ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Ever been afflicted by Gout?
by mbhydro - 09/15/20 05:50 PM
Questioning the electrical norms
by gfretwell - 09/13/20 01:17 PM
120/208 gives 240? please clarify
by NORCAL - 09/13/20 01:08 AM
Lock-down Thread
by Trumpy - 09/11/20 11:17 PM
Grounded metal cabinet?
by HotLine1 - 09/10/20 12:19 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 20 guests, and 13 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Bonding Rules 250.97, 2002 NEC #103169 05/10/02 12:18 PM
Joined: Oct 2000
Posts: 2,749
Joe Tedesco Offline OP
Member
QUESTION FROM: John J. Deery ,

Joe my question is about 250.97. If you run a branch circuit to a safety switch and the conduit enters the enclosure through concentrics or eccentrics, are you required to use bonding bushings when the voltage excedes 250 volts to ground and you pull an equipment grounding conductor and bond it to the enclosure?

My concern: "Is the conduit being properly bonded?"

I spoke to Kevin Huss from Square D at 800-634-2003 TEC support, and was told to date Square D does not have an enclosure on the market with pre-stamped ko's listed by U.L. for the purpose of bonding.

We have new branch circuits being run at our plant 480 volts where the conduits are being landed in pre-stamped ko's of Square D enclosures with equipment grounding conductors, but are relying on the eccentrics and concentrics to bond the conduits.

Thanks


Joe Tedesco, NEC Consultant
2017 / 2014 NEC & Related Books and Study Guides
Re: Bonding Rules 250.97, 2002 NEC #103170 05/10/02 03:12 PM
Joined: Mar 2001
Posts: 2,056
R
Redsy Offline
Member
The conduit needs to be effectively bonded to the installed EGC through a bonding bushing because if a fault developed in the raceway, the return path may not have a low enough impedance to assure opening of the OCPD.
Don,
are you wondering if the conduit is effectively bonded at the supply end, and therefore not required to be bonded through a bushing at the switch end?

Re: Bonding Rules 250.97, 2002 NEC #103171 05/11/02 08:17 PM
Joined: Apr 2002
Posts: 2,527
B
Bjarney Offline
Moderator
Some suggestions...Square-D makes NEMA-12 [NOT '12K' or ‘AWK’ suffix] XOP fusible disconnect switches without knockouts. Westinghouse/C-H makes NEMA-12 breaker enclosures of similar construction. Many 5½" depth panelboard cans are available with 'blank endwalls.' The 12’s are equal or somewhat less in price compared to 3R. ‘NOKO’ NEMA-1, -3 and -3R screw-cover gutters and pull cans are out there too.

KO reducing rings are {or should be} suicide.

Re: Bonding Rules 250.97, 2002 NEC #103172 05/11/02 11:13 PM
Joined: Nov 2000
Posts: 2,148
R
resqcapt19 Offline
Member
Redsy,
That is exactly what I was thiniking. Most code experts say that only one end of a service raceway requires bonding, so I would think that if the supply end was properly bonded, there would be no need to bond the load end, assuming that the EGC is used to bond the enclosure.
Don(resqcapt19)


Don(resqcapt19)

Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
CDS
CDS
Nicholson Ga
Posts: 34
Joined: June 2006
Show All Member Profiles 
Top Posters(30 Days)
Trumpy 8
NORCAL 3
Popular Topics(Views)
269,906 Are you busy
204,341 Re: Forum
192,561 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3