you are asking if an equipment grounding conductor is required or if one leg needs to be grounded.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
There is no requirement in the NEC to ground one of the legs of the power supply output circuit. 250.162 covers if a DC system needed to be a grounded system, and you system is not required to be a grounded system.
 
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