I installed a Generac 200A ATS with a main Cir Brk adjacent to a existing Main 200A panel with a 2" rigid close nipple. The main bonding jumper is attached to the metal ATS enclosure. Why is it that the EGC bond wires have to be separated from the neutral bar when both of these metal enclosures are joined together by the rigid nipple and the neutral connections are one in the same? I can understand if I used PVC or SER between the two.What's the electrical hazard? I know the existing MDP is now called a sub panel but whats the difference if this ATS had circuit bro built in?
ATS adjacent to MDP
- Thread starter kec
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That's pretty much the reason in a nutshell. 250.24 prohibits any grounded-grounding connection after the service (with exceptions) and you ATS becomes the service.
There is no distance in the rule. A "sub-panel" on the 2nd floor is treated the same as one adjacent to the service. The primary purpose is to prevent unwanted voltages on the grounding conductors.
Any grounding electrode conductors in the existing 200m amp panel should move to the ATS also.
mkgrady
Senior Member
- Location
- Massachusetts
Because the nipple will carry some neutral current from the subpanel to the ats
electrofelon
Senior Member
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- Cherry Valley NY, Seattle, WA
Whats that song by Bruce Hornsby......Oh, "thats just the way it is.........." How about this: consider a non fused switch used as the service disconnecting means, and that nippled to an overcurrent protective device cabinet. In that would you bond the OCPD cabinet? I am actually not sure, Ill have to check that, or hopefully someone else will chime in and save me the trouble :angel:
There is an exception that metering equipment located on the load side of the service disconnect can remain bonded.
Sounds like this is an exception
Yes, GEC has been relocated to ATS
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
But your situation differs than the hypothetical one I proposed. The difference is with your the ATS is your service disconnecting means AND overcurrent protection. That is your service equipment. The panel is now a "sub panel". The way I proposed it, and why it may be different, is the service disconnect does not have overcurrent protection - it is installed adjacent to it in a separate cabinet. If you look at article 230, service disconnecting means and overcurrent protection are both types of service equipment. 250.24(A)(4) talks about a MBJ at the "service equipment."
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